JP2000002120A - Control device for variable turbo-charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a variable turbo-charger which can prevent occurrence of disturbance caused by EGR control so as to carry out supercharge pressure F/B control which is always suitable. SOLUTION: A vane basic manipulated value SFF is compensated in accordance with a vane compensating coefficient Kegr which can be obtained from an EGR value Gr, and the vane opening is adjusted for restriction in accordance with thus compensated vane basic manipulated value SFF. As a result, the dynamic pressure of exhaust gas is increased so as to compensate the volume of exhaust gas for a decrease, thereby it is possible to prevent lowering of the boost pressure which is caused by the decrease in the exhaust gas volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine (hereinafter referred to as "internal combustion engine").
The present invention relates to a variable turbocharger control device capable of changing a variable blade (movable vane) according to an operating state of an engine.

[0002]

2. Description of the Related Art A variable turbocharger capable of changing a gas inflow rate to a turbine by a movable member can rapidly increase a supercharging pressure by appropriately controlling the movable member.
The torque can be improved in all regions from low speed to high speed, and in recent years, practical use has been advanced.

[0003] On the other hand, reduction of harmful components contained in exhaust gas has been increasingly demanded in recent years. In order to reduce NOx, one of harmful components, exhaust gas is directed to the intake passage side. An exhaust gas recirculation device (hereinafter, referred to as an EGR device) that recirculates at a predetermined ratio is implemented. As is well known, this EGR device uses the EGR based on the fuel injection amount Q and the engine rotational speed Ne according to, for example, a map shown in FIG.
The amount (the amount of exhaust gas recirculating to the intake passage) is obtained, and the opening of an EGR valve provided between the intake passage and the exhaust passage is controlled based on the EGR amount. The combustion temperature is reduced by the recirculated exhaust gas, and NOx
The occurrence of is suppressed.

By the way, in order to obtain a desired supercharging pressure by the variable turbocharger, the movable member must be adjusted to an appropriate opening in accordance with the exhaust gas energy determined by the operating state. However, when the exhaust gas is recirculated to the intake passage side by the EGR device, the exhaust gas energy decreases, and the opening degree of the movable member for obtaining a desired supercharging pressure changes. When the opening degree of the movable member changes, the back pressure (turbine upstream pressure) also changes, which also changes the differential pressure between the back pressure and the supercharging pressure and the amount of EGR recirculated by the EGR device.

Therefore, in general, in the region where the EGR device is operated, the EGR control amount of the EGR device and the movable member control amount of the variable turbocharger are stored in a map in advance, and the EGR device and the variable turbocharger are stored based on the map. And the charger. For example, JP-A-8-3
Japanese Patent No. 38256 discloses one example.

[0006]

However, as described above, when the EGR control amount and the movable member control amount are stored in the map in advance, for example, the EGR amount and the excess amount due to variations in the production of the EGR device and the variable turbocharger. Variations in charging pressure cannot be eliminated between individual engines, resulting in variations in emissions and performance.

In order to solve such a problem, feedback control (hereinafter referred to as F / B control) of the supercharging pressure and the EGR amount can be considered. However, the F / B control is applied to the EGR device and the variable turbocharger. When the control is applied, as described above, both act as disturbances on the respective systems, so that a problem occurs in the convergence.

An object of the present invention is to provide a control device for a variable turbocharger which suppresses disturbance to a supercharging pressure F / B control system by EGR control and realizes appropriate supercharging pressure F / B control. is there.

[0009]

In order to achieve the above object, according to the present invention, the control amount of the movable member control means is corrected by the control amount correction means based on the EGR amount, and the movable member control is performed in accordance with the corrected control amount. The movable member is controlled by the means. Therefore, even when the flow rate of the exhaust gas fluctuates due to the recirculation of the EGR to the intake passage side,
The movable member of the variable turbocharger is controlled accordingly, and the gas inflow speed into the turbine of the variable turbocharger is changed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a control device for a variable turbocharger for a diesel engine will be described below.

As shown in FIG. 1, an intake passage 3 is connected to an intake port 2 of the engine 1, and the intake air is guided into the intake port 2 and the intake passage 3 to be introduced into a combustion chamber 4 of each cylinder. You. The intake passage 3 is opened and closed by a compressor 6 of a variable turbocharger (hereinafter simply referred to as a turbocharger) 5 for supercharging the intake air, an intercooler 7 for cooling the intake air whose temperature has been raised by compression by the compressor 6, and a solenoid 8. An intake throttle valve 9 to be driven and a boost sensor 10 for detecting an intake pressure (hereinafter, referred to as a boost pressure) are provided. Further, an exhaust passage 13 is connected to the engine 1, and the exhaust gas which is ignited by compression in the combustion chamber 4 and burned is discharged to the outside through the exhaust passage 13. An exhaust pressure sensor 1 for detecting an exhaust pressure is provided in the exhaust passage 13.
4 and a turbine 15 of the turbocharger 5 which is coaxially coupled with the compressor 6 and is rotationally driven by exhaust gas.

In the turbine 15 of the turbocharger 5, a number of vanes 16 as movable members are arranged so as to surround the turbine rotor 15a.
6 is connected to the rod 18 of the vane adjustment actuator 17 (the connection state is not shown), and the opening is changed at the same time. As a result, the flow rate of the gas introduced into the turbine is adjusted.
The operation amount Lvane of the rod 18 is detected by a position sensor 19 attached to the vane adjustment actuator 17. In the vane adjustment actuator 17, the rod 18 is connected to a diaphragm 20, and is partitioned by the diaphragm 20 to form a negative pressure chamber 21. A compression spring 22 is provided in the negative pressure chamber 21, and the rod 18 is constantly urged to the projecting side by the compression spring 22.

The negative pressure chamber 2 of the vane adjusting actuator 17
A drive solenoid 24 is connected to 1 via a control pipe 23, and a vacuum pump 25 rotated by the engine 1 and a filter 26 communicating with the atmosphere are connected to the solenoid 24, respectively. In accordance with the excitation operation of the drive solenoid 24, the negative pressure of the vacuum pump 25 is stored in the negative pressure chamber 21 of the vane adjustment actuator 17.
Or, the atmospheric pressure through the filter 26 is selectively introduced,
When a negative pressure is introduced, the rod 18 is pressed against the bias of the compression spring 22.
Is operated to the retraction side, and when the atmospheric pressure is introduced, the compression spring 22
The rod 18 is operated to the protruding side by the urging, and the vane opening is adjusted accordingly as described above.

The intake passage 3 and the exhaust passage 13 are defined by a first EG
The first EGR passage 28
Is provided with a first EGR valve 29. Further, a portion of the first EGR passage 28 closer to the intake passage 3 than the first EGR valve 29 is connected to the exhaust passage 13 by a second EGR passage 30. EGR
A valve 31 and an EGR cooler 32 for cooling exhaust gas are provided. Although not described in detail, the first EGR valve 29
A driving solenoid is connected to the second EGR valve 31 similarly to the above-described vane adjustment actuator 17, and the EG is controlled in accordance with the excitation operation of the driving solenoid.
The R valves 29 and 31 are driven to adjust the degree of opening of the EGR passages 28 and 30. The valve lift amounts Legr1 and Legr2 of the EGR valves 29 and 31 are respectively determined by the position sensors 29 and 31.
a, 31a.

In the passenger compartment, an input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.) for storing control programs and control maps, etc., and a central processing unit (C)
An ECU 40 (engine control unit) including a PU, a timer counter, and the like is installed, and performs comprehensive control of the engine 1 including vane opening control of the turbocharger 5 and EGR control. On the input side of the ECU 40, detection information from the various sensors described above is input, and the ECU 4
0 is the vane opening or EGR based on these detection information.
The amount and the like are determined, and the vane adjustment actuator 17 and the EG
The driving of the solenoids 24 for driving the R valves 29 and 31 is controlled. The ECU 40 is connected to a large number of switches and sensors (not shown) on the input side, and is also connected to various warning lights, devices, and the like on the output side.

Next, a description will be given of a vane opening degree control process performed by the ECU 40 of the control device for the variable turbocharger configured as described above.

Here, the vane opening of the turbocharger 5 of the present embodiment is controlled in relation to the amount of EGR recirculated from the exhaust passage 13 to the intake passage 3. Therefore, first, EG
An outline of the R control will be described.

The EGR amount is obtained, for example, from the fuel injection amount Q and the engine rotation speed Ne in accordance with the map shown in FIG.
The opening degrees of 9, 31 are controlled. In the drawing, the EGR execution region is indicated by W / -EGR, and the EGR non-execution region is indicated by W / -EGR.
/ O-EGR.

In this embodiment, the EGR is cooled as required. Since the exhaust gas temperature is low in the engine cold state where the cooling water temperature is less than the predetermined value, the opening degree of the first EGR valve 29 is controlled while the second EGR valve 31 is kept fully closed,
The exhaust gas is recirculated without cooling through the first EGR passage 28. Further, in the engine warm-up state where the cooling water temperature is equal to or higher than a predetermined value, the opening degree of the second EGR valve 31 is controlled while the first EGR valve 29 is kept fully closed, and the second EGR valve 31 is controlled.
The high-temperature exhaust gas is cooled by the EGR cooler 32 via the GR passage 30 and then recirculated.

The above control is performed by the ECU 40 in accordance with an EGR control routine (not shown).
Reference numeral 40 resets the EGR execution determination flag Fegr when the EGR is not being performed, and sets the EGR execution determination flag Fegr when the EGR is being performed.

On the other hand, the ECU 40 executes a vane operation amount control routine shown in FIG. 3 at a predetermined control interval.
First, at step S2, the ECU 40 sets the vane basic operation amount SFF, that is, the operation amount of the rod 18 of the vane adjustment actuator 17, based on the fuel injection amount Q and the engine rotation speed Ne, as shown in FIG. Next, at step S4, it is determined whether or not the above-mentioned EGR execution determination flag Fegr has been set.
If R has not been executed (in FIG. 4, the switch has been switched to the W / O-EGR side), step S
In step 6, a boost pressure feedback process is executed.

More specifically, a target boost pressure is obtained from the fuel injection amount Q and the engine rotation speed Ne, and a feedback amount (a value of the rod 18) is calculated from the target boost pressure and the actual boost pressure Pb detected by the boost sensor 10. Then, the vane basic operation amount SFF is corrected based on the feedback amount to obtain the vane operation amount SFB. Next, in step S8, the driving solenoid 2 is controlled based on the vane operation amount SFB with reference to the current rod operation amount Lvane detected by the position sensor 19.
4 is driven and the vane adjustment actuator 17 adjusts the vane opening. In the present embodiment, the ECU 40 at the time of executing the processes of steps S2, S6, and S8 functions as a movable member control unit.

If the determination in step S4 is YES (Yes) and EGR is being executed (in FIG. 4, the switch has been switched to the W / -EGR side), the ECU 40 proceeds to step S10 to execute the vane operation. The correction amount Kegr is calculated. During the execution of the EGR, the exhaust gas introduced into the turbine 15 decreases by a considerable amount of the EGR amount. However, the vane correction amount Kegr is adjusted by adjusting the vane 16 to the throttle side for the purpose of compensating the decrease in the exhaust gas. Correction amount for increasing the dynamic pressure of the exhaust gas. This vane correction amount Kegr
Is obtained from the EGR amount Gr according to a preset map.

The EGR amount Gr is calculated according to the following equation.

Gr = A × Ko × Ket × Nef × KPLoss Here, A is an equivalent opening area constant representing a substantial communication area between the exhaust passage 13 side and the intake passage 3 side, and Ko is EG
An orifice coefficient Ket set based on the differential pressure before and after the R valve (the pressure difference between the exhaust passage 13 and the intake passage 3) DEP
Is an EGR temperature correction coefficient for correction based on the EGR temperature, Nef is an engine rotation cycle representing time required for 1/2 rotation of the engine 1, and KPLoss is a pressure loss correction for correcting a pressure loss of the EGR cooler 32. It is a coefficient. Hereinafter, the setting procedure of each item will be described. The equivalent opening area constant A is the valve lift amount Legr1, Legr1, of the EGR valve on the side currently controlled for the opening degree, that is, the first EGR valve 29 when the engine is cold, and the second EGR valve 31 when the engine is warm. From Legr2,
It is determined according to a preset map.

The orifice coefficient Ko is calculated from the differential pressure DEP before and after the EGR valve according to the following equation.
Is determined according to a preset map.

DEP = Pex-Pbavr Pex is the exhaust pressure detected by the exhaust pressure sensor 14, and Pbavr is the average value of the boost pressure Pb detected by the boost sensor 10.

The EGR temperature correction coefficient Ket is determined by a predetermined EGR
Based on the temperature, a calculation is made from the engine rotation speed Ne and the fuel injection amount Q according to a preset map. The engine rotation period Nef is equal to the engine rotation speed N.
Calculate from e.

The cooler pressure loss correction coefficient KPLoss is the value of EGR due to the passage of the EGR cooler 32 when the engine is cold.
Is set to 1.0 because no pressure loss occurs, and a pressure loss occurs in a warm-up state, so that a predetermined value (KPLoss <
1.0).

In step S10, a vane correction amount Kegr is finally calculated from the EGR amount Gr thus obtained. Next, the ECU 40 corrects the vane basic operation amount SFF to the throttle side using the vane correction amount Kegr in step S12, and thereafter executes boost pressure feedback processing in the same manner as described above in step S6, and executes vane operation processing in step S8. Then, this routine ends. Here, in the present embodiment, the ECU 40 at the time of executing the processing of step S12 functions as a control amount correction unit.

As described above, when the exhaust gas is recirculated to the intake passage side by executing the EGR control, the vane opening of the turbocharger 5 is reduced in accordance with the EGR amount Gr by the processes of steps S10 and S12. Adjusted to the side. As a result, the dynamic pressure of the exhaust gas increases to compensate for the decrease in the exhaust gas, thereby preventing a decrease in the boost pressure caused by the decrease in the exhaust gas. Therefore, disturbance to the supercharging pressure F / B system due to EGR is minimized, and the air amount can be secured even during the introduction of EGR.
It is possible to increase both the intake air and the EGR.

Although the description of the embodiments has been completed, the embodiments of the present invention are not limited to these embodiments. For example,
In the above embodiment, the control device of the variable turbocharger for a diesel engine is embodied. However, the present invention is applicable as long as the variable turbocharger is combined with an EGR device. The gasoline engine can be changed, and the type of the turbocharger 5 can be changed to the twin scroll type or the like instead of the vane type of the present embodiment.

In the above-described embodiment, the EGR amount Gr recirculated to the intake passage 3 is calculated in step S10 based on the valve lift amounts Legr1, Legr2 of the EGR valves 29, 31 and the front-rear differential pressure DEP. Estimated. This is engine 1
For example, a means for directly measuring the EGR amount Gr is provided in the EGR passage, and the vane opening is adjusted based on the measurement result. You may. The EGR amount determination means of the present invention includes such a case.

[0034]

As described above, according to the variable turbocharger control apparatus of the present invention, since the movable member of the variable turbocharger is controlled in accordance with the EGR amount, the exhaust gas is recirculated to the intake passage side of the exhaust gas. Even when the flow rate of the fuel oil is fluctuating, the fluctuation of the boost pressure can be prevented beforehand, so that the boost pressure F / B control can always be appropriately executed regardless of the EGR control.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a control device of a variable turbocharger of an embodiment.

FIG. 2 is an explanatory diagram showing a map for setting an EGR amount.

FIG. 3 is a flowchart illustrating a vane operation amount control routine executed by an ECU.

FIG. 4 is a block diagram showing a procedure for setting a vane operation amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine (internal combustion engine) 3 Intake passage 5 Turbocharger 13 Exhaust passage 16 Vane (movable member) 40 ECU (movable member control means, control amount correction means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 25/07 570 F02B 37/12 301Q F-term (Reference) 3G005 DA02 EA04 EA15 EA16 FA06 GA04 GB24 GC05 GC07 GE01 GE08 GE09 HA12 HA13 JA05 JA24 JA28 JA39 JA42 JB20 3G062 AA01 AA05 BA04 EA10 ED08 FA06 FA09 FA10 FA11 FA12 FA13 FA24 GA01 GA06 GA14 GA21 GA22 3G084 AA01 BA07 BA13 BA20 DA04 EB08 EB12 EB16 EC03 FA07 FA12 A09 ABA3A03 ABA3A02 DC10 DE06S DG06 DG09 EA02 EA17 EA29 EC03 EC10 FA06 HA01Z HA16X HB01Z HD07X HD08Z HE01Z

Claims (1)

[Claims] A variable turbocharger, which is driven to rotate by exhaust gas flowing through an exhaust passage of an internal combustion engine to supercharge intake air in an intake passage and change a gas inflow speed to a turbine by a movable member. A movable member control means for controlling the movable member in accordance with an operation state of the internal combustion engine; and a control amount of the movable member control means corrected based on an EGR amount recirculated from the exhaust passage side to the intake passage side. A control device for a variable turbocharger, comprising: