JP2012188994A - Control apparatus for internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily suppress an exhaust purification catalyst from being overheated when gas blows out via a combustor chamber from an inlet system toward an exhaust system, or an exhaust gas recirculation passage, regarding a control apparatus for an internal combustion engine with a supercharger including an exhaust bypass passage for bypassing a turbine of a turbosupercharger and a wastegate valve for opening and closing the exhaust bypass passage.SOLUTION: The control apparatus includes: the turbo supercharger 20 including the turbine 20b that is actuated by an exhaust energy in the exhaust passage 14; the exhaust bypass passage 32 for bypassing the turbine 20b; and the WGV 34 that can switch on-off of the exhaust bypass passage 32. The control apparatus prohibits the opening of the WGV 34 when it is determined that gas blow-out occurs via the combustor chamber from the inlet system toward the exhaust system or the exhaust gas recirculation passage.

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger, and in particular, controls an internal combustion engine including an exhaust bypass passage that bypasses a turbine of a turbocharger and a waste gate valve that opens and closes the exhaust bypass passage. The present invention also relates to a control device for a supercharger-equipped internal combustion engine.

  Conventionally, for example, Patent Document 1 discloses a control device for an internal combustion engine with a turbocharger. In this conventional control device, when the valve overlap amount is reduced during deceleration from the supercharging state, if the oxygen sensor signal indicates a rich output, the exhaust VVT retard angle is controlled after the intake VVT advance amount is controlled. When the oxygen sensor signal indicates a lean output, the intake VVT advance amount is controlled after the exhaust VVT retard amount is controlled.

JP 2009-19611 A Japanese Patent Laid-Open No. 11-229915

  As in the configuration described in Patent Document 1, an internal combustion engine including an exhaust bypass passage that bypasses the turbine of the turbocharger and a waste gate valve that opens and closes the exhaust bypass passage is known. In such an internal combustion engine, when the intake pressure is higher than the exhaust pressure upstream of the turbine in the low rotation and high load region, a valve overlap amount is provided, or an exhaust gas recirculation valve (EGR valve) is opened. Otherwise, a blow-through of gas (fresh air mixed with fuel or fresh air) occurs through the combustion chamber or the exhaust gas recirculation passage (EGR passage) from the intake system to the exhaust system. .

  If the waste gate valve is opened at the time of occurrence of the gas blow-through as described above, a part of the blown-through gas flows directly into the exhaust purification catalyst via the exhaust bypass passage without going through the turbine. Here, when the exhaust gas passes through the turbine, exhaust energy is consumed by work in the turbine. For this reason, the temperature of the exhaust gas passing through the exhaust bypass passage is higher than the temperature of the exhaust gas passing through the turbine. Therefore, the temperature of the exhaust gas flowing into the exhaust purification catalyst becomes higher when the waste gate valve is open than when it is closed, and the temperature of the exhaust purification catalyst becomes higher. Therefore, if the waste gate valve is opened at the time of occurrence of the gas blow-off as described above, a part of the blow-by gas is directly connected to the exhaust purification catalyst via the exhaust bypass passage under a situation where the exhaust purification catalyst becomes high temperature. Will flow into. As a result, the blow-by gas may react in the high temperature exhaust purification catalyst, and the exhaust purification catalyst may overheat.

  The present invention has been made in order to solve the above-described problems, and includes an exhaust bypass passage that bypasses the turbine of the turbocharger and a wastegate valve that opens and closes the exhaust bypass passage. Provided is a control device for an internal combustion engine with a supercharger capable of satisfactorily suppressing overheating of an exhaust purification catalyst when gas blow-through occurs from a combustion system to an exhaust system through a combustion chamber or an exhaust gas recirculation passage With the goal.

1st invention is a control apparatus of the internal combustion engine with a supercharger,
A turbocharger having a turbine operating by exhaust energy in the exhaust passage;
An exhaust bypass passage that branches off from the exhaust passage at a portion upstream of the turbine and merges with the exhaust passage at a portion downstream of the turbine;
A waste gate valve capable of switching opening and closing of the exhaust bypass passage;
An exhaust purification catalyst for purifying exhaust gas, disposed in the exhaust passage downstream of the downstream portion;
A gas blow-by determination means for determining whether or not gas blow-through has occurred through the combustion chamber or the exhaust gas recirculation passage from the intake system to the exhaust system;
Waste gate opening prohibiting means for prohibiting valve opening of the waste gate valve when it is determined by the gas blow-through determining means that the gas blow-through occurs;
It is characterized by providing.

The second invention is the first invention, wherein
An overlap amount adjusting mechanism for adjusting a valve overlap amount between the intake valve opening period and the exhaust valve opening period;
An operation region transition determination unit that determines whether or not a transition of the operation region from the region determined to cause the gas blow-by by the gas blow-out determination unit to be performed is performed;
When the transition of the operation region is performed, the deceleration overlap amount reduction means for reducing the valve overlap amount;
When the shift of the operation region is performed, the deceleration waste gate opening prohibiting means for prohibiting the valve opening of the waste gate valve until the valve overlap amount is reduced by the deceleration valve overlap amount reducing means;
Is further provided.

The third invention is the first or second invention, wherein
A catalyst temperature acquisition means for acquiring the temperature of the exhaust purification catalyst;
The waste gate opening prohibiting unit prohibits the opening of the waste gate valve when the temperature of the exhaust purification catalyst is equal to or higher than a predetermined temperature.

  According to the first aspect of the present invention, when gas blow-through occurs from the intake system to the exhaust system through the combustion chamber or the exhaust gas recirculation passage, the blow-by gas does not pass through the turbine and the exhaust purification catalyst. It is possible to suppress direct inflow into Thereby, it can suppress favorably that an exhaust purification catalyst overheats.

  According to the second invention, by reducing the valve overlap amount before opening the waste gate valve, the gas blown from the intake system to the exhaust system passes through the exhaust bypass passage without passing through the turbine, and is in a high temperature state. It is possible to prevent the exhaust gas from directly flowing into the exhaust purification catalyst. For this reason, overheating of the exhaust purification catalyst can be suppressed.

  According to the third aspect of the invention, the control for prohibiting the opening of the waste gate valve when the gas is blown out is executed only in a situation where the temperature of the exhaust purification catalyst is equal to or higher than the predetermined temperature. Accordingly, when the waste gate valve is set to open / close in accordance with the supercharging pressure, it is possible to prevent overheating of the exhaust purification catalyst without hindering the implementation of control based on such setting as much as possible. .

It is a figure for demonstrating the system configuration | structure of the internal combustion engine of Embodiment 1 of this invention. It is a figure showing the relationship between a scavenge area | region and an intercept point. It is a figure for demonstrating operation | movement when the characteristic WGV control in Embodiment 1 of this invention is performed compared with the operation | movement when the said WGV control is not performed. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a figure showing the change of the driving | operation area | region (here, prescribed | regulated by the load factor KL and engine speed NE) at the time of deceleration from a scavenge area | region. It is a figure for demonstrating the characteristic control of the valve overlap amount and WGV in Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 2 of this invention.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a system configuration of an internal combustion engine 10 according to Embodiment 1 of the present invention. The system of the present embodiment includes an internal combustion engine (here, a spark ignition gasoline engine is taken as an example) 10. An intake passage 12 and an exhaust passage 14 communicate with each cylinder of the internal combustion engine 10.

  An air cleaner 16 is attached in the vicinity of the inlet of the intake passage 12. An air flow meter 18 that outputs a signal corresponding to the flow rate of air taken into the intake passage 12 is provided in the vicinity of the downstream side of the air cleaner 16. A compressor 20 a of the turbocharger 20 is installed downstream of the air flow meter 18. The compressor 20a is integrally connected to a turbine 20b disposed in the exhaust passage 14 via a connecting shaft.

  An intercooler 22 that cools the compressed air is provided downstream of the compressor 20a. An electronically controlled throttle valve 24 is provided downstream of the intercooler 22. An intake pressure sensor 26 for detecting intake pressure (supercharging pressure) is disposed downstream of the throttle valve 24. A fuel injection valve 28 for injecting fuel into the intake port is provided for each cylinder of the internal combustion engine 10. Further, each cylinder of the internal combustion engine 10 is provided with a spark plug 30 for igniting the air-fuel mixture.

  Connected to the exhaust passage 14 is an exhaust bypass passage 32 that is branched from the exhaust passage 14 at a location upstream of the turbine 20b and merges with the exhaust passage 14 at a location downstream of the turbine 20b. Has been. A waste gate valve (WGV) 34 that can switch opening and closing of the exhaust bypass passage 32 is provided in the middle of the exhaust bypass passage 32. Here, it is assumed that the WGV 34 is configured to be adjustable to an arbitrary opening degree by a pressure-regulating or electric actuator (not shown). Further, an exhaust purification catalyst (hereinafter simply referred to as “catalyst”) 36 for purifying exhaust gas is provided in the exhaust passage 14 further downstream than the connection portion with the exhaust bypass passage 32 on the downstream side of the turbine 20b. Is arranged.

  The internal combustion engine 10 also includes an EGR (Exhaust Gas Recirculation) passage 38 that connects the intake passage 12 downstream of the throttle valve 24 and the exhaust passage 14 upstream of the turbine 20b. An EGR valve 40 that opens and closes the EGR passage 38 is provided near the connection port on the intake passage 12 side in the EGR passage 38. According to the EGR device having such a configuration, the EGR rate can be adjusted by changing the flow rate of the EGR gas flowing through the EGR passage 38 by changing the opening degree of the EGR valve 40.

  The internal combustion engine 10 also includes an intake variable valve mechanism 42 and an exhaust variable valve mechanism 44 for opening and closing an intake valve and an exhaust valve (not shown), respectively. Here, as an example, the variable valve mechanisms 42 and 44 can change the opening / closing timing of the intake valve and the exhaust valve by changing the rotation phase of the camshaft with respect to the rotation of the crankshaft (not shown). It has a (VVT) mechanism. Further, in the vicinity of the intake variable valve mechanism 42 and the exhaust variable valve mechanism 44, an intake cam angle sensor 46 and an exhaust cam angle sensor 48 for detecting advance amounts of opening / closing timings of the intake valve and the exhaust valve, respectively. Are provided.

  Further, the system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50. In addition to the air flow meter 18, the intake pressure sensor 26, and the cam angle sensors 46 and 48 described above, an operating state of the internal combustion engine 10 such as a crank angle sensor 52 for detecting the engine speed is detected at the input portion of the ECU 50. For this purpose, various sensors are connected. Further, an accelerator opening sensor 54 for detecting the amount of depression (accelerator opening) of an accelerator pedal mounted on a vehicle equipped with the internal combustion engine 10 is connected to the input portion of the ECU 50. Further, an output portion of the ECU 50 controls the operating state of the internal combustion engine 10 such as the throttle valve 24, the fuel injection valve 28, the spark plug 30, the WGV 34, the EGR valve 40, and the variable valve mechanisms 42 and 44 described above. Various actuators are connected. The ECU 50 controls the operating state of the internal combustion engine 10 by operating various actuators according to a predetermined program based on the outputs of the various sensors described above.

[Characteristic Control in Embodiment 1]
FIG. 2 is a diagram showing the relationship between the scavenge area and the intercept point.
According to the intake variable valve mechanism 42 and the exhaust variable valve mechanism 44 described above, the valve overlap amount between the exhaust valve opening period and the intake valve opening period can be adjusted. In the low rotation and high load region of the internal combustion engine 10, the intake pressure is higher than the back pressure (exhaust pressure upstream of the turbine 20b). Thus, if the valve overlap amount is set when the intake pressure is higher than the back pressure, the gas (port injection type fuel injection valve 28) from the intake system to the exhaust system via the combustion chamber is set. In the case where the unburned mixture of fresh air and fuel) is blown out. As a result, an effect of scavenging residual gas in the cylinder (scavenging effect) is produced. As shown in FIG. 2, the low rotation and high load region where such a scavenging effect occurs is referred to herein as a “scavenging region”.

  Further, the WGV 34 is generally set to open when the supercharging pressure reaches a predetermined set supercharging pressure at the time of high load from the viewpoint of engine protection. The “intercept point” shown in FIG. 2 is based on opening the WGV 34 at full load (when the throttle valve 24 is fully open) when the WGV 34 is set to open / close in accordance with the supercharging pressure. This is the engine speed at which supercharging pressure control (limitation) is started. A curve indicated by a solid line in FIG. 2 indicates a full load torque curve when the WGV 34 is set to be opened at the intercept point. In this case, since the WGV 34 is opened at the intercept point, an increase in the supercharging pressure corresponding to the increase in the engine speed (turbine speed) is suppressed. As shown in FIG. In the high speed region, the torque is constant with respect to the increase in engine speed.

  When the opening / closing control of the WGV 34 according to the supercharging pressure as shown in FIG. 2 is performed, the vicinity of the intercept point and the scavenging area overlap. As a result, there is an operating region that overlaps the scavenging region with the WGV 34 open, on the high rotation side of the intercept point, as in the region indicated by “Concern overheating of catalyst” in FIG. In such an operation region, part of the gas blown through the combustion chamber (hereinafter referred to as “scavenge gas”) flows directly into the catalyst 36 via the exhaust bypass passage 32 without passing through the turbine 20b. It becomes like this.

  Here, when the exhaust gas passes through the turbine 20b, exhaust energy is consumed by work in the turbine 20b. For this reason, the temperature of the exhaust gas passing through the exhaust bypass passage 32 is higher than the temperature of the exhaust gas passing through the turbine 20b. For this reason, the temperature of the exhaust gas flowing into the catalyst 36 becomes higher when the WGV 34 is open than when it is closed, and the temperature of the catalyst 36 becomes higher. Therefore, if the WGV 34 is opened when the gas blow-out occurs as described above, the scavenge gas (fresh air mixed with fuel) is directly passed through the exhaust bypass passage 32 under a situation where the catalyst 36 is at a high temperature. It will flow into the catalyst 36. As a result, the blow-by gas may react in the high-temperature catalyst 36 and the catalyst 36 may be overheated.

  Therefore, in the present embodiment, when the gas blowout occurs during the operation of the internal combustion engine 10 (that is, when the operation region corresponds to the scavenge region), the WGV 34 prohibits the opening of the WGV 34. Control was done.

  FIG. 3 is a diagram for explaining an operation when the characteristic WGV control in the first embodiment of the present invention is executed in comparison with an operation when the WGV control is not performed. More specifically, a waveform indicated by a solid line in FIG. 3 is obtained when the WGV control of the present embodiment is executed, and a waveform indicated by a broken line in FIG. 3 is not subjected to the WGV control. (I.e., the general control that the WGV 34 opens when the intercept point is reached). The operation shown in FIG. 3 is, for example, during acceleration with the throttle valve 24 fully open.

  As shown in FIG. 3 (C), according to the WGV control (solid line) of the present embodiment, unlike the execution of the general control (broken line) that opens the WGV 34 at the intercept point, the scavenging area is being used. Even when the intercept point is reached, the opening of the WGV 34 is prohibited, and the WGV 34 is controlled to the closed side (fully closed). As a result, as shown in FIG. 3D, the supercharging pressure is used up to the upper limit value due to hardware limitations of the internal combustion engine 10 during the use of the scavenge region. Thereafter, the WGV 34 is opened after passing through the scavenge area.

  According to such WGV control (solid line), as shown in FIG. 3 (B), the WGV passage flow rate (exhaust bypass) is used during the use of the scavenge region, unlike the case of execution of the general control (broken line). The flow rate of exhaust gas and scavenge gas passing through the passage 32 can be reduced. As a result, as shown in FIG. 3A, the exhaust gas and scavenge gas directly flowing into the catalyst 36 without passing through the turbine 20b cause the catalyst 36 to overheat beyond a predetermined catalyst upper limit temperature. Can be prevented.

  FIG. 4 is a flowchart showing a control routine executed by the ECU 50 in order to realize the WGV control of the first embodiment described above. This routine is repeatedly executed every predetermined control cycle.

  In the routine shown in FIG. 4, it is first determined whether or not the current operating region of the internal combustion engine 10 is a scavenging region (step 100). Specifically, the ECU 50 defines a scavenging area in relation to the operating area of the internal combustion engine 10 (an area based on the torque TRQ (or load factor KL) and the engine speed NE) (as shown in FIG. 2). Memorizing the relationship). In this step 100, the current operating range is determined based on the current torque TRQ calculated based on the output of the air flow meter 18 and the current engine speed NE acquired using the output of the crank angle sensor 52. It is determined whether or not it is an area. The scavenging area determination method is not limited to the above-described one. For example, if the exhaust pressure sensor that detects the exhaust pressure is provided together with the intake pressure sensor 26 that detects the intake pressure, By comparing the sensor value, it is determined whether the intake pressure is higher than the exhaust pressure, and by determining whether the valve overlap amount is set, it is determined whether it falls within the scavenging area. You may make it determine.

  When it is determined in step 100 that the current operation region is a scavenging region, it is determined whether or not the temperature of the catalyst 36 is equal to or higher than a predetermined temperature (step 102). The predetermined temperature in this step 102 is used to determine whether or not the catalyst 36 is overheated when exhaust gas and scavenge gas directly flow into the catalyst 36 without passing through the turbine 20b. This is preset as the temperature threshold.

  If it is determined in step 102 that the temperature of the catalyst 36 is equal to or higher than the predetermined temperature, the opening of the WGV 34 is prohibited (regardless of whether the WGV 34 is opened or closed according to the supercharging pressure) (step 104). ).

  According to the routine shown in FIG. 4 described above, the exhaust gas and the scavenge gas can be prevented from flowing directly into the catalyst 36 without passing through the turbine 20b during the use of the scavenge region. Thereby, it can suppress that the catalyst 36 overheats exceeding predetermined catalyst upper limit temperature.

  Further, according to the above routine, the control for prohibiting the valve opening of the WGV 34 during use of the scavenge region is executed only in a situation where the temperature of the catalyst 36 is equal to or higher than the predetermined temperature. Thereby, it is possible to prevent overheating of the catalyst 36 without hindering the control of the normal WGV 34 according to the supercharging pressure as much as possible.

  By the way, in the above-described first embodiment, the valve overlap amount is set under the situation where the intake pressure is higher than the exhaust pressure (upstream of the turbine 20b), so that the combustion chamber passes through the combustion chamber. The WGV control has been described for a situation in which gas blow-through (in this case, scavenging) occurs from the intake system to the exhaust system. However, when the EGR valve 40 is opened under a situation where the intake pressure is higher than the exhaust pressure, the gas (in this case, fresh air) is blown through the EGR passage 38 from the intake system to the exhaust system. Will occur. Even when such a gas blow-through occurs through the EGR passage 38, if the WGV 34 is opened, the exhaust gas and the blow-through gas (fresh air) directly pass through the catalyst 36 without passing through the turbine 20b. As a result, the catalyst 36 may become overheated. Therefore, instead of determining the scavenge area in step 100, or in addition to determining the presence or absence of gas blow-through through the EGR passage 38, the opening of the WGV 34 may be prohibited.

  In the first embodiment described above, when the ECU 50 executes the process of step 100, the “gas blow-off determining means” in the first invention satisfies the determination of step 100. By executing the process 104, the “waste gate opening prohibiting means” in the first invention is realized.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
The system of the present embodiment can be realized by causing the ECU 50 to execute a routine shown in FIG. 7 described later instead of the routine shown in FIG. 4 using the hardware configuration shown in FIG.

[Characteristic control in the second embodiment]
FIG. 5 is a diagram showing a change in the operation region (here, defined by the load factor KL and the engine speed NE) when deceleration from the scavenge region is performed. And FIG. 6 is a figure for demonstrating the characteristic control in Embodiment 2 of this invention. It is assumed that “point A” and “point B” shown in FIG. 6 correspond to those shown in FIG.

  In the system of the internal combustion engine 10 shown in FIG. 1, as shown in FIG. 3C, the WGV 34 is operated during normal times (except when high output is requested) in a region other than the high load region where the WGV 34 is opened from the viewpoint of engine protection. Control is performed such that the engine is opened at a predetermined opening according to the state (more specifically, the engine speed NE and the load factor KL) and is closed when high output is required (so-called normal open control). It has become. According to such normal open control, it is possible to reduce exhaust loss due to a decrease in exhaust pressure by opening the WGV 34 in a normal state. Further, by opening the WGV 34 during normal operation, the throttle opening required for obtaining the same torque is increased as compared with when the valve is closed, so that pump loss can be reduced. For these reasons, the fuel efficiency of the internal combustion engine 10 can be improved.

  During the use of the scavenge region that exists in the high load region, the temperature of the exhaust gas is higher than when the operation region on the low load side is used, and as a result, the temperature of the catalyst 36 is also high. When deceleration from such a scavenge region is performed (that is, when the operation region shifts from point A in the scavenge region to point B on the low load side, for example, as shown in FIG. 5 as an example) When the WGV 34 is opened immediately in accordance with the normal open control, the scavenge gas blown from the intake system to the exhaust system directly passes through the exhaust bypass passage 32 without passing through the turbine 20b and directly to the high temperature catalyst 36. Will flow into. As a result, there is a concern that the temperature of the catalyst 36 will rise.

  Therefore, in the present embodiment, when a transition from the scavenge area (point A) to the low load area (point B) is performed (at the time of deceleration), first, as shown by a broken line in FIG. The variable valve mechanism 42, 44 is used to reduce the valve overlap amount to a predetermined value. Then, until the valve overlap period is reduced to the predetermined value, as shown in FIG. 6B, the WGV 34 is opened toward the predetermined opening degree in the low load region (point B) required at the time of deceleration. It was banned. As described above, in the present embodiment, in the low rotation speed region, the valve overlap amount is gradually increased as the load factor KL increases, and the WGV 34 is closed to ensure the supercharging pressure. The valve overlap amount at the time of deceleration and the control of the WGV 34 are set to be different from those at the time of acceleration.

  FIG. 7 is a flowchart showing a control routine executed by the ECU 50 in order to realize the control of the valve overlap amount and the WGV 34 according to the second embodiment described above. In FIG. 7, the same steps as those shown in FIG. 4 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 7, if it is determined in step 100 that the current operating region of the internal combustion engine 10 is a scavenging region, then whether or not the change amount ΔKL of the load factor KL is a negative value is determined. Determination is made (step 200). The load factor KL can be calculated based on the intake air amount acquired using the air flow meter 18 and the engine speed NE acquired using the crank angle sensor 52.

  When it is determined in step 200 that the change amount ΔKL of the load factor KL is a negative value, that is, when it can be determined that the operation region is shifted from the scavenging region to the low load side region, the valve Control for decreasing the overlap amount toward a predetermined value is executed (step 202). The predetermined value in this step 202 is assumed to be the valve overlap amount at the target point (point B in FIG. 5) in the current deceleration request. It should be noted that the control of the valve overlap amount in this step 202 may be performed so that the valve overlap amount is zero or substantially zero.

  Next, it is determined whether or not the valve overlap amount has reached the predetermined value (step 204). As a result, when it is determined that the valve overlap amount has reached the predetermined value, the WGV 34 is opened (step 206). In other words, it is permitted to open the WGV 34 toward the WGV opening at the target point (point B in FIG. 5) in the current deceleration request.

  According to the routine shown in FIG. 7 described above, when the shift from the scavenge region to the low load region is performed (deceleration), it is prohibited to open the WGV 34 until the valve overlap amount is reduced to a predetermined value. The As a result, the scavenge gas blown from the intake system to the exhaust system can be prevented from flowing directly into the high-temperature catalyst 36 via the exhaust bypass passage 32 without passing through the turbine 20b. For this reason, overheating of the catalyst 36 can be suppressed.

  By the way, in the second embodiment described above, the WGV control is intended for the transition from the scavenge region where the gas blows from the intake system to the exhaust system through the combustion chamber to the low load region (during deceleration). I explained. However, as described above, when the EGR valve 40 is opened under the condition that the intake pressure is higher than the exhaust pressure, the gas from the intake system to the exhaust system via the EGR passage 38 (in this case) A fresh air) will occur. Even at the time of transition from the high load region where gas blow-through occurs through the EGR passage 38 to the low load region (deceleration), if the WGGV 34 is opened immediately, the turbine 20b cannot pass through. The overheating of the catalyst 36 becomes a concern due to the blow-by gas (fresh air) that directly flows into the catalyst 36 without being. Therefore, instead of determining the scavenge area in step 100, or in addition to determining the scavenge area, it is determined whether or not it is an area where gas blow-through occurs through the EGR passage 38, and instead of reducing the valve overlap amount, Alternatively, the opening of the WGV 34 may be prohibited until the opening degree of the EGR valve 40 decreases.

  In the above-described second embodiment, the intake variable valve mechanism 42 and the exhaust variable valve mechanism 44 correspond to the “overlap amount adjusting mechanism” in the second aspect of the invention. Further, when the ECU 50 executes the determinations of the steps 100 and 200, the “driving region transition determination means” in the second invention executes the processing of the step 204 when the determination of the step 200 is established. As a result, the “deceleration overlap amount reducing means” in the second invention executes the processing in step 206 when the determination in step 200 is satisfied, whereby the “deceleration waste gate in the second invention”. "Opening prohibition means" is realized respectively.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 14 Exhaust passage 18 Air flow meter 20 Turbocharger 20a Compressor 20b Turbine 24 Throttle valve 26 Intake pressure sensor 28 Fuel injection valve 30 Spark plug 32 Exhaust bypass passage 34 Waste gate valve (WGV)
36 Exhaust purification catalyst 38 EGR passage 40 EGR valve 42 Intake variable valve mechanism 44 Exhaust variable valve mechanism 46 Intake cam angle sensor 48 Exhaust cam angle sensor 50 ECU (Electronic Control Unit)
52 Crank angle sensor

Claims (3)

A turbocharger having a turbine operating by exhaust energy in the exhaust passage;
An exhaust bypass passage that branches off from the exhaust passage at a portion upstream of the turbine and merges with the exhaust passage at a portion downstream of the turbine;
A waste gate valve capable of switching opening and closing of the exhaust bypass passage;
An exhaust purification catalyst for purifying exhaust gas, disposed in the exhaust passage downstream of the downstream portion;
A gas blow-by determination means for determining whether or not gas blow-through has occurred through the combustion chamber or the exhaust gas recirculation passage from the intake system to the exhaust system;
Waste gate opening prohibiting means for prohibiting valve opening of the waste gate valve when it is determined by the gas blow-through determining means that the gas blow-through occurs;
A control device for an internal combustion engine with a supercharger. An overlap amount adjusting mechanism for adjusting a valve overlap amount between the intake valve opening period and the exhaust valve opening period;
An operation region transition determination unit that determines whether or not a transition of the operation region from the region determined to cause the gas blow-by by the gas blow-out determination unit to be performed is performed;
When the transition of the operation region is performed, the deceleration overlap amount reduction means for reducing the valve overlap amount;
When the shift of the operation region is performed, the deceleration waste gate opening prohibiting means for prohibiting the valve opening of the waste gate valve until the valve overlap amount is reduced by the deceleration valve overlap amount reducing means;
The control device for an internal combustion engine with a supercharger according to claim 1, further comprising: A catalyst temperature acquisition means for acquiring the temperature of the exhaust purification catalyst;
3. The internal combustion engine with a supercharger according to claim 1, wherein the waste gate opening prohibiting unit prohibits the opening of the waste gate valve when the temperature of the exhaust purification catalyst is equal to or higher than a predetermined temperature. Engine control device.

Images