JP2005113825A - Control device and control method of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a large amount of EGR, to control not to largely increase the number of revolutions of a turbocharger, and thereby to secure durability reliability of the turbocharger. <P>SOLUTION: An engine 1 has the turbocharger 3 with variable guide vanes, and an EGR system 5, V. The engine 1 further has: detecting means 8, 9, 11 detecting control parameters determining an operational status of the engine 1; a control means 10; an EGR valve V recirculating exhaust gas in an intake system; and a variable vane angle adjusting means 35 adjusting the angle of the variable guide vanes. When a rate of closing of the EGR valve V is a predetermined value or more, and the control parameters (engine load, engine speed, the number of revolutions of a turbine) detected by the detecting means 8, 9, 11 are not less than a predetermined value, the control means 10 outputs a control signal to the variable vane angle adjusting means 35 to make the variable guide vanes open at a predetermined angle, and controls the EGR valve V to close after the variable guide vanes are opened at the predetermined angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to an operation control apparatus for an engine having a variable capacity turbocharger and an EGR system, and a control method therefor, and more particularly, to reduce NOx contained in exhaust gas in an automobile engine. The present invention relates to an operation control device for increasing an EGR amount when a turbocharger and an EGR system are combined, and a control method therefor.

In order to increase the amount of EGR, there is a method of increasing the pressure in the exhaust manifold by increasing the opening of the EGR valve and closing the variable blades of the variable displacement turbocharger.
From that state, for example, when the accelerator is depressed during acceleration and the amount of EGR is suddenly reduced, if the EGR valve is simply closed, the combustion gas that has been flowing to the intake side suddenly flows into the turbocharger, The rotation speed of the turbocharger increases rapidly and significantly. If the rotational speed of the turbocharger exceeds the limit, the impeller of the turbocharger may be damaged by the centrifugal force of rotation, or durability reliability may be greatly impaired.

  Here, there has been proposed an EGR device for an engine with a turbocharger that can perform an optimum amount of exhaust gas recirculation, so-called “EGR”, in various engine operating states (see, for example, Patent Document 1).

However, the above proposal requires a waste pipe that communicates between the turbine outlet side and the exhaust manifold, and an exhaust waist valve that is interposed in the waste pipe. This complicates the system configuration and control, which in turn increases costs. Will be invited.
JP 2002-106479 A

  The present invention has been proposed in view of the above-described problems of the prior art. A large amount of EGR can be secured, and when the EGR is reduced, control is performed so that the rotational speed of the turbocharger does not increase significantly. An object of the present invention is to provide an engine control device and a control method thereof that can ensure the durability and reliability of the turbocharger.

  The engine control apparatus of the present invention determines the operating state of the engine (1) in an engine having a variable displacement turbocharger (3) having a variable guide vane (34) and an EGR system (5, V). Detection means (8, 9, 11, Stn) for detecting control parameters, control means (10), an EGR valve (V) interposed in a reflux pipe (5) for recirculating exhaust gas to the intake system, Variable blade angle adjusting means (35) for adjusting the angle of the variable guide blade (34) of the variable displacement turbocharger (3), and the control means (10) is a closing rate of the EGR valve (V). When the control parameter (engine load, engine speed, turbine speed, etc.) detected by the detection means (8, 9, 11, Stn) is greater than a predetermined value. Angle adjustment A control signal is output to the stage (35) so as to open at a predetermined opening, and the EGR valve (V) is controlled to close after the variable blade (34) is opened at a predetermined opening. (Claim 1; FIGS. 1, 3, 5, and 7).

  The means for detecting the control parameter is an engine load sensor (8) for detecting engine load and / or an engine rotation sensor (9) for detecting engine rotation (Claim 2; FIG. 1).

  The means for detecting the control parameter is a speed sensor (Stn) for measuring the rotational speed of the turbine impeller (33) of the capacity variable turbocharger (Claim 3; FIG. 3).

  The engine control device of the present invention includes a timer (12), and closes the EGR valve (V) after a predetermined time has elapsed after outputting the control signal so that the variable blade (34) opens at a predetermined opening. (Claim 4; FIG. 5).

  The variable blade angle adjusting means (35) incorporates an angle detecting means (36), and the control means (10D) is configured to make the variable blade (34) up to a predetermined angle based on information from the angle detecting means (36). The predetermined angle is maintained at the time of opening, and then the EGR valve (V) is controlled to be closed (Claim 5; FIG. 7).

  According to the engine control method of the present invention, an EGR valve (V) is predetermined in an engine (1) having a variable displacement turbocharger (3) having a variable guide vane (34) and an EGR system (5, V). A step (S3) of determining whether or not the closing rate of the engine is equal to or greater than a predetermined closing rate, and a control parameter (engine) for determining an operating state of the engine as a result detected by the detecting means when the EGR valve (V) is equal to or higher than a predetermined closing rate (S4) for determining whether or not the load, the engine speed, the turbine speed, etc. are equal to or higher than a predetermined value, and variable when the control parameters (engine load, engine speed, turbine speed, etc.) are higher than the predetermined value After opening the variable blade (34) to a predetermined angle by the blade angle adjusting means (35) (S6, S16, S26, S36) and after opening the variable blade (34) to a predetermined angle GR valve (V) closing step (S7, S17, S29, S39) is characterized by having a (Claim 6; Fig. 2, 4, 6, 8).

  In the step (S4) of determining whether or not the control parameter is an engine load and / or an engine speed and the control parameter is greater than or equal to a predetermined value, it is determined whether or not the engine load is greater than or equal to a predetermined value. And / or it is judged whether an engine speed is more than predetermined value (Claim 7; FIG. 2).

  The control parameter is the rotational speed of the turbine of the variable capacity turbocharger. In the step (S14) of determining whether or not the control parameter is greater than or equal to a predetermined value, the rotational speed of the turbine of the variable capacity turbocharger is greater than or equal to the predetermined value. (Claim 8; FIG. 4).

  The engine control method of the present invention includes a step (S28) of determining whether or not the time has continued for a predetermined time after the step (S26) of opening the variable blade (34) to a predetermined angle. Control is performed so that the EGR valve is closed (S29) after a lapse of time (Claim 9; FIG. 6).

  The engine control method of the present invention includes a step (S37) of measuring the actual opening of the variable blade (34) after the step (S36) of opening the variable blade (34) to a predetermined angle, A step (S38) for determining whether or not the variable blade has been opened to a predetermined opening, and when the variable blade is opened to the predetermined opening, the opening is maintained and the EGR valve (V) is closed (S39). (Claim 10; FIG. 8).

  The present invention is preferably applied to an engine equipped with a variable displacement turbocharger with an intercooler in order to cope with a decrease in output due to EGR.

  According to the engine control device and the control method of the present invention having the above-described configuration and method, the engine load and the engine speed are constantly monitored. In order to obtain the opening degree of the variable blade (34) of the turbocharger (3) that matches the engine load and the engine speed before, the turbocharger (3) can be operated without excessive load acting on the turbocharger (3). Durability and reliability can be secured.

  In addition, the rotational speed of the variable capacity turbocharger (3) is constantly monitored. For example, even if the EGR amount is suddenly reduced depending on the operating conditions, the variable speed can be matched to the rotational speed of the turbocharger (3) before that. Since the opening of the blade (34) is set, the durability of the turbocharger can be ensured without excessive load acting on the turbocharger.

  In addition, even if the EGR amount is suddenly reduced depending on the operating condition, a control signal is output so that the opening of the variable blade (34) corresponding to the engine load and the engine speed is output, and then the EGR valve is continued for a predetermined time. Since (V) is closed, the durability of the turbocharger (3) can be ensured without an excessive load acting on the turbocharger (3).

  Furthermore, according to the control device and method for an engine of the present invention having the above-described configuration and control method, for example, even if the EGR amount is drastically reduced depending on the operating condition, the nozzle vane variable blades corresponding to the engine load and the engine speed Since the EGR valve is closed after the opening degree of (34) is monitored and confirmed, the durability reliability of the turbocharger (3) can be ensured without applying an excessive load to the turbocharger (3).

  The best mode for carrying out the present invention will be described with reference to the accompanying drawings.

First, the configuration of an engine control device including the engine of the first embodiment will be described with reference to FIG.
A variable capacity turbocharger 3 is attached to the exhaust manifold 2 side of the engine 1.

  The variable capacity turbocharger 3 includes a turbine 31 in which a turbine impeller rotates by exhaust, and a compressor 32 that is rotated by the rotation of the turbine 31 and compresses intake air by the rotation.

  As shown in the partial detail view of FIG. 9, the turbine 31 continuously changes the flow passage cross-sectional area of the exhaust gas to the turbine blade 33 a at the outer peripheral portion of the turbine impeller 33 constituted by the plurality of turbine blades 33 a. A plurality of nozzle vanes (guide vanes) 34 that can be configured to surround the turbine impeller 33.

The plurality of nozzle vanes 34 are not drawn clearly in the drawing, but their opening degrees are steplessly changed by an actuator (reference numeral 35 in FIG. 1).
In other words, the opening degree of the nozzle vane 34 can be freely adjusted by controlling the actuator 35, and thus the rotational speed of the turbine impeller 33 is controlled.
In FIG. 9, the nozzle vane 34 indicated by a solid line indicates a state with a large opening, and the nozzle vane 34 indicated by a broken line indicates a state with a small opening.

  Returning to FIG. 1, the vicinity of the turbocharger connection portion of the exhaust manifold 2 and the vicinity of the inlet 41 of the intake manifold 4 are communicated with each other by a reflux pipe (EGR pipe) 5 that recirculates exhaust gas to the intake side.

  The EGR pipe 5 is provided with an EGR valve V for adjusting the exhaust gas flow rate.

  The compressor 32 and the intake manifold 4 of the turbocharger 3 are communicated with each other by an intake pipe 7 having an intercooler 6 for cooling intake air.

  The engine 1 is provided with a load sensor 8 for detecting the engine load and an engine rotation sensor 9 for detecting the engine speed, and is connected to the control unit 10 by a signal line Li. The control unit 10 is also connected to the accelerator opening sensor 11 by a signal line Li.

  The actuator 35 and the EGR valve V are connected to the control unit 10 by a control signal line Lo.

The control unit 10 constantly detects the opening degree of the EGR valve V, the closing rate of the EGR valve V exceeds a set ratio (N ₁ %), the engine load is equal to or greater than a predetermined value (N ₂ ), and the engine When the rotational speed is equal to or greater than a predetermined value (N ₃ ), a control signal is transmitted to the actuator 35 so as to open the opening of the nozzle vane 34 of the variable displacement turbocharger 3 to a predetermined opening. After the opening degree is opened to a predetermined opening degree (n%), a control signal is transmitted to the EGR valve V so as to close the valve.

  Next, the control method of the first embodiment will be described with reference to FIG.

  First, the control unit 10 monitors until the accelerator is depressed by the information from the accelerator opening sensor 11 (step S1 loop). If the accelerator is depressed (YES in step S1), the process proceeds to the next step S2. move on.

  In step S2, the control unit 10 monitors until the EGR valve V needs to be moved in the closing direction (step S2 → step S1 → step S2 loop).

If it is necessary to move the EGR valve V in the closing direction (YES in step S2), it is determined whether or not the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (step S3).
If the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (YES in Step S3), the process proceeds to Step S4, while if the closing rate is less than N ₁ % (NO in Step S3), After the EGR valve V is immediately closed (step S5), the process returns to step S1, and step S1 and subsequent steps are repeated again.

In step S4, the control unit 10 determines whether or not the engine load is equal to or greater than a predetermined value (N ₂ %) and the engine speed is equal to or greater than a predetermined value N _{3 based on} information from the engine load sensor 8 and the engine rotation sensor 9. to decide.
If the engine load is equal to or greater than the predetermined value (N ₂ %) and the engine speed is equal to or greater than the predetermined value N ₃ (YES in step S4), the process proceeds to step S6.
On the other hand, if the engine load is less than the predetermined value (N ₂ %) and the engine speed is less than the predetermined value N ₃ (NO in step S4), either the engine load or the engine speed is a predetermined value. If it is less (NO in step S4), the process returns to step S1 via step S5.

  In step S6, a control signal is transmitted to the actuator 35 of the variable displacement turbocharger 3 so that the opening degree of the nozzle vane 34 is opened to a predetermined opening degree (n%), and the EGR valve is opened after the nozzle vane 34 is opened to the predetermined opening degree. After transmitting a control signal to the EGR valve V so as to close V (step S7), the process returns to step S1 again, and step S1 and subsequent steps are repeated.

  According to the first embodiment of the configuration and the control method, the engine load and the engine speed are constantly monitored. For example, even if the EGR amount is suddenly decreased depending on the operation state, the engine load and the engine speed are set in advance. Since the opening of the nozzle vane 34 of the turbocharger 3 is matched, the durability of the turbocharger 3 can be ensured without an excessive load acting on the turbocharger 3.

Next, a second embodiment will be described with reference to FIGS. In the first embodiment of FIGS. 1 and 2, the parameters for knowing the operating state of the engine are the engine load and the engine speed, and the means for detecting them are the engine load sensor and the engine speed sensor.
On the other hand, in the second embodiment shown in FIGS. 2 and 4, the parameter for knowing the operating state of the engine is the rotation speed of the turbocharger 3, and the means for detecting them is a rotation sensor for detecting the rotation speed of the turbocharger 3. Stn.
Except that the parameters for knowing the operating condition of the engine and the detection means are changed, the configuration is substantially the same as that of the first embodiment shown in FIGS.
In addition, the code | symbol 10B is attached | subjected with respect to the control unit in 2nd Embodiment.

With reference to FIG. 4, the control method of 2nd Embodiment is demonstrated.
First, the control unit 10B monitors until the accelerator is depressed based on information from the accelerator opening sensor 11 (a loop in step S11). If the accelerator is depressed (YES in step S1), the process proceeds to the next step S12. move on.

  In step S12, the control unit 10B monitors until the EGR valve V needs to be moved in the closing direction (step S12 → step S11 → step S12 loop).

If it is necessary to move the EGR valve V in the closing direction (YES in step S12), it is determined whether or not the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (step S13).
If the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (YES in step S13), the process proceeds to step S14, whereas if the closing rate is less than N ₁ % (NO in step S13), After the EGR valve V is immediately closed (step S15), the steps after step S11 are repeated again.

In step S14, the control unit 10B determines whether the rotational speed of the turbocharger 3 is equal to or greater than a predetermined value (N ₄ %) based on information from the rotation sensor Stn.
If the rotation speed of the turbocharger 3 is equal to or greater than a predetermined value (N ₄ %) (YES in step S14), the process proceeds to step S16.
On the other hand, when the rotation speed of the turbocharger 3 is less than the predetermined value (N ₄ %) (NO in Step S14), the process proceeds to Step S15, returns to Step S11 again, and repeats Step S11 and subsequent steps.

  In step S16, a control signal is transmitted to the actuator 35 of the variable displacement turbocharger 3 so that the opening degree of the nozzle vane 34 is opened to a predetermined opening degree (n%), and the EGR valve is opened after the nozzle vane 34 is opened to the predetermined opening degree. After transmitting a control signal to the EGR valve V so as to close V (step S17), the process returns to step S11 again, and steps S11 and after are repeated.

  According to the second embodiment of the configuration and the control method, the rotational speed of the variable capacity type turbocharger 3 is constantly monitored. For example, even if the EGR amount is suddenly reduced depending on the operation state, the turbocharger 3 In order to set the opening degree of the nozzle vane 34 corresponding to the rotational speed of the turbocharger 3, it is possible to ensure the durability reliability of the turbocharger 3 without an excessive load acting on the turbocharger 3.

Next, a third embodiment will be described with reference to FIGS. The third embodiment of FIGS. 5 and 6 differs from the first embodiment of FIGS. 1 and 2 only in that the timer 12 is incorporated in the control unit 10C, and the other configuration is substantially the same as the first embodiment. Since it is the same as that of embodiment, the subsequent description regarding the structure of an apparatus is abbreviate | omitted.
Regarding control, a control signal is transmitted to the first embodiment so that the nozzle vane 34 opens to a predetermined opening (n%), and the state is maintained for a predetermined time, and then the EGR valve is closed. Different points.

With reference to FIG. 6, the control method of 3rd Embodiment is demonstrated.
First, the control unit 10C monitors until the accelerator is depressed by the information from the accelerator opening sensor 11 (step S21 loop). If the accelerator is depressed (YES in step S21), the process proceeds to the next step S22. move on.

  In step S22, the control unit 10C monitors until the EGR valve V needs to be moved in the closing direction (step S22 → step S21 → step S22 loop).

If it is necessary to move the EGR valve V in the closing direction (YES in step S22), it is determined whether or not the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (step S23).
If the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (YES in step S23), the process proceeds to step S24, while if the closing rate is less than N ₁ % (NO in step S23). After the EGR valve V is immediately closed (step S25), the process returns to step S21, and step S21 and subsequent steps are repeated again.

In step S24, the control unit 10C determines that the engine load is equal to or greater than a predetermined value (N ₂ %) and the engine speed is equal to or greater than the predetermined value N ₃ (step S5) based on information from the engine load sensor 8 and the engine rotation sensor 9. Determine whether or not.
If the engine load is equal to or greater than the predetermined value (N ₂ %) and the engine speed is equal to or greater than the predetermined value N ₃ (YES in step S4), the process proceeds to step S26.
On the other hand, if the engine load is less than the predetermined value (N ₂ %) and the engine speed is less than the predetermined value N ₃ (NO in step S24), or either the engine load or the engine speed is a predetermined value. If it is less (NO in step S24), the process proceeds to step S25, returns to step S21, and repeats step S21 and subsequent steps.

  In step S26, a control signal is transmitted to the actuator 35 of the variable capacity turbocharger 3 so that the opening degree of the nozzle vane 34 is opened to a predetermined opening degree (n%), and measurement with a timer is started in this state (step S27). ).

  In the next step S28, the control unit 10C checks until a predetermined time elapses while a signal for opening the nozzle vane 34 to a predetermined opening (n%) is transmitted (step S28 → step). If it has elapsed (YES in step S28), after closing the EGR valve V (step S29), the process returns to step 21 and repeats step S1 and subsequent steps again.

  According to the third embodiment of the configuration and the control method, for example, even if the EGR amount is suddenly decreased depending on the operating condition, after transmitting a signal to open the opening of the nozzle vane 34 corresponding to the engine load and the engine speed, Since the EGR valve is closed after a predetermined time has elapsed, an excessive load does not act on the turbocharger 3, and the durability reliability of the turbocharger 3 can be ensured.

  Next, a fourth embodiment will be described with reference to FIGS. In the fourth embodiment shown in FIGS. 7 and 8, the actual opening of the nozzle vane 34 is always fed back to the control unit, compared to the first embodiment of FIGS. 1 and 2, and the actual opening of the nozzle vane is After opening to a predetermined opening degree, it is different in that the actual opening degree of the nozzle vane is stopped from being opened further and the EGR valve is closed. In terms of configuration, the only difference is that the actual opening degree of the nozzle vane is detected by the angle detection means 36 incorporated in the actuator 35 and is always fed back to the control unit side. The control unit is denoted by reference numeral 10D.

With reference to FIG. 8, the control method of 4th Embodiment is demonstrated.
First, the control unit 10D monitors until the accelerator is depressed based on information from the accelerator opening sensor 11 (a loop in step S31). If the accelerator is depressed (YES in step S31), the process proceeds to the next step S32. move on.

  In step S32, the control unit 10D monitors until the EGR valve V needs to be moved in the closing direction (step S32 → step S31 → step S32 loop).

If it is necessary to move the EGR valve V in the closing direction (YES in step S32), it is determined whether or not the closing rate of the EGR valve V is N ₁ % (for example, 50%) or more (step S33).
If the closing rate of the EGR valve V is N ₁ % (eg, 50%) or more (YES in step S33), the process proceeds to step S34, and if the closing rate is less than N ₁ % (NO in step S23), the EGR valve After V is immediately closed (step S35), steps S21 and after are repeated again.

In step S34, the control unit 10D determines that the engine load is equal to or greater than a predetermined value (N ₂ %) and the engine speed is equal to or greater than the predetermined value N ₃ (step S5) based on information from the engine load sensor 8 and the engine rotation sensor 9. Determine whether or not.
If the engine load is equal to or greater than the predetermined value (N ₂ %) and the engine speed is equal to or greater than the predetermined value N ₃ (YES in step S34), the process proceeds to step S36.
On the other hand, if the engine load is less than the predetermined value (N ₂ %) and the engine speed is less than the predetermined value N ₃ (NO in step S34), either the engine load or the engine speed is a predetermined value. If it is less (NO in step S34), the process proceeds to step S35, returns to step S31, and repeats step S31 and subsequent steps.

  In step S36, a control signal is transmitted to the actuator 35 of the variable displacement turbocharger 3 so that the opening degree of the nozzle vane 34 is opened to a predetermined opening degree (n%), and the actual opening degree of the nozzle vane 34 is further set by the angle detection means 36. Measurement is performed (step S37).

  In the next step S38, the control unit 10D determines whether or not the opening degree of the nozzle vane 34 has been opened to a predetermined opening degree (n%) based on the information from the angle detection means 36. If it is opened at (n%) (YES in step S38), the nozzle vane 34 is stopped from being opened any more, the EGR valve V is closed (step S39), the process returns to step S31, and the steps from step S31 are repeated again. . On the other hand, if it is not opened to a predetermined opening degree (n%) (NO in step S38), the process returns to step S36 and repeats step S36 and subsequent steps.

  According to the fourth embodiment of the configuration and the control method, for example, even if the EGR amount is suddenly reduced depending on the operating condition, it is monitored and confirmed until the nozzle vane opening matches the engine load and the engine speed. Then, since the EGR valve is closed after that, an excessive load is not applied to the turbocharger, and the durability reliability of the turbocharger can be ensured.

The block diagram which shows the whole structure of 1st Embodiment of this invention. The flowchart which showed the control method in 1st Embodiment of this invention. The block diagram which shows the whole structure of 2nd Embodiment of this invention. The flowchart which showed the control method in 2nd Embodiment of this invention. The block diagram which shows the whole structure of 3rd Embodiment of this invention. The flowchart which showed the control method in 1st Embodiment of this invention. The block diagram which shows the whole structure of 4th Embodiment of this invention. The flowchart which showed the control method in 1st Embodiment of this invention. The fragmentary sectional view which shows the action | operation of the nozzle vane of a capacity | capacitance variable turbocharger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust manifold 3 ... Variable displacement turbocharger 4 ... Intake manifold 5 ... Reflux pipe 6 ... Intercooler 7 ... Intake pipe 8 ... Load sensor 9 ... Engine rotation sensors 10, 10B, 10C, 10D ... Control unit 31 ... Turbine 32 ... Compressor 34 ... Nozzle vane 35 ... Actuator 36 ... Angle detection means

Claims (10)

  In an engine having a variable displacement turbocharger having a variable guide vane and an EGR system, a detecting means for detecting a control parameter for determining the operating state of the engine, a control means, and a reflux pipe for recirculating exhaust gas to an intake system And an EGR valve interposed in the variable displacement angle adjusting means for adjusting the angle of the variable guide vane of the variable displacement turbocharger, wherein the control means has a closing rate of the EGR valve equal to or greater than a predetermined value. When the control parameter detected by the detecting means is equal to or greater than a predetermined value, a control signal is output to the variable blade angle adjusting means so as to open at a predetermined opening, and the variable blade is opened at a predetermined opening. A control apparatus for an engine, characterized in that the EGR valve is controlled to be closed after a while.   2. The engine control device according to claim 1, wherein the means for detecting the control parameter is an engine load sensor for detecting an engine load and / or an engine rotation sensor for detecting engine rotation.   2. The engine control apparatus according to claim 1, wherein the means for detecting the control parameter is a speed sensor for measuring a rotational speed of a turbine impeller of the variable capacity turbocharger.   A timer is provided, and is configured to control the EGR valve to close after a predetermined time has elapsed since outputting a control signal so that the variable blades are opened at a predetermined opening degree. The engine control device according to claim 3.   The variable blade angle adjusting means incorporates an angle detection means, and the control means maintains a predetermined angle when the variable blade opens to a predetermined angle based on information from the angle detection means, and then the EGR valve 4. The engine control device according to claim 1, wherein the engine control device is configured to be controlled to be closed.   In an engine having a variable displacement turbocharger having a variable guide vane and an EGR system, a step of determining whether or not the EGR valve is equal to or higher than a predetermined closing rate, and a detecting means when the EGR valve is equal to or higher than a predetermined closing rate Determining whether or not the control parameter for determining the engine operating state, which is the result detected by the above, is greater than or equal to a predetermined value, and when the control parameter is greater than or equal to the predetermined value, the variable blade angle adjusting means causes the variable blade to move to a predetermined angle. And a step of closing the EGR valve after opening the variable blade to a predetermined angle.   In the step of determining whether the control parameter is an engine load and / or an engine speed and the control parameter is equal to or greater than a predetermined value, it is determined whether the engine load is equal to or greater than a predetermined value and / or The engine control method according to claim 6, wherein it is determined whether or not the engine speed is a predetermined value or more.   The control parameter is the rotational speed of the turbine of the variable capacity turbocharger. In the step of determining whether the control parameter is equal to or higher than a predetermined value, whether the rotational speed of the turbine of the variable capacity turbocharger is higher than the predetermined value. The engine control method according to claim 6, wherein it is determined whether or not.   7. The method according to claim 6, further comprising the step of determining whether or not a time has continued for a predetermined time after the step of opening the variable blade to a predetermined angle, and controlling the EGR valve to be closed after the time has continued for a predetermined time. 7. The engine control method according to any one of claims 7 and 8.   After the step of opening the variable blade to a predetermined angle, the step of measuring the actual opening of the variable blade, and the step of determining whether or not the variable blade has been opened to a predetermined opening, The engine control method according to any one of claims 6, 7, and 8, wherein control is performed so that the predetermined opening degree is maintained when the valve is opened and the EGR valve is closed.

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