JP2017180196A - Control device of multi-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of uniformly distributing an EGR gas to cylinders of a multi-cylinder engine by mixing EGR and fresh air, in particular, in a case when EGR concentration is high, without increasing a size of the engine.SOLUTION: A control device of a mult-cylinder engine includes a throttle valve 11 disposed in an intake system 10 of the multi-cylinder engine 20 and adjusting an introduction amount of fresh air to a downstream side, an EGR introduction port formed between the multi-cylinder engine 20 and the throttle valve 11, and an opening control device for controlling a maximum opening of the throttle valve 11. The opening control device reduces and corrects the maximum opening of the throttle valve 11 in comparison with a case when an EGR rate is smaller than a prescribed value, when an exhaust gas is circulated to the intake system 10 from the EGR introduction port, and the EGR rate is the prescribed value or more.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for a multi-cylinder engine, and more particularly to a control device for a multi-cylinder engine that recirculates exhaust gas through an EGR passage.

  Conventionally, by circulating exhaust gas discharged from a multi-cylinder engine to the intake side of the multi-cylinder engine, nitrogen oxide (NOx) contained in the exhaust gas can be reduced and fuel consumption can be improved. An EGR (Exhaust Gas Recirculation) control technique is known. In the so-called external EGR in which EGR gas discharged from a multi-cylinder engine is circulated through an EGR passage that connects an exhaust passage of the engine and an intake passage to the engine in EGR control, the EGR passage is connected to the multi-cylinder. The engine is connected between a throttle valve on the upstream side of the engine and an intake manifold for distributing cylinders to each cylinder of the multi-cylinder engine. The EGR gas from the exhaust passage is introduced into the intake passage from the connection between the EGR passage and the intake passage, and is mixed with the fresh air flowing from the upstream side of the intake passage until reaching the intake manifold. , And distributed to each cylinder via the intake manifold.

  Normally, when the EGR gas is circulated in the intake passage, the total amount of EGR gas introduced into the intake passage can be managed, but in a multi-cylinder engine, how much EGR gas is supplied to each cylinder is monitored. That is not done. The fresh air supply amount to the multi-cylinder engine and the fuel supply amount to each cylinder are controlled on the premise that the EGR gas that has passed through the EGR passage is uniformly distributed to each cylinder. The amount of EGR gas actually supplied to each cylinder is required to be uniform for each cylinder. In this case, if the EGR concentration or EGR amount of the gas to be recirculated is small, the efficiency of the engine does not decrease even if the amount of EGR gas supplied to each cylinder is not uniform, but the recirculated EGR gas When the amount of EGR gas supplied to each cylinder is uneven, the combustion efficiency varies from cylinder to cylinder, and the required engine output cannot be secured. was there.

  In order to solve such a problem, when supplying EGR gas to a multi-cylinder engine, a technique for reducing the difference in EGR amount for each cylinder and supplying EGR gas uniformly to each cylinder is known (for example, Patent Document 1).

JP 2013-245572 A

  In Patent Document 1, an EGR mixing chamber is provided between the throttle valve and the engine, turbulence is generated in the mixing chamber, EGR and fresh air are mixed, and the amount of EGR supplied to each cylinder is made uniform. Like to do.

  However, the technique of Patent Document 1 has a problem that it is not preferable because the engine is enlarged. That is, the space between the throttle valve and the engine is very limited, and it is difficult to design a mixing chamber for EGR in such a very limited space. Even if it is provided, the engine will be enlarged.

  Therefore, the present invention has been made to solve the above-described problems, and without increasing the size of the engine, particularly when the EGR concentration is high, EGR and fresh air are mixed, and the multi-cylinder engine It is an object of the present invention to provide a control device that can uniformly distribute EGR gas to each cylinder.

  In order to solve the above-described problems, the present invention is a control device for a multi-cylinder engine, and is provided in an intake system of the multi-cylinder engine, and is a throttle valve for adjusting the amount of fresh air introduced downstream. And an EGR introduction port provided between the multi-cylinder engine and the throttle valve, and an opening degree control device for controlling the opening degree of the throttle valve, the opening degree control device comprising an EGR introduction port When the exhaust gas is recirculated to the intake system and the EGR rate is greater than or equal to a predetermined value, the maximum opening of the throttle valve is corrected to be closed compared to when the EGR rate is smaller than the predetermined value.

  According to the present invention configured as described above, when the EGR rate is equal to or higher than a predetermined value and the EGR concentration during intake is high, the throttle valve and the multi-cylinder are corrected by closing the maximum opening of the throttle valve. It is possible to cause a disturbance in the flow of fresh air with the engine. Then, by generating a turbulent flow of fresh air between the throttle valve and the multi-cylinder engine, that is, in the vicinity of the EGR inlet, it is possible to promote mixing of fresh air and the recirculated exhaust gas. Thereby, the amount of exhaust gas supplied to each cylinder of the multi-cylinder engine can be made more uniform.

  In the present invention, preferably, a turbocharger including a turbine provided in the exhaust system, a compressor provided in the intake system and connected to the turbine, and bypassing the compressor on the exhaust system. A waste gate valve provided on the bypass passage, and when the opening degree of the throttle valve is corrected by the opening degree control device, the opening degree of the waste gate valve is reduced.

  According to the present invention configured as described above, when the opening degree of the throttle valve is corrected to be closed, the opening degree of the waste gate valve is reduced, and the rotational speed of the turbine is increased. The supply pressure can be increased. Thereby, it is possible to prevent the opening amount of the throttle valve from being closed and the intake amount to the multi-cylinder engine from becoming insufficient.

  In this case, it is preferable that the amount by which the maximum opening of the throttle valve is corrected to be closed increases as the EGR rate increases.

  Thereby, when the EGR rate is high, the turbulent flow generated in the vicinity of the EGR inlet can be further increased. Therefore, even when the EGR rate is high, the amount of exhaust supplied to each cylinder can be made uniform.

  As described above, according to the present invention, EGR and fresh air are mixed and the EGR gas is uniformly distributed to each cylinder of the multi-cylinder engine without increasing the size of the engine, particularly when the EGR concentration is high. it can.

1 is a configuration diagram of an engine system equipped with an engine control device according to an embodiment of the present invention. It is a flowchart which shows operation | movement of the engine system by embodiment of this invention. It is a graph which shows the relationship between an EGR rate and upper limit TVOlim. It is a flowchart which shows the supercharging pressure control at the time of carrying out the closing correction of the opening degree of a throttle valve. The example of the map which an engine system uses is shown.

  Hereinafter, an engine control apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an engine system equipped with an engine control device.

  As shown in FIG. 1, the engine system 100 mainly includes an intake passage 10 through which intake air (air) introduced from the outside passes, intake air supplied from the intake passage 10, and a fuel injection valve 23 described later. It has an engine 20 (for example, a gasoline engine) that burns an air-fuel mixture with the supplied fuel to generate vehicle power, and an exhaust passage 30 that discharges exhaust gas generated by combustion in the engine 20.

  In the intake passage 10, an air cleaner 2 that purifies intake air introduced from the outside, and a compressor 4 a of the turbocharger 4 that compresses the intake air passing therethrough and raises the intake air pressure in order from the upstream side. An intercooler 9 that cools intake air, a throttle valve 11 that adjusts the amount of intake air that passes through, and a surge tank 13 that temporarily stores intake air supplied to the engine 20 are provided.

  The throttle valve 11 is controlled so that its opening degree is between 0% and 100% based on the fresh air flow rate required by the engine 20. When the opening degree of the throttle valve 11 is 0%, the throttle valve 11 is controlled to be in a posture orthogonal to the direction in which the intake passage 10 extends to block the flow of fresh air toward the downstream side of the intake passage 10. On the other hand, when the opening degree of the throttle valve 11 is 100%, the throttle valve 11 is controlled to be in a posture parallel to the direction in which the intake passage 10 extends, and fresh air is not obstructed by the throttle valve 11. It flows with a smooth air flow toward the downstream side.

  The intake passage 10 is provided with an air bypass passage 6 for bypassing the compressor 4a of the turbocharger 4 and flowing intake air. Specifically, one end of the air bypass passage 6 is connected to the intake passage 10 downstream of the compressor 4a and upstream of the throttle valve 11, and the other end is connected to the intake passage 10 upstream of the compressor 4a. Yes. An air bypass valve 7 that controls intake air flowing through the air bypass passage 6 is provided on the air bypass passage 6.

  The engine 20 mainly supplies an intake valve 22 for introducing the intake air supplied from the intake passage 10 into the combustion chamber 21, a fuel injection valve 23 for injecting fuel toward the combustion chamber 21, and a supply to the combustion chamber 21. Spark plug 24 for igniting the mixture of intake air and fuel, a piston 27 reciprocating by combustion of the air-fuel mixture in the combustion chamber 21, a crankshaft 28 rotated by reciprocating motion of the piston 27, and combustion And an exhaust valve 29 for discharging exhaust gas generated by combustion of the air-fuel mixture in the chamber 21 to the exhaust passage 30. The engine 20 is, for example, a four-cylinder engine that includes four combustion chambers 21 and four pistons 27.

  The exhaust passage 30 is rotated by exhaust gas passing through in order from the upstream side, and the turbine 4b of the turbocharger 4 that drives the compressor 4a as described above by this rotation, and the difference generated in the exhaust passage 30. A muffler 38 for processing the sound is provided. Although not shown, an exhaust purification catalyst having an exhaust gas purification function, such as a NOx catalyst, a three-way catalyst, or an oxidation catalyst, is provided between the turbocharger 4 and the muffler 38. Yes.

  Further, the exhaust passage 30 is provided with a turbine bypass passage 35 that flows the exhaust gas bypassing the turbine 4 b of the turbocharger 4. The turbine bypass passage 35 is a passage that connects the upstream side of the turbine 4b of the exhaust passage 30 and the downstream side of the turbine 4b while bypassing the turbine 4b. A waste gate valve 36 that controls the exhaust gas flowing through the turbine bypass passage 35 is provided on the turbine bypass passage 35. The waste gate valve 36 opens and closes the turbine bypass passage 35 under control by PCM, which will be described later, or connects the upstream side and the downstream side of the turbine 4b of the exhaust passage 30 so as not to pass through the turbine 4b. .

  Further, an exhaust gas recirculation (EGR) passage 40 is provided between the exhaust passage 30 and the intake passage 10 for circulating the exhaust discharged from the engine 20 to the intake passage. The EGR passage 40 branches from the exhaust passage 30 between the engine 20 and the turbine 4 b of the turbocharger 4, and joins the intake passage 10 between the throttle valve 11 and the surge tank 13. The EGR passage 40 is provided with an EGR cooler 42 for cooling the exhaust gas flowing into the EGR passage 40, and the intake passage 10 side of the EGR cooler 42, and the amount of exhaust gas introduced into the intake passage 10 is reduced. An EGR valve 44 to be controlled is provided.

  The engine system further includes a PCM (Power Control Module) 51 for controlling the entire system. The PCM 51 is, for example, a first pressure sensor 53 that detects the pressure in the intake passage 10 upstream of the throttle valve 11 in the intake passage 10, and a flow sensor 55 that detects the flow rate of fresh air that has passed through the throttle valve 11. The detection value is received from the second pressure sensor 57 that detects the pressure in the surge tank 13, the EGR sensor 59 that detects the EGR amount in the EGR passage 40, and the like.

  FIG. 2 is a flowchart showing the operation of the engine system described above.

  When a series of processes starts during operation of the engine, the engine system 100 detects the pressures on the upstream side and the downstream side of the throttle valve 11 in step S1. This process is performed by the PCM 51 reading the detection values of the first pressure sensor 53 and the second pressure sensor 57.

  Next, in step S2, the engine system 100 calculates a required throttle passage flow rate ga0. In this process, for example, the PCM 51 calculates the engine torque request from the accelerator opening, and calculates the amount of fresh air required (the amount of fresh air per unit time passing through the throttle) from the calculated torque request value. calculate. Then, the PCM 51 detects the pressure in the surge tank 13 based on the detection value of the second pressure sensor 57, and corrects the calculated amount of fresh air with the detected pressure in the surge tank 13, so that the transient is detected. The amount of fresh air to be passed through the throttle valve 11 in consideration, that is, the required throttle passage flow rate ga0 is calculated.

  Next, in step S3, the engine system 100 calculates the amount of fresh air that has actually passed through the throttle valve 11, that is, the actual throttle passage flow rate ga1. This process is executed by the PCM 51 detecting the current throttle opening and the pressure difference between the upper and lower portions of the throttle valve 11 and applying the detected values to Bernoulli's theorem.

  Next, in step S4, the engine system 100 determines whether or not EGR control is being performed. For example, when the EGR valve 44 is opened in the high load operation region of the engine 20 and the exhaust gas is circulated from the exhaust passage 20 via the EGR passage 40, the process proceeds to step S5.

  In step S5, the engine system 100 sets an upper limit value TVOlim of the opening degree of the throttle valve 11. That is, when exhaust gas is recirculated through the EGR passage 40, an upper limit value is set for the opening degree of the throttle valve 11, and the maximum opening degree of the throttle valve 11 is set regardless of the required load from the engine 20. Is limited. The value of the upper limit value TVOlim is a value obtained experimentally, and is determined, for example, as in the graph shown in FIG.

  FIG. 3 is a graph showing the relationship between the EGR rate and the upper limit value TVOlim. The vertical axis shows the upper limit value TVOlim (%), and the horizontal axis shows the EGR rate (%). The degree of dispersion in the exhaust passage when the exhaust gas is circulated to the intake passage 10 varies depending on the position and shape of the EGR inlet at the end of the EGR passage 40. The upper limit value TVOlim is experimentally determined according to the position and shape of the EGR inlet, and is recorded in the PCM 51. For example, in a certain engine or an engine with low exhaust dispersion, the relationship between the EGR rate and the upper limit value TVOlim is indicated by a line L1. In an engine with a low exhaust dispersion, the upper limit value TVOlim is set to 70%, for example, when the EGR rate is relatively low and E1%. Then, the upper limit value TVOlim becomes lower as the EGR rate becomes higher. That is, in an engine with low exhaust dispersion, turbulence is generated downstream of the throttle valve 11 during exhaust gas circulation since the amount of exhausted exhaust gas is small. Therefore, in an engine with a low exhaust dispersion, the upper limit value TVOlim is set when the EGR rate is relatively low (E1%). Even if the engine has a low exhaust dispersion, if the EGR rate is lower than E1%, there is no need to consider the exhaust dispersion on the downstream side of the throttle valve 11, so the upper limit value TVOlim is set. Not.

  In an engine with a relatively high exhaust dispersion, the relationship between the EGR rate and the upper limit value TVOlim is indicated by a line L2. For engines with relatively high exhaust dispersion, even if the EGR rate is E1% or higher, the upper limit TVOlim is not set and the upper limit is set when the EGR rate is E2% or higher, which is higher than E1%. The value TVOlim is set. Thereby, when the EGR rate is higher than E1% and equal to or lower than E2%, the upper limit value TVOlim is not set, and the opening degree of the throttle valve 11 is controlled in accordance with the required load of the engine. The EGR rates E1% and E2% are values obtained experimentally and stored in the PCM 51, similarly to the upper limit value TVOlim. The engine system 100 sets the upper limit value TVOlim when the EGR rate is greater than or equal to the EGR rate (E1 or E2%) determined in accordance with the degree of engine exhaust dispersion. It has become.

  On the other hand, for example, when the EGR valve 44 is closed in the low load operation region of the engine 20 and the exhaust gas is not recirculated through the EGR passage 40, the process of step S5 is not performed, and step S6 is performed. Proceed to the subsequent processing.

  In step S6, the engine system 100 determines whether or not the requested throttle passage amount ga0 is equal to the actual throttle passage amount ga1. With this process, it can be determined whether or not the required throttle passage amount ga0 has been achieved. If it is determined in step S6 that the requested throttle passage amount ga0 and the actual throttle passage amount ga1 are equal, the series of processing is terminated, and the processing from step S1 is repeated again.

  On the other hand, if it is determined in step S6 that the requested throttle passage amount ga0 is not equal to the actual throttle passage amount ga1, the engine system 100 determines that the requested throttle passage amount ga0 is equal to the actual throttle passage amount ga1 in step S7. It is judged whether it is larger than. If it is determined in step S7 that the requested throttle passage amount ga0 is not larger than the actual throttle passage amount ga1, the amount of fresh air that passes through the throttle valve 11 is currently large in response to the request from the engine. In step S8, the opening degree of the throttle valve 11 is decreased, and the series of processes is terminated.

  If it is determined in step S7 that the required throttle passage amount ga0 is larger than the actual throttle passage amount ga1, the engine system 100 determines in step S9 that the current opening degree of the throttle valve 11 is greater than the upper limit value TVOlim. It is also determined whether or not the When the exhaust gas is not recirculated through the EGR passage 41 and the upper limit value TVOlim is not set in step S5, the current throttle opening is always smaller than the upper limit value TVOlim. to decide. The process of step S9 is performed in step S7 when the actual throttle passage amount ga1 is less than the required throttle passage amount ga0 and the amount of fresh air introduced is small with respect to the request of the engine 20. If it is determined in step S9 that the current opening degree of the throttle valve 11 is smaller than the upper limit value TVOlim, the opening degree of the throttle valve 11 is increased in step S10, and the series of processing ends.

  On the other hand, when it is determined in step S9 that the current opening degree of the throttle valve 11 is not smaller than the upper limit value TVOlim, the opening degree of the throttle valve 11 is changed to the upper limit value set in step S5 in step S11. Reduce to below TVOlim. Thereby, when the exhaust gas is circulated through the EGR passage 41, the opening degree of the throttle valve 11 can be corrected to be closed according to the EGR rate. And the opening degree after correction | amendment of the throttle valve 11 turns into an opening degree according to the graph shown in FIG. Then, by correcting the opening of the throttle valve 11, turbulent flow is generated on the downstream side of the throttle valve 11, promoting the mixing of fresh air in the intake passage 10 and the recirculated exhaust gas, and supplying it to each cylinder. The amount of exhausted air can be made more uniform.

  Thus, according to the present embodiment, when the EGR rate is equal to or higher than a predetermined value (for example, E1% or higher or E2% or higher) and the EGR concentration in the intake air is high, the required throttle valve 11 is temporarily required. Even if the opening degree is 100%, the fresh air flow can be disturbed between the throttle valve 11 and the multi-cylinder engine 20 by correcting the opening degree of the throttle valve 11 to be closed. Then, by generating a turbulent flow of fresh air between the throttle valve 11 and the multi-cylinder engine 20, that is, in the vicinity of the EGR introduction port, mixing of fresh air and the recirculated exhaust gas can be promoted. Thereby, the amount of exhaust gas supplied to each cylinder of the multi-cylinder engine 20 can be made more uniform.

  In addition, if the opening degree of the throttle valve 11 is reduced during the intake stroke, the amount of fresh air supplied to the engine 20 may be insufficient and the required torque cannot be satisfied. In such a case, it is preferable to achieve the required torque by increasing the supercharging pressure to the engine 20 while maintaining the opening of the throttle valve 11 at the corrected opening.

  FIG. 4 is a flowchart showing the supercharging pressure control when the opening degree of the throttle valve is corrected to be closed.

  As shown in FIG. 4, when a series of processes starts, the engine system reads the accelerator opening, the engine speed, and the amount of fresh air flowing into the intake passage 10 in step S31. This process is performed by the PCM 51 reading detection values of various sensors (not shown).

  Next, in step S32, the engine system calculates a torque request value based on the accelerator opening, and in step S33 calculates a charging efficiency CEa to the engine 20 necessary to achieve the torque request value. By these steps S32 and S33, the charging efficiency CEa necessary to meet the request from the driver based on the accelerator opening is calculated.

  Next, in step S34, the engine system determines a target EGR rate based on the engine speed and the engine load. This process is performed by referring to a map stored in advance in the PCM 51 based on the read engine speed and engine load.

  Next, in step S35, the engine system calculates the charging efficiency CEb after correcting the opening of the throttle valve 11 based on the upper limit value TVOlim set based on the determined EGR rate. Specifically, in order to calculate the charging efficiency CEb, the throttle passage flow rate based on the throttle opening to be restricted is calculated, and the intake manifold air amount is calculated from the throttle passage flow rate. The charging efficiency CEb is calculated based on the calculated intake manifold air amount.

  Next, in step S36, the engine system compares the charging efficiency CEa calculated in step S33 with the charging efficiency CEb calculated in step S35, and the charging efficiency CEa is a throttle valve based on the upper limit value TVOlim considering the EGR rate. It is determined whether or not the charging efficiency CEb after the opening correction is larger. If the charging efficiency CEa is not greater than the charging efficiency CEb, that is, if they are equal, in step S37, the engine system sets the value of the charging efficiency CEa as the charging efficiency CE used in the continued calculation. On the other hand, when the charging efficiency CEb is smaller than the charging efficiency CEa, that is, when the opening degree of the throttle valve 11 is substantially limited based on the upper limit value TVOlim, in step S38, the engine system is used for continued calculation. As the filling efficiency CE to be performed, the value of the filling efficiency CEb is set.

  Next, in step S39, the engine system calculates a required pressure Pa (or required intake manifold pressure) in the surge tank 13 based on the set charging efficiency CE.

  Next, in step S40, the engine system reads the required throttle front-rear differential pressure. In this process, a map (see FIG. 5) in which a differential pressure before and after the throttle that satisfies both the fuel efficiency and the throttle response is experimentally obtained in advance from the current engine speed and charging efficiency is stored in the PCM 51 in advance. And is executed by reading the map.

  Next, in step S41, the engine system calculates a correction amount Pb for the differential pressure across the throttle valve 11. The front-rear differential pressure correction amount Pb is a pressure necessary to compensate for the charging efficiency (absolute value of the difference between CEa and CEb) which has been reduced by closing correction of the opening degree of the throttle valve 11. Therefore, when there is no difference between CEa and CEb, the correction amount Pb is zero. In this process, specifically, the reduced charging efficiency is converted into a reduced flow rate, and a correction amount Pb of the front-rear differential pressure is obtained based on this flow rate and the throttle valve opening (passage opening area).

  Next, in step S42, the engine system adds the differential pressure Pb1 read out in step S40 and the correction amount Pb2 calculated in step S41, and finally becomes necessary by correcting the opening of the throttle valve 11 to be closed. A differential pressure Pb before and after the throttle valve 11 is calculated. In step S43, the engine system compensates for the torque drop when the opening of the throttle valve 11 is corrected to close based on the intake manifold pressure Pa calculated in step S39 and the correction amount Pb2 calculated in step S42. The required target boost pressure Pc of the engine is calculated.

  As a specific means for controlling the supercharging pressure, for example, there is a method of adjusting the opening degree of the waste gate valve 36 provided in the turbine bypass passage 35. That is, if the opening degree of the waste gate valve 36 is reduced or fully closed, the turbine bypass passage 35 is partially reduced or shut off, so that the amount of exhaust gas flowing toward the turbine 4b increases and the turbine 4b Output increases. And if the output of the turbine 4b increases, the supercharging pressure in the intake passage 10 by the compressor 4a will rise. Conversely, when the opening degree of the waste gate valve 36 is increased or fully opened, the turbine bypass passage 35 is expanded, so that the amount of exhaust gas flowing toward the turbine 4b decreases and the output of the turbine 4b decreases. . And if the output of the turbine 4b decreases, the supercharging pressure in the intake passage 10 by the compressor 4a will fall.

  Even if the air supply amount to the engine 20 is reduced by closing the throttle valve 11 by the supercharging pressure control as described above, the supercharging pressure to the engine 20 is increased by a configuration other than the throttle valve 11. Can do. Thus, the required torque can be achieved by increasing the supercharging pressure to the engine 20 while maintaining the opening of the throttle valve 11 at the corrected opening.

4 Turbocharger 10 Intake passage 11 Throttle valve 11
13 Surge tank 20 Multi-cylinder engine 40 EGR passage 51 PCM
100 engine system

Claims (3)

A control device for a multi-cylinder engine,
A throttle valve provided in the intake system of the multi-cylinder engine for adjusting the amount of fresh air introduced downstream;
An EGR inlet provided between the multi-cylinder engine and the throttle valve;
An opening degree control device for controlling the opening degree of the throttle valve,
When the exhaust gas is recirculated from the EGR introduction port to the intake system and the EGR rate is equal to or higher than a predetermined value, the opening degree control device is configured so that the throttle valve A multi-cylinder engine controller that compensates for the maximum opening. A turbocharger comprising a turbine provided in the exhaust system, and a compressor provided in the intake system and connected to the turbine;
A wastegate valve provided on a bypass passage that bypasses the compressor on the exhaust system,
The multi-cylinder engine control device according to claim 1, wherein when the opening degree of the throttle valve is corrected to be closed by the opening degree control device, the opening degree of the waste gate valve is reduced.   The control device for a multi-cylinder engine according to claim 2, wherein an amount for closing the maximum opening of the throttle valve is increased as the EGR rate is increased.

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