JP2010038093A - Control device for internal combustion engine with supercharger - Google Patents

Abstract

When an engine is operated in an operation region in which a turbine passing gas flow rate can be ensured without excessively reducing a rotation speed of a supercharger, a wastegate valve is set so that the turbine passing gas flow rate matches a gas flow rate threshold value. By reducing the exhaust pressure, the exhaust pressure is reduced to reduce exhaust loss and to ensure the acceleration response performance of the engine.
An internal combustion engine with a supercharger includes a wastegate valve (WGV) and an actuator a which are interposed in a bypass passage 55 that bypasses a turbine 46b of the supercharger 46. When the engine is operating in the first operating region where the intake air flow rate is equal to or higher than a predetermined gas flow rate threshold value, the control device controls the opening degree of the WGV 54 so that the turbine passing gas flow rate becomes the gas flow rate threshold value. When the engine is operated in the second operation region where the intake air flow rate is smaller than the gas flow rate threshold, the control device closes the bypass passage 55 by the WGV 54.
[Selection] Figure 4

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger capable of reducing exhaust loss (extrusion loss) by controlling a waste gate valve opening (and / or exhaust valve opening timing).

  It is known to mount a turbocharger on an internal combustion engine for the purpose of improving the output of the internal combustion engine. The supercharger includes a turbine that is provided in the exhaust passage and is rotated by using a flow of exhaust gas flowing in the exhaust passage, and a compressor that is provided in the intake passage and rotates integrally with the turbine. The supercharger compresses intake air by rotating the compressor and increases the intake air flow rate (performs supercharging).

  An exhaust passage of an internal combustion engine having a supercharger is provided with a bypass passage through which exhaust gas flows so as to bypass the turbine. A waste gate valve is disposed in the bypass passage. The wastegate valve adjusts the amount of exhaust gas flowing into the turbine (hereinafter also referred to as “turbine passing gas flow rate”) by diverting a part of the exhaust gas flowing in the exhaust passage to the bypass passage. Generally, the wastegate valve is opened when the rotational speed of the turbine is excessively increased. Thereby, since the turbine passing gas flow rate is decreased, the turbine rotation speed is decreased. As a result, it is avoided that the supercharging pressure becomes excessive and / or the pressure in the exhaust passage (hereinafter also referred to as “exhaust pressure”) becomes excessive, so that the internal combustion engine and / or the supercharger is avoided. Damage to itself is avoided.

  On the other hand, the wastegate valve is also used for suppressing an increase in exhaust loss (push-out loss) due to an increase in exhaust pressure. The turbine disposed in the exhaust passage hinders the passage of exhaust gas discharged from the combustion chamber, which causes the exhaust pressure to increase. As exhaust pressure increases, exhaust loss increases and the efficiency of the internal combustion engine decreases.

Therefore, one of the conventional techniques calculates exhaust loss (pumping loss) based on the supercharging pressure and exhaust pressure in order to reduce exhaust loss, and the waist is set so that the exhaust loss becomes the target exhaust loss. The opening degree of the gate valve is controlled (for example, refer to Patent Document 1).
JP 2007-192155 A

  However, the above conventional technique focuses on exhaust loss and opens the wastegate valve regardless of the amount of intake air per unit time (hereinafter also referred to as “intake air flow rate”), which has a strong correlation with the turbine rotation speed. Since the degree is adjusted, the wastegate valve may be opened even when the intake air flow rate is relatively small. In this case, the “turbine passing gas flow rate that is the flow rate of the exhaust gas passing through the turbine” and the “exhaust pressure” are relatively reduced, so that the rotational speed of the turbine is excessively reduced. When the rotational speed of the turbine is lowered, a supercharging delay (turbo lag) when an acceleration request is subsequently made becomes long, and there arises a problem that the acceleration performance of the internal combustion engine is not good.

  The present invention has been made to address the above problems. Accordingly, one of the objects of the present invention is to provide an operation region in which the “turbine passing gas flow rate in which the rotation speed of the supercharger does not decrease excessively” can be secured (that is, an operation in which the intake air flow rate is equal to or higher than the gas flow rate threshold When the engine is operated in (region), the exhaust pressure is reduced by reducing the exhaust pressure by opening the waste gate valve (controlling the opening degree) so that the actual gas flow rate through the turbine matches the gas flow rate threshold. Another object of the present invention is to provide a control device for an internal combustion engine that can ensure acceleration response performance of the engine. In other words, the present invention relates to an engine in an operation region in which an exhaust gas flow rate larger than a “minimum turbine passage gas flow rate threshold value” that can maintain the rotational speed of the supercharger at a predetermined rotational speed (speed at which acceleration response performance does not deteriorate) is obtained. Is operated, the opening degree of the wastegate valve is adjusted so that the actual turbine passing gas flow rate is maintained at the turbine passing gas flow rate threshold value.

  More specifically, the control device for an internal combustion engine with a supercharger according to the present invention is applied to an internal combustion engine with a supercharger that includes a supercharger, a wastegate valve, and a wastegate valve drive mechanism. The

  The supercharger is disposed in a turbine disposed in an exhaust pipe that forms an “exhaust passage communicating with a combustion chamber of an internal combustion engine” and an intake pipe that forms an “intake passage communicating with a combustion chamber”. And a compressor. The compressor rotates integrally with the turbine.

  The waste gate valve is interposed in a bypass passage that bypasses the turbine. One end of the bypass passage is connected (communication) to “a position upstream of the turbine of the exhaust pipe”. The other end of the bypass passage is connected (communication) to “a position downstream of the turbine in the exhaust pipe”.

  The waste gate valve drive mechanism changes the opening of the waste gate valve in accordance with an instruction. Thereby, the said wastegate valve drive mechanism changes the flow-path cross-sectional area of the said bypass channel.

  Furthermore, this control device is characterized by comprising waste gate valve opening control means.

  When the engine is operated in the first operation region where the intake air flow rate of the engine is equal to or higher than a predetermined gas flow rate threshold, the wastegate valve opening degree control means indicates that “the turbine is the flow rate of exhaust gas passing through the turbine. An instruction for controlling the opening degree of the waste gate valve so that the passing gas flow rate becomes the same gas flow rate threshold value is given to the waste gate valve drive mechanism.

  Further, when the engine is operated in the second operation region in which the intake air flow rate of the engine is smaller than the gas flow rate threshold, the waste gate valve opening degree control means indicates that “the waste gate valve closes the bypass passage. Is given to the wastegate valve drive mechanism (instruction to set the wastegate valve opening to 0).

  FIG. 1 is a graph showing a first operation region and a second operation region. The horizontal axis of the graph shown in FIG. 1 is the engine rotational speed NE, and the vertical axis is the engine load (more precisely, the load factor which is a filling factor, which is substantially equal to the indicated torque). A curve C1 indicates an operating state in which the intake air amount (intake air flow rate) per unit time becomes the above-described “gas flow rate threshold value”. The first operation region is a region above the curve C1, that is, a region where the intake air flow rate becomes larger than the gas flow rate threshold value. The second operation region is a region below the curve C1, that is, a region where the intake air flow rate becomes smaller than the gas flow rate threshold value.

  When the wastegate valve is closed, the intake air flow rate and the turbine passing gas flow rate are substantially equal. Therefore, when the intake air flow rate is the gas flow rate threshold value (curve C1) and the wastegate valve is closed, the turbine passing gas flow rate becomes equal to the gas flow rate threshold value, and a sufficient amount of exhaust gas flows into the turbine. is doing. As a result, the turbine rotation speed is maintained at a rotation speed at which supercharging can be performed quickly when a “subsequent acceleration request” occurs.

  In other words, if the wastegate valve is completely closed when the engine is operating in the first operating region, the turbine passage gas flow rate will be excessive, so the turbine rotation speed will be higher than necessary. Become. As a result, the exhaust pressure becomes excessive. For this reason, exhaust loss (extrusion loss) when exhaust gas is discharged from the combustion chamber increases. That is, as indicated by the broken line L1 in FIG. 2 which is a PV diagram, the pressure in the combustion chamber near the expansion bottom dead center BDC, which is the exhaust valve opening timing, becomes high. Pressure increases. Therefore, the work is reduced by the portion indicated by the region S1.

  On the other hand, according to the control device of the present invention, when the engine is operated in the first operation region, the wastegate valve is opened so that the actual gas flow rate through the turbine becomes the gas flow rate threshold value.

  As a result, even if the engine is operated in the first operating region, the exhaust gas pressure decreases because the turbine passing gas flow rate does not become excessive. Therefore, exhaust loss when exhaust gas is discharged from the combustion chamber is reduced. That is, since the exhaust pressure decreases, as shown by the solid line L2 in FIG. 2, the pressure in the combustion chamber near the expansion bottom dead center BDC, which is the exhaust valve opening timing, decreases, and combustion occurs even after the exhaust stroke starts. The room pressure becomes low. As a result, the work loss of the portion indicated by the region S1 is avoided. Further, the turbine rotation speed is maintained at “the rotation speed at which supercharging can be performed with good response to the acceleration request”. Therefore, the turbo lag does not become long. From the above, the present control device can operate the engine efficiently without sacrificing the acceleration performance of the engine.

  In this case, it is desirable that the present control device includes an exhaust valve opening timing changing mechanism and an exhaust valve opening timing control means.

  The exhaust valve opening timing changing mechanism changes the opening timing of the exhaust valve of the engine according to an instruction.

  The exhaust valve opening timing control means is an instruction for setting the exhaust valve opening timing to the first exhaust valve opening timing in the vicinity of the expansion bottom dead center when the engine is operated in the first operating region. Is provided to the exhaust valve opening timing changing mechanism.

  Further, the exhaust valve opening timing control means sets the exhaust valve opening timing to a second exhaust position that is advanced from the first exhaust valve opening timing when the engine is operated in the second operation region. An instruction for setting the valve opening timing is given to the exhaust valve opening timing changing mechanism.

  As described above, when the engine is operated in the second operation region, it is not a good idea to open the wastegate valve from the viewpoint of reducing the turbo lag of the supercharger. However, even in the second operation region, there is a region where the exhaust pressure is high at the exhaust valve opening timing, and also in this case, exhaust loss increases. Therefore, in such a region, the exhaust valve opening timing is advanced (accelerated) from the first exhaust valve opening timing to the second exhaust valve opening timing as in the above configuration.

  The effect of this will be described with reference to “FIG. 3 which is a PV diagram similar to FIG. 2”. When the engine is operated in the second operation region, the exhaust valve opening timing is “expanded and dead. It is set to “second exhaust valve opening timing EVO2” slightly advanced from “first exhaust valve opening timing EVO1” in the vicinity of the point. As a result, in the latter half of the expansion stroke, the pressure in the combustion chamber starts to drop early, so that the work is reduced by the amount indicated by the area S2. On the other hand, after the expansion bottom dead center, the pressure in the combustion chamber decreases, so that the exhaust loss is reduced and the work is increased by the amount indicated by the area S3. At this time, the second exhaust valve opening timing EVO2 is set to a timing when the area S3 is larger than the area S2. As a result, the work increases by an amount obtained by subtracting the area S2 from the area S3 (S3-S2). Therefore, the present control device can operate the engine more efficiently.

  Hereinafter, an embodiment of a “control device for an internal combustion engine with a supercharger (hereinafter also simply referred to as“ control device ”)” according to the present invention will be described with reference to the drawings.

<Configuration>
FIG. 4 shows a schematic configuration of a system in which this control device is applied to a piston reciprocating spark ignition type, multi-cylinder (4 cylinders), 4-cycle, internal combustion engine 10. FIG. 4 shows only a cross section of a specific cylinder, but the other cylinders have the same configuration.

  The engine 10 includes a cylinder block portion 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like, a cylinder head portion 30 fixed on the cylinder block portion 20, and “fuel and air are supplied to the cylinder block portion 20. An intake system 40 for supplying the “containing mixed gas” and an exhaust system 50 for releasing the exhaust gas discharged from the cylinder block unit 20 to the outside are included.

  The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. The upper surfaces of the cylinder 21 and the piston 22 form a combustion chamber 25 together with the cylinder head portion 30.

  The cylinder head unit 30 includes an intake port 31 that communicates with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake valve control device 33 that opens and closes the intake valve 32, an exhaust port 34 that communicates with the combustion chamber 25, an exhaust An exhaust valve 35 for opening and closing the port 34, an exhaust valve control device 36 (exhaust valve opening timing changing mechanism) for opening and closing the exhaust valve 35, an ignition plug 37 provided in each cylinder, and a high voltage applied to each ignition plug 37 An igniter 38 including an ignition coil that is generated, and an injector (fuel injection valve) 39 that injects fuel of the indicated fuel supply amount included in the instruction signal into the intake port 31 of each cylinder.

  The intake valve control device 33 adjusts the relative rotation angle (phase angle) between the intake cam shaft and the intake cam (not shown) by hydraulic pressure, as described in, for example, Japanese Patent Application Laid-Open No. 2007-303423. A well-known configuration is provided for controlling the valve opening timing of the intake valve 32 (intake valve opening timing).

  The exhaust valve control device 36 has the same configuration as the intake valve control device 33. That is, the exhaust valve control device 36 has a known configuration that adjusts and controls the relative rotation angle (phase angle) between the exhaust camshaft and the exhaust cam (not shown) by hydraulic pressure, and the exhaust valve 35 is opened ( The exhaust valve opening timing) can be changed.

  The intake system 40 includes an intake manifold 41, an intake pipe 42, an air filter 43, a throttle valve 44 and a throttle valve actuator 44a, an intercooler 45, a compressor 46a of a supercharger 46, a compressor bypass passage 47, and an air bypass valve 48. .

  The intake manifold 41 is connected to the intake port 31 of each cylinder. More specifically, the intake manifold 41 includes a plurality of branch portions 41a connected to each intake port 31, and a surge tank portion 41b in which those branch portions are gathered.

  One end of the intake pipe 42 is connected to the surge tank 41b. The intake manifold 41 and the intake pipe 42 constitute an intake passage.

The air filter 43 is provided at the other end of the intake pipe 42.
The throttle valve 44 is rotatably provided in the intake pipe 42, and changes the opening cross-sectional area of the intake passage formed by the intake pipe 42 by rotating. The throttle valve actuator (throttle valve drive means) 44a is formed of a DC motor, and rotates the throttle valve 44 in response to an instruction signal.

  The intercooler 45 is disposed in the intake pipe 42 at a position upstream of the throttle valve 44. The intercooler 45 cools the intake air passing through the intake passage. Engine cooling water is guided to the intercooler 45 through a cooling water introduction path (not shown), and the intake air is cooled by the engine cooling water.

  The compressor 46 a of the supercharger 46 is disposed in the intake pipe 42 at a position upstream of the intercooler 45.

The compressor bypass passage 47 is disposed in the intake pipe 42 so as to bypass the compressor 46 a upstream of the intercooler 45. That is, one end of the compressor bypass passage 47 is connected to “a position upstream of the compressor 46 a of the intake pipe 42”. The other end of the compressor bypass passage 47 is connected to “a position downstream of the compressor 46 a of the intake pipe 42”.
The air bypass valve 48 is disposed in the compressor bypass passage 47. The air bypass valve 48 is opened and closed by an instruction signal. The air bypass valve 48 is opened when the throttle valve 44 is closed, for example, when the engine 10 is decelerating. As a result, the intake air downstream of the compressor 46a can return to the upstream of the compressor 46a through the compressor bypass passage 47. As a result, it is possible to reduce the pressure downstream of the compressor 46a that has rapidly increased when the throttle valve 44 is closed. As a result, damage to the compressor 46a can be avoided.

  The exhaust system 50 includes an exhaust manifold 51, an exhaust pipe 52, a turbine 46 b of the supercharger 46, a turbine bypass passage 55, a waste gate valve (WGV) 54, a waste gate valve actuator 54 a and a catalyst 53.

The exhaust manifold 51 includes a plurality of branch portions connected to each exhaust port and a collective portion in which the branch portions are gathered.
The exhaust pipe 52 is connected to a collecting portion of the exhaust manifold 51. The exhaust manifold 51, the exhaust pipe 52, a turbine bypass passage 55, which will be described later, and the exhaust port 34 constitute an exhaust path through which the exhaust gas passes.

  The turbine 46 b of the supercharger 46 is disposed in the exhaust pipe 52 at a position downstream of the exhaust manifold 51. The turbine 46b is connected with the compressor 46a via the rotating shaft 46c. That is, the turbine 46b and the compressor 46a rotate integrally. The turbine 46b is rotated by exhaust gas discharged from the combustion chamber 25 and flowing into the turbine 46b (housing of the turbine 46b). Thereby, the compressor 46a performs a supercharging operation.

  The turbine bypass passage (bypass passage) 55 is connected to the exhaust pipe 52 so as to bypass (detour) the turbine 46 b upstream of the catalyst 53. That is, the turbine bypass passage 55 is connected by a bypass pipe having one end connected to the “upstream position from the turbine 46 b” of the exhaust pipe 52 and the other end connected to the “downstream position from the turbine 46 b” of the exhaust pipe 52. It is configured.

  The wastegate valve 54 is disposed (intervened) in the turbine bypass passage 55. The wastegate valve 54 is configured such that the opening degree thereof can be adjusted, and the flow passage cross-sectional area of the turbine bypass passage 55 can be changed by changing the opening degree thereof. In other words, the waste gate valve 54 divides a part of the exhaust gas flowing in the exhaust pipe 52 into the bypass passage 55 when the waste gate valve 54 is opened, so that the amount of exhaust gas flowing into the turbine (that is, the turbine) The passing gas flow rate) can be adjusted.

  The wastegate valve actuator 54a (waistgate valve drive mechanism) is composed of an electric motor, and opens and closes the wastegate valve 54 in response to an instruction signal (changes the opening degree of the wastegate valve 54). That is, the wastegate valve actuator 54a changes the flow passage cross-sectional area of the turbine bypass passage 55 by changing the opening degree of the wastegate valve 54 in accordance with the instruction, thereby adjusting the flow rate of gas passing through the turbine. ing. When the turbine passing gas flow rate decreases, the exhaust pressure is reduced. Thereby, exhaust loss (extrusion loss) is reduced.

  The catalyst 53 is a known three-way catalyst. The catalyst 53 is disposed in the exhaust pipe 52 at a downstream position of the turbine 46b.

  The control device further includes a throttle valve position sensor 61, a hot-wire air flow meter 62, an engine speed sensor 63, an accelerator opening sensor 64, an air-fuel ratio sensor 65, and an electric control device 70.

The throttle valve position sensor 61 detects the opening of the throttle valve 44 and outputs a signal representing the throttle valve opening TA.
The hot-wire air flow meter 62 detects the mass flow rate of the intake air flowing through the intake pipe 42 and outputs a signal representing the mass flow rate (intake air flow rate per unit time of the engine 10) GA.

  The engine rotation speed sensor 63 outputs a signal having a narrow pulse every time the crankshaft 24 rotates 5 ° and a signal having a wide pulse every time the crankshaft 24 rotates 360 °. A signal output from the engine rotational speed sensor 63 is converted into a signal representing the engine rotational speed NE by the electric control device 70. Further, the electric control device 70 acquires the crank angle (absolute crank angle) of the engine 10 based on signals from the engine rotational speed sensor 63 and a cam position sensor (not shown).

The accelerator opening sensor 64 detects the operation amount of the accelerator pedal AP operated by the driver, and outputs a signal indicating the operation amount Accp of the accelerator pedal.
The air-fuel ratio sensor 65 detects the air-fuel ratio of the exhaust gas discharged from each combustion chamber 25 (gas reaching the air-fuel ratio sensor 65), and outputs a signal representing the air-fuel ratio abf.

  The electric control device 70 includes “a CPU 71, a ROM 72, a RAM 73, a backup RAM 74 that stores data while the power is turned on and holds the stored data even while the power is shut off, and an interface 75 including an AD converter. Etc. ".

  An interface 75 of the electric control device 70 is connected to the sensors 61 to 65 and supplies signals from the sensors 61 to 65 to the CPU 71. The interface 75 sends an instruction signal (drive signal) to the igniter 38 of each cylinder, the injector 39 corresponding to each cylinder, the throttle valve actuator 44a, the air bypass valve 48, the wastegate valve actuator 54a, etc. according to the instruction of the CPU 71. It is supposed to be.

<Outline of exhaust loss reduction control by this controller>
Next, an outline of the “exhaust loss reduction control” of the control device configured as described above will be described with reference to FIGS. 5, 2, and 3.

  FIG. 5 is a graph showing the operation region 1, the operation region 2, and the operation region 3. The horizontal axis of the graph shown in FIG. 5 is the engine rotational speed NE, and the vertical axis is the engine load KL (more precisely, the load factor, which is a filling factor, approximately equal to the indicated torque). A curve C1 shows an operation state in which the intake air amount (intake air flow rate) per unit time becomes a predetermined “gas flow rate threshold value”. The “turbine passing gas flow rate”, which is the flow rate of exhaust gas flowing into the turbine 46b and passing through the turbine 46b, is substantially proportional to the rotational speed of the turbine 46b (and the compressor 46a). The gas flow rate threshold value is rapid when the exhaust gas equal to the gas flow rate threshold value flows into the turbine 46b and the turbine 46b (and the compressor 46a) rotates at a sufficiently high rotational speed and thereafter an acceleration operation is performed. This is the turbine passage gas flow rate that can increase the supercharging pressure.

  The operation region 1 in FIG. 5 corresponds to the first operation region in FIG. That is, the operation region 1 is a region above the curve C1 and is a region where the intake air flow rate becomes larger than the gas flow rate threshold value. A region including the operation region 2 and the operation region 3 in FIG. 5 corresponds to the second operation region in FIG. 1. That is, the region where the operation region 2 and the operation region 3 are combined is a region below the curve C1 and the region where the intake air flow rate is smaller than the gas flow rate threshold value. Further, the operation region 3 is a low intake air flow rate region in which the exhaust pressure does not cause a large exhaust loss, as will be described in detail later.

(Operation area 1)
By the way, when the waste gate valve 54 is closed (that is, the opening degree of the waste gate valve 54 is 0 and the turbine bypass passage 55 is completely closed), the intake air flow rate and the turbine passing gas flow rate are: Substantially equal. Therefore, when the intake air flow rate is the gas flow rate threshold (curve C1), when the wastegate valve 54 is closed, the turbine passing gas flow rate becomes equal to the gas flow rate threshold value, and a sufficient amount of exhaust gas is present in the turbine 46b. Inflow. As a result, the turbine rotation speed is maintained at a rotation speed at which supercharging can be performed quickly when a “subsequent acceleration request” occurs.

  In other words, if the wastegate valve 54 is completely closed when the engine 10 is operated in the operation region 1, the turbine passage gas flow rate becomes excessive, so the turbine rotation speed is higher than necessary. become. As a result, the exhaust pressure becomes excessive. For this reason, exhaust loss (extrusion loss) when exhaust gas is discharged from the combustion chamber 25 increases. That is, as indicated by the broken line L1 in FIG. 2 which is a PV diagram (a diagram showing the relationship between the combustion chamber pressure and the combustion chamber volume), the exhaust valve opening timing (first exhaust valve opening timing EVO1). Since the pressure in the combustion chamber near the expansion bottom dead center BDC becomes higher, the pressure in the combustion chamber becomes higher even after the exhaust stroke starts. Therefore, the work is reduced by the portion indicated by the region S1.

  Therefore, when the engine 10 is operated in the operation region 1, the present control device adjusts the opening degree of the wastegate valve 54 so that the actual turbine passing gas flow rate matches the gas flow rate threshold value.

  As a result, when the engine 10 is operated in the operation region 1, the exhaust gas pressure decreases because the turbine passing gas flow rate does not become excessive. Therefore, exhaust loss is reduced. That is, according to the present control device, as indicated by the solid line L2 in FIG. 2, the pressure in the combustion chamber after the exhaust valve is opened is lowered. As a result, the work loss of the portion indicated by the region S1 is avoided. Further, the turbine rotation speed is maintained at “the rotation speed at which supercharging can be performed with good response to the acceleration request”. Therefore, the turbo lag does not become long. From the above, the present control device can operate the engine efficiently without sacrificing the acceleration performance of the engine.

(Operation area 2)
When the engine 10 is operated in the operation region 2, even if the wastegate valve 54 is closed, the turbine passing gas flow rate becomes smaller than the gas flow rate threshold (see the curve C1). Accordingly, when the waste gate valve 54 is opened, the turbine passing gas flow rate is excessively decreased, and the turbine rotational speed is excessively decreased. Therefore, it is not preferable to open the waste gate valve 54.

  However, even in the operation region 2, there is a region where the exhaust pressure is high at the exhaust valve opening timing, and also in this case, the exhaust loss increases. Therefore, in such a region, the exhaust valve opening timing is advanced from the first exhaust valve opening timing EVO1 to the second exhaust valve opening timing EVO2. That is, the exhaust valve opening timing is advanced from the expansion bottom dead center BDC toward the compression top dead center TDC.

  The effect of this will be described with reference to “FIG. 3 which is a PV diagram similar to FIG. 2”. When the engine 10 is operated in the operation region 1, the exhaust valve opening timing is the expansion bottom dead center. The first exhaust valve opening timing EVO1 in the vicinity of BDC is set. On the other hand, when the engine 10 is operated in the operation region 2, the exhaust valve opening timing is set to the second exhaust valve opening timing EVO2. As a result, in the latter half of the expansion stroke, the pressure in the combustion chamber starts to drop early, so that the work is reduced by the amount indicated by the area S2. On the other hand, after the expansion bottom dead center BDC, the pressure in the combustion chamber is reduced, so that the exhaust loss is reduced and the work is substantially increased by the amount indicated by the area S3.

  In other words, the control device sets the second exhaust valve opening timing EVO2 to “a timing when the area S3 becomes larger than the area S2”. That is, the second exhaust valve opening timing EVO2 is “the work increase S3 caused by the decrease in the pressure in the combustion chamber in the exhaust stroke rather than the work decrease S2 caused by the decrease in the pressure in the combustion chamber in the expansion stroke”. Is set to “when the value increases”. As a result, the work increases by an amount obtained by subtracting the area S2 from the area S3 (S3-S2). Therefore, the present control device can operate the engine more efficiently.

(Operation area 3)
Since the operation region 3 belongs to the second operation region, when the engine 10 is operated in the operation region 3, the exhaust valve opening timing is changed from the first exhaust valve opening timing EVO1 to the second exhaust valve opening timing. It may be accelerated to EVO2. However, when the engine 10 is operated in the operation region 3, the intake air flow rate is relatively small, and therefore the turbine passing gas flow rate is also small. For this reason, even if the exhaust valve opening timing is set to the first exhaust valve opening timing EVO1, the exhaust loss (area S3 in FIG. 3) does not become so large. On the contrary, if the exhaust valve opening timing is set to the second exhaust valve opening timing EVO2, the expansion ratio is decreased, and the work loss (area S2 in FIG. 3) may be increased. Therefore, when the engine 10 is operated in the operation region 3, the present control device closes the waste gate valve 54 and sets the exhaust valve opening timing to the first exhaust valve opening timing EVO1 (expansion bottom dead center BDC or expansion). Set near the bottom dead center). The above is the outline of the exhaust loss reduction control of the present control device.

<Actual operation of this controller>
First, the operation of the present control device will be described from the case where the engine 10 is in the operating state (low load and low rotational speed) indicated by the point A in FIG. The CPU 71 of the electric control device 70 repeatedly executes the fuel injection control routine shown in FIG. 6 every time the crank angle of each cylinder coincides with a predetermined crank angle before the intake top dead center (for example, BTDC 90 °). ing. Hereinafter, a cylinder whose crank angle coincides with the predetermined crank angle before the intake top dead center is also referred to as a “fuel injection cylinder”.

  Accordingly, when the crank angle of any cylinder coincides with the predetermined crank angle, the CPU 71 proceeds from step 600 to step 605 and sets the target air-fuel ratio Abfref to the stoichiometric air-fuel ratio Stoich.

  Next, the CPU 71 proceeds to step 610 to acquire the in-cylinder intake air amount Mc. The in-cylinder intake air amount Mc is the amount of air that flows into the fuel injection cylinder during the current intake stroke of the fuel injection cylinder. The in-cylinder intake air amount Mc is determined based on the mass flow rate GA acquired from the hot-wire air flow meter 62 and the engine rotational speed NE.

  Next, the CPU 71 proceeds to step 615 to acquire the fuel injection amount Fi by dividing the cylinder intake air amount Mc by the target air-fuel ratio Abfref. The target air-fuel ratio Abfref at this time is set to the stoichiometric air-fuel ratio Stoich by the processing of step 605 in FIG. Accordingly, the fuel injection amount Fi is a fuel injection amount for making the air-fuel ratio of the air-fuel mixture supplied to the fuel injection cylinder coincide with the stoichiometric air-fuel ratio Stoch.

  Next, the CPU 71 proceeds to step 620 and issues a valve opening instruction to the injector 39 so that fuel is injected from the injector 39 provided for the fuel injection cylinder by the fuel injection amount Fi. Next, the CPU 71 proceeds to step 695 to end the present routine tentatively.

  By the way, the CPU 71 repeatedly performs the “exhaust loss reduction control flag setting routine (flag setting routine)” shown in FIG. 7 every elapse of a predetermined time. Therefore, when the predetermined timing comes, the CPU 71 starts processing from step 700 and proceeds to step 705.

  In step 705, the CPU 71 sets an exhaust loss reduction control flag XL. The value of the exhaust loss reduction control flag XL is determined based on the operating state P determined by the “load factor KL and engine speed NE” of the engine 10 at the present time in any of the operating regions shown in step 705 of FIGS. It is determined based on whether it belongs to the operating region. That is, when the operation state P is within the operation region 1, the exhaust loss reduction control flag XL is “1”, when the operation state P is within the operation region 2, the exhaust loss reduction control flag XL is “2”, and when the operation state P is within the operation region 3. The exhaust loss reduction control flag XL is set to “3”.

Here, the load factor KL is obtained by the following equation (1). Instead of the load factor KL, an accelerator pedal operation amount Accp may be used. In the equation (1), Mc is the in-cylinder intake air amount, ρ is the air density (unit is (g / l)), L is the exhaust amount of the engine 10 (unit is (l)), and “4” is the engine. The number of cylinders is 10.
KL = (Mc / (ρ · L / 4)) · 100% (1)

  At present, the engine 10 is in the operating state indicated by point A in FIG. Accordingly, the CPU 71 sets the exhaust loss reduction control flag XL to “3” in step 705, proceeds to step 795, and once ends this routine.

  Further, the CPU 71 repeats the “exhaust valve opening timing control routine” shown in FIG. 8 every elapse of a predetermined time. Therefore, when the predetermined timing is reached, the CPU 71 starts processing from step 800 and proceeds to step 805.

  In step 805, the CPU 71 determines whether or not the exhaust loss reduction control flag XL is “2”. At present, the exhaust loss reduction control flag XL is set to “3” in step 705 of FIG. Accordingly, the CPU 71 makes a “No” determination at step 805 to proceed to step 820.

  In step 820, the CPU 71 sets the target exhaust valve opening timing EVOtgt to “0”. When the target exhaust valve opening timing EVOtgt is set to “0”, the opening timing of the exhaust valve 35 is controlled to be the expansion bottom dead center BDC (or the timing near the expansion bottom dead center BDC). Next, the CPU 71 proceeds to step 815 to give an instruction to the exhaust valve control device 36 so that the exhaust valve opening timing becomes the target exhaust valve opening timing EVOtgt. Therefore, the valve opening timing of the exhaust valve 35 is controlled so as to become the expansion bottom dead center BDC. Next, the CPU 71 proceeds to step 895 to end the present routine tentatively. The exhaust valve opening timing at this time is also referred to as “first exhaust valve opening timing EVO1” for convenience.

  In addition, the CPU 71 repeats the “WGV opening degree control routine” shown in FIG. 9 every elapse of a predetermined time. Therefore, when the predetermined timing is reached, the CPU 71 starts processing from step 900 and proceeds to step 905.

  In step 905, the CPU 71 determines whether or not the exhaust loss reduction control flag XL is “1”. At present, the exhaust loss reduction control flag XL is set to “3” in step 705 of FIG. Accordingly, the CPU 71 makes a “No” determination at step 905 to proceed to step 910.

  In step 910, the CPU 71 sets the target wastegate valve opening WGVtgt to “0”. When the target wastegate valve opening degree WGVtgt is set to “0”, the wastegate valve 54 is controlled to be fully closed (the turbine bypass passage 55 is completely closed). Next, the CPU 71 proceeds to step 915 and gives an instruction to the wastegate valve actuator 54a so that the actual opening (WGV opening) of the wastegate valve 54 becomes the target wastegate valve opening WGVtgt. Accordingly, the waste gate valve 54 is fully closed. Next, the CPU 71 proceeds to step 995 to end the present routine tentatively.

  As described above, when the engine 10 is in the operation state (low load and low rotational speed) indicated by the point A in FIG. 5, the waste gate valve 54 is closed (fully closed) and the exhaust valve 35 is opened. The timing is set to the expansion bottom dead center BDC (first exhaust valve opening timing EVO1). That is, exhaust loss control is not performed (see time t0 in FIG. 10).

  Next, the case where the operation of the engine 10 is continued, the load factor KL and the engine speed NE are increased, and the operation state of the engine 10 is shifted from the operation region 3 to the operation region 2 (see state B in FIG. 5). To do.

  Even in this case, the CPU 71 performs processing of each step of FIG. Therefore, the CPU 71 injects fuel so that the air-fuel ratio of the air-fuel mixture supplied to the engine matches the stoichiometric air-fuel ratio.

  Furthermore, the present time is immediately after the operation state of the engine 10 becomes the state B in FIG. 5 (the state in the operation region 2). Accordingly, when the CPU 71 starts processing from step 700 in FIG. 7 and proceeds to step 705, the value of the “exhaust loss reduction control flag XL” is set to “2” in step 705.

  In addition, when the CPU 71 proceeds to step 805 following step 800 in FIG. 8, it determines “Yes” at step 805. Then, the CPU proceeds to step 810 to set the target exhaust valve opening timing EVOtgt according to “the valve opening timing table (map) shown in step 810 of FIG. 8”.

  This valve opening timing table defines the relationship between “target exhaust valve opening timing EVOtgt” and “load factor KL and engine rotational speed NE”. The larger the load factor KL, the higher the pressure in the combustion chamber at a predetermined exhaust valve opening timing (the longer it takes to scavenge the air in the combustion chamber). Therefore, according to this valve opening timing table, the target exhaust valve opening timing EVOtgt is advanced as the load factor KL increases. Furthermore, since the intake air flow rate increases as the engine speed NE increases, the pressure in the combustion chamber at a predetermined exhaust valve opening timing increases (the time required to scavenge the air in the combustion chamber also increases). . Therefore, according to this valve opening timing table, the target exhaust valve opening timing EVOtgt is advanced as the engine speed NE increases. The target exhaust valve opening timing EVOtgt determined in this way is also referred to as “second exhaust valve opening timing EVO2” for convenience. As described above, the second exhaust valve opening timing EVO2 is determined by this valve opening timing table so that the area S3 shown in FIG. 3 is larger than the area S2 shown in FIG. Is done.

  Next, the CPU 71 proceeds to step 815 to give an instruction to the exhaust valve control device 36 so that the exhaust valve opening timing becomes the target exhaust valve opening timing EVOtgt. Accordingly, the valve opening timing of the exhaust valve 35 is controlled to be the second exhaust valve opening timing EVO2. As a result, the work increases by “the amount obtained by subtracting the area S2 from the area S3 (S3−S2)” shown in FIG.

  In addition, when the CPU 71 starts the process from step 900 of FIG. 9 and proceeds to step 905, the exhaust loss reduction control flag XL at the present time is “2”. judge. Then, the CPU performs the processing of step 910 and step 915 described above, and once ends this routine in step 995.

  As a result, the waste gate valve 54 is fully closed. Accordingly, exhaust loss is not reduced by waste gate valve opening control. As a result, since the turbine passing gas flow rate becomes equal to the intake air flow rate, the rotational speed of the turbine 46b is maximized in this operating state.

  As described above, in the operation region 2, the waste gate valve 54 is kept fully closed, and the opening timing of the exhaust valve 35 is advanced from the expansion bottom dead center BDC. As a result, exhaust loss is reduced (see times t1 to t2 in FIG. 10).

  Next, when the operation of the engine 10 is continued and the load factor KL and / or the engine rotational speed NE is increased, the operation state of the engine 10 is shifted from the operation region 2 to the operation region 1 (see state C in FIG. 5). Will be described.

  Even in this case, the CPU 71 performs processing of each step of FIG. Therefore, the CPU 71 injects fuel so that the air-fuel ratio of the air-fuel mixture supplied to the engine matches the stoichiometric air-fuel ratio.

  Furthermore, the present time is immediately after the operating state of the engine 10 becomes the state C in FIG. 5 (a state in the operating region 1). Therefore, when the CPU 71 starts processing from step 700 in FIG. 7 and proceeds to step 705, the value of the “exhaust loss reduction control flag XL” is set to “1” in step 705.

  In addition, when the CPU 71 proceeds to step 805 following step 800 in FIG. 8, the CPU 71 determines “No” in step 805 and executes the processes of step 820 and step 815 described above. As a result, the opening timing of the exhaust valve 35 is set to the expansion bottom dead center BDC (first exhaust valve opening timing EVO1). Therefore, exhaust loss reduction control by exhaust valve opening timing control is not performed.

  In addition, when the CPU 71 starts the process from step 900 of FIG. 9 and proceeds to step 905, the exhaust loss reduction control flag XL at the present time is “1”, so “Yes” is returned in step 905. judge.

  Then, the CPU 71 proceeds to step 920 and sets the target wastegate valve opening WGVtgt according to the “WGV opening table (map) shown in step 920 of FIG. 9”.

  This WGV opening table defines the relationship between “target waste gate valve opening WGVtgt” and “load factor KL and engine speed NE”.

  Since the intake air flow rate increases as the load factor KL increases, the exhaust pressure when the wastegate valve 54 is at a predetermined opening increases as the load factor KL increases. Therefore, the larger the load factor KL, the higher the pressure in the combustion chamber immediately after the exhaust valve is opened. Therefore, according to this WGV opening degree table, the target wastegate valve opening degree WGVtgt is increased as the load factor KL is increased, and the turbine passing gas flow rate is maintained at the gas flow rate threshold (the flow rate of the curve C1) described above.

  Furthermore, since the intake air flow rate increases as the engine speed NE increases, the exhaust pressure when the wastegate valve 54 is at a predetermined opening increases as the engine speed NE increases. Therefore, the higher the engine speed NE, the higher the pressure in the combustion chamber immediately after the exhaust valve is opened. Therefore, according to the WGV opening degree table, the target wastegate valve opening degree WGVtgt is increased as the engine speed NE is increased, and the turbine gas flow rate is maintained at the gas flow rate threshold value (the flow rate of the curve C1) described above. .

  Thereafter, the CPU performs the process of step 915 and once ends the routine at step 995. Thereby, the waste gate valve opening degree WGV is matched with the target waste gate valve opening degree WGVtgt. Accordingly, a part of the exhaust gas in the exhaust passage bypasses the turbine 46b (passes through the turbine bypass passage 55) and is discharged to the outside. As a result, the exhaust pressure is reduced, exhaust loss is reduced, and work loss in the portion indicated by the region S1 in FIG. 2 is avoided.

  As described above, when the load factor KL and the engine rotational speed NE are increased and the intake air flow rate exceeds the curve C1 in FIG. 5 and the operation state is in the operation region 1, the exhaust valve opening timing is the first exhaust valve opening time. The waste gate valve opening degree WGV is adjusted so that the time EVO1 is set and “the turbine passing gas flow rate becomes the gas flow rate threshold value”. Therefore, the exhaust loss of the engine 10 can be reduced, and the rotational speed of the turbine 46b can be maintained at a sufficient speed (see times t2 to t3 in FIG. 10).

  Next, when the operation of the engine 10 is continued and the load factor KL is decreased, the engine speed NE is increased, and the operation state of the engine 10 is shifted from the operation region 1 to the operation region 3 (see the state D in FIG. 5). .).

  Even in this case, the CPU 71 performs processing of each step of FIG. Therefore, the CPU 71 injects fuel so that the air-fuel ratio of the air-fuel mixture supplied to the engine matches the stoichiometric air-fuel ratio.

  Furthermore, the present time is immediately after the operating state of the engine 10 becomes the state D in FIG. 5 (the state in the operating region 3). Therefore, when the CPU 71 starts processing from step 700 of FIG. 7 and proceeds to step 705, the value of the “exhaust loss reduction control flag XL” is set to “3” in step 705.

  In addition, when the CPU 71 proceeds to step 805 following step 800 in FIG. 8, the CPU 71 determines “No” in step 805 and executes the processes of step 820 and step 815 described above. As a result, the opening timing of the exhaust valve 35 is set to the expansion bottom dead center BDC (first exhaust valve opening timing EVO1). Therefore, exhaust loss reduction control by exhaust valve opening timing control is not performed.

  In addition, when the CPU 71 starts the process from step 900 of FIG. 9 and proceeds to step 905, the exhaust loss reduction control flag XL at the present time is “3”. judge.

  Then, the CPU 71 proceeds to step 910 to set the target wastegate valve opening WGVtgt according to “0”. As a result, the waste gate valve 54 is fully closed. Accordingly, exhaust loss is not reduced by waste gate valve opening control.

  As described above, when the load factor KL decreases, while the engine speed NE increases and the intake air flow rate exceeds the curve C1 in FIG. And the opening timing of the exhaust valve 35 is set to the expansion bottom dead center BDC (first exhaust valve opening timing EVO1). That is, the operation region 3 is a low intake air flow rate region in which the exhaust pressure does not cause a large exhaust loss. Therefore, exhaust loss control is not performed. (See after time t3 in FIG. 10).

  As described above, the control device for an internal combustion engine according to the present invention includes a supercharger including a supercharger (46), a wastegate valve (54), and a wastegate valve drive mechanism (54a). Applies to internal combustion engines.

  The supercharger (46) includes a turbine (46b) disposed in an exhaust pipe (52) forming an “exhaust passage communicating with a combustion chamber (25) of an internal combustion engine” and an “intake air communicating with the combustion chamber”. And a compressor (46a) disposed in the intake pipe (42) forming a "passage". The compressor (46a) rotates integrally with the turbine (46b).

  The waste gate valve (54) is interposed in a bypass passage (55) that bypasses the turbine (46b). One end of the bypass passage (55) is connected (communication) to “the upstream position of the exhaust pipe (52) from the turbine (46b)”. The other end of the bypass passage (55) is connected (communication) to a “position downstream of the turbine (46b) of the exhaust pipe (52)”.

  The waste gate valve drive mechanism (54a) changes the opening degree of the waste gate valve (54) in accordance with an instruction (see step 915 in FIG. 9). Thereby, the said wastegate valve drive mechanism (54a) changes the flow-path cross-sectional area of the said bypass channel (55).

  Furthermore, this control device is characterized by comprising waste gate valve opening control means (see steps 910, 915 and 920 in FIG. 9).

  The waste gate valve opening control means is operated when the engine is operated in a first operating region where the intake air flow rate of the engine is equal to or greater than a predetermined gas flow rate threshold (the first operating region of FIG. 1 and the operation of FIG. 5). (Refer to region 1), “for controlling the opening degree of the waste gate valve (54) so that the turbine passing gas flow rate, which is the flow rate of the exhaust gas passing through the turbine (46b), becomes the same gas flow rate threshold value”. An instruction is given to the wastegate valve driving mechanism (54a) (see step 920 and step 915 in FIG. 9). As a result, the waste gate valve (54) is opened so that the actual gas flow rate through the turbine becomes the gas flow rate threshold value.

  Further, the waste gate valve opening control means is operated when the engine is operated in a second operation region where the intake air flow rate of the engine is smaller than the gas flow rate threshold (second operation region of FIG. 1, FIG. 5). The operation area 2 is referred to), and an instruction for “the wastegate valve (54) closes the bypass passage (55)” (an instruction to set the wastegate valve opening to 0) is sent to the wastegate valve drive mechanism ( 54a) (see step 910 and step 915 in FIG. 9).

  As a result, the present control device can maintain the turbine rotational speed at an appropriate value, and therefore can reduce the exhaust pressure without sacrificing the acceleration performance of the engine, so that the engine can be operated efficiently.

  In this case, it is desirable that the present control device includes an exhaust valve opening timing change mechanism (36) and an exhaust valve opening timing control means (see steps 810, 815 and 820 in FIG. 8).

  The exhaust valve opening timing changing mechanism (36) changes the opening timing of the exhaust valve (35) of the engine in accordance with an instruction (see step 815 in FIG. 8).

  The exhaust valve opening timing control means (see steps 810, 815 and 820 in FIG. 8) is operated when the engine is operated in the first operating region (the first operating region in FIG. 1, the operation in FIG. 5). (Refer to region 1), and an instruction for setting the exhaust valve opening timing to the first exhaust valve opening timing in the vicinity of the expansion bottom dead center is given to the exhaust valve opening timing changing mechanism (36). (See step 820 in FIG. 8).

  Further, the exhaust valve opening timing control means is configured to open the exhaust valve when the engine is operated in the second operation region (see the second operation region in FIG. 1 and the operation region 2 in FIG. 5). The exhaust valve opening timing changing mechanism (36) is instructed to set the timing to the second exhaust valve opening timing that is more advanced than the first exhaust valve opening timing ( (See step 810 in FIG. 8.)

  As a result, the exhaust valve opening timing is such that the increase in work caused by the decrease in the pressure in the combustion chamber during the exhaust stroke is greater than the decrease in work caused by the decrease in the pressure in the combustion chamber during the expansion stroke. , Is set. Therefore, the present control device can operate the engine more efficiently.

  The present invention is not limited to the above-described embodiment, and various modifications can be employed within the scope of the present invention. For example, in the above embodiment, the injector 39 is a port injection valve that injects fuel into the intake port, but may be a cylinder injection valve that injects fuel directly into the combustion chamber 25. By directly injecting fuel into the combustion chamber 25, the engine 10 can be operated at an air-fuel ratio (lean air-fuel ratio) larger than the stoichiometric air-fuel ratio. As a result, the engine 10 can be operated with a lean air-fuel ratio, and fuel consumption can be suppressed.

Further, in the operation region 3 in FIG. 5, the exhaust valve opening timing is set to the first exhaust valve opening timing EVO1, but it may be set to the second exhaust valve opening timing EVO2. Furthermore, the waste gate valve actuator 54a may be a known diaphragm actuator that drives the waste gate valve 54 by adjusting the pressure applied to the diaphragm. At this time, the electric control device 70 is configured to adjust the opening degree of the wastegate valve 54 by adjusting the pressure applied to the diaphragm.

It is the figure which showed the driving | operation area | region used in the control performed by the control apparatus of the internal combustion engine of this invention. It is the PV diagram which showed the exhaust loss reduction effect by the wastegate valve opening degree control which concerns on embodiment of this invention. It is a PV diagram which showed the exhaust loss reduction effect by the exhaust valve opening timing control concerning the embodiment of the present invention. 1 is a schematic diagram of an internal combustion engine to which a control device for an internal combustion engine according to an embodiment of the present invention is applied. It is the figure which showed the driving | operation area | region which CPU of embodiment of this invention refers to It is the flowchart which showed the fuel-injection control routine which CPU of embodiment of this invention performs. It is the flowchart which showed the exhaust loss reduction control flag setting routine which CPU of embodiment of this invention performs. It is the flowchart which showed the exhaust valve opening timing control routine which CPU of embodiment of this invention performs. It is the flowchart which showed the WGV opening degree control routine which CPU of embodiment of this invention performs. 4 is a time chart showing temporal changes in engine speed, load factor, intake air flow rate, exhaust valve opening timing, exhaust loss reduction control flag, and wastegate valve opening in the embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 20 ... Cylinder block part, 25 ... Combustion chamber, 30 ... Cylinder head part, 31 ... Intake port, 32 ... Intake valve, 33 ... Intake valve control apparatus, 34 ... Exhaust port, 35 ... Exhaust valve, 36 ... Exhaust valve control device, 40 ... intake system, 42 ... intake pipe, 44 ... throttle valve, 44a ... throttle valve actuator, 46 ... supercharger, 46a ... compressor, 46b ... turbine, 46c ... rotating shaft, 47 ... compressor bypass passage 48 ... Air bypass valve, 50 ... Exhaust system, 52 ... Exhaust pipe, 54 ... Waste gate valve, 54a ... Waste gate valve actuator, 55 ... Turbine bypass passage.

Claims (2)

A turbine disposed in an exhaust pipe forming an exhaust passage communicating with a combustion chamber of an internal combustion engine, a compressor disposed in an intake pipe forming an intake passage communicating with the combustion chamber, and rotating integrally with the turbine; A supercharger having
A wastegate interposed in a bypass passage that bypasses the turbine by connecting one end of the exhaust pipe upstream of the turbine and the other end of the exhaust pipe downstream of the turbine. A valve,
A wastegate valve drive mechanism that changes the flow passage cross-sectional area of the bypass passage by changing the opening of the wastegate valve in accordance with an instruction;
A control device for an internal combustion engine with a supercharger comprising:
When the engine is operated in a first operation region where the intake air flow rate of the engine is equal to or higher than a predetermined gas flow rate threshold value, the turbine passing gas flow rate, which is the flow rate of exhaust gas passing through the turbine, becomes the same gas flow rate threshold value. When the engine is operated in the second operation region where the intake air flow rate of the engine is smaller than the gas flow rate threshold value, the waste gate valve is controlled by the bypass passage. And a wastegate valve opening control means for giving an instruction to the wastegate valve drive mechanism so as to be closed. The control apparatus for an internal combustion engine with a supercharger according to claim 1, further comprising:
An exhaust valve opening timing changing mechanism for changing the opening timing of the exhaust valve of the engine according to the instruction;
When the engine is operated in the first operating region, the exhaust valve opening timing is set to the first exhaust valve opening timing in the vicinity of the expansion bottom dead center, and the engine is operated in the second operating region. In this case, the exhaust valve opening timing changing mechanism is instructed to set the exhaust valve opening timing to the second exhaust valve opening timing that is more advanced than the first exhaust valve opening timing. An exhaust valve opening timing control means to provide,
A control device comprising:

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