JP5817634B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly, to a control device for an internal combustion engine including a supercharger and a waste gate valve.

  As a conventional technique, for example, as disclosed in Japanese Patent Application Laid-Open No. 2009-228486, a control device for an internal combustion engine including a supercharger and a waste gate valve is known. In the prior art, the catalyst temperature is controlled by opening and closing the waste gate valve.

JP 2009-228486 A JP-A-4-370327 JP-A-4-31625 JP 2011-214454 A

  By the way, in the above-described prior art, when the exhaust gate temperature on the upstream side of the turbine is higher than the catalyst temperature, when the waste gate valve is closed to lower the catalyst temperature, the temperature of the exhaust pipe further increases. There is a possibility that the exhaust pipe is thermally deteriorated. In addition, when there is a demand for greatly reducing the catalyst temperature, there is a problem that even if the waste gate valve is opened, the catalyst temperature cannot be sufficiently lowered by itself.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an internal combustion engine capable of suppressing heat deterioration of an exhaust pipe and a catalyst in a well-balanced manner by using a waste gate valve. It is to provide an engine control device.

A first invention is a catalyst for purifying exhaust gas of an internal combustion engine;
A turbocharger having a turbine provided in an exhaust passage of an internal combustion engine and a compressor provided in an intake passage, and supercharging intake air using exhaust pressure;
An exhaust bypass passage connected to the exhaust passage in parallel with the turbine of the supercharger and bypassing the turbine;
A wastegate valve for adjusting the amount of exhaust gas flowing through the exhaust bypass passage;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst as the catalyst temperature;
An exhaust pipe temperature acquisition means for acquiring, as an upstream exhaust pipe temperature, a temperature upstream of the turbine among the exhaust pipes constituting the exhaust passage;
When the catalyst temperature is higher than a predetermined high temperature determination value and the upstream exhaust pipe temperature is higher than the catalyst temperature, the opening of the waste gate valve is increased, and the catalyst temperature is higher than the high temperature determination value. And when the upstream exhaust pipe temperature is lower than the catalyst temperature, WGV control means for reducing the opening of the waste gate valve;
It is characterized by providing.

The second invention is connected to the intake passage in parallel with the compressor of the supercharger, and an intake bypass passage that bypasses the compressor;
An air bypass valve capable of recirculating intake air from the downstream side to the upstream side of the compressor via the intake bypass passage;
ABV control means for increasing the opening degree of the air bypass valve when the opening degree of the waste gate valve is decreased by the WGV control means.

A third invention provides a catalyst for purifying exhaust gas of an internal combustion engine,
A turbocharger having a turbine provided in an exhaust passage of an internal combustion engine and a compressor provided in an intake passage, and supercharging intake air using exhaust pressure;
An exhaust bypass passage connected to the exhaust passage in parallel with the turbine of the supercharger and bypassing the turbine;
A wastegate valve for adjusting the amount of exhaust gas flowing through the exhaust bypass passage;
An intake bypass passage that is connected to the intake passage in parallel with the compressor of the supercharger and bypasses the compressor;
An air bypass valve capable of recirculating intake air from the downstream side to the upstream side of the compressor via the intake bypass passage;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst as the catalyst temperature;
WGV / ABV control means for reducing the opening degree of the waste gate valve and increasing the opening degree of the air bypass valve when the catalyst temperature is higher than a predetermined high temperature judgment value, To do.

  According to the first invention, when the temperature of the upstream portion (upstream exhaust pipe portion) of the exhaust passage is higher than the catalyst temperature, by increasing the opening of the waste gate valve (WGV), The amount of exhaust gas staying in the upstream exhaust pipe can be reduced. Thereby, upstream exhaust pipe temperature can be lowered | hung and thermal deterioration of an upstream exhaust pipe part can be suppressed. On the other hand, when the upstream exhaust pipe temperature is lower than the catalyst temperature, the amount of exhaust gas passing through the turbine can be increased by decreasing the opening of the WGV. Thereby, the exhaust heat can be recovered by the turbine, the exhaust temperature can be lowered at the position of the catalyst, and the thermal deterioration of the catalyst can be suppressed. Accordingly, it is possible to suppress thermal degradation of the upstream exhaust pipe portion and the catalyst, which has a higher temperature, by controlling the WGV and to suppress thermal degradation in a well-balanced manner.

  According to the second invention, when the opening of the WGV is decreased, the opening of the air bypass valve (ABV) can be increased. As a result, the work of the supercharger can be reduced and the back pressure can be reduced, so that the ignition timing can be advanced without causing knocking and the exhaust temperature can be lowered. Further, when the opening degree of the WGV is decreased, the amount of exhaust gas passing through the turbine is increased, and the exhaust temperature can be further lowered at the position of the catalyst. Therefore, even when a request for significantly reducing the catalyst temperature occurs, this request can be satisfied, and thermal deterioration of the catalyst can be suppressed without using an OT increase.

  According to the third invention, when the catalyst temperature is higher than the high temperature determination value, the opening degree of the WGV can be decreased and the opening degree of the ABV can be increased. As a result, the same effects as those of the second invention can be obtained, and even when a request for greatly reducing the catalyst temperature occurs, this request can be satisfied.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a characteristic diagram which shows the relationship between the catalyst temperature in the state which opened WGV, and (lambda) 1 limit. It is explanatory drawing which shows the expansion effect of (lambda) 1 area | region by WGV control and ABV control. It is a characteristic diagram which shows the relationship between the open / close state of WGV and ABV, and a turbo work amount. It is a characteristic diagram which shows the relationship between the open / closed state of WGV and ABV, and a back pressure. It is a characteristic line figure showing the relation between upstream exhaust pipe temperature (exhaust manifold temperature: Tex) and load (KL). It is a characteristic diagram which shows the relationship between catalyst temperature (Tsc) and load. It is a characteristic diagram which shows the relationship between exhaust air fuel ratio (A / F) and torque (TQ). In Embodiment 1 of this invention, it is a flowchart of the control performed by ECU. In Embodiment 2 of this invention, it is a flowchart of the control performed by ECU.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
The first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system of the present embodiment includes a multi-cylinder engine 10 as an internal combustion engine. Although FIG. 1 illustrates one cylinder of the engine, the present invention is applied to an internal combustion engine having an arbitrary number of cylinders. Each cylinder of the engine 10 has a combustion chamber 14 formed by a piston 12, and the piston 12 is connected to a crankshaft 16. The engine 10 also includes an intake passage 18 that sucks intake air into each cylinder, and an exhaust passage 20 that discharges exhaust gas from each cylinder. An electronically controlled throttle valve 22 that adjusts the intake air amount and a surge tank 24 that reduces intake pulsation are disposed in the intake passage 18. The exhaust passage 20 is provided with a catalyst 26 such as a three-way catalyst for purifying exhaust gas. In each cylinder, a fuel injection valve 28 for injecting fuel into the intake passage 18 (intake port), an ignition plug 30 for igniting an air-fuel mixture in the cylinder, and intake air for opening and closing the intake passage 18 with respect to the cylinder A valve 32 and an exhaust valve 34 for opening and closing the exhaust passage 20 with respect to the inside of the cylinder are provided.

  The engine 10 includes a supercharger 36 that supercharges intake air using exhaust pressure. The supercharger 36 includes a turbine 38 disposed in the exhaust passage 20 and a compressor 40 disposed in the intake passage 18, and the turbine 38 that rotates by receiving exhaust pressure drives the compressor 40 to perform suction. Supercharge the air. In addition, the site | part located in the upstream of the turbine 38 among the exhaust pipes which comprise the exhaust passage 20 becomes the upstream exhaust pipe part 20a. The exhaust passage 20 is connected to an exhaust bypass passage 42 that is arranged in parallel with the turbine 38 and bypasses the turbine 38. The exhaust bypass passage 42 is provided with an electromagnetically driven waste gate valve (WGV) 44 that adjusts the flow rate of exhaust gas flowing through the exhaust bypass passage 42. During engine operation, for example, the supercharging pressure is controlled by changing the opening of the WGV 44 based on the engine operating state and the output of the intake pressure sensor 66, thereby preventing excessive supercharging and improving fuel efficiency. can do. As the WGV 44 used in the present invention, in addition to the electromagnetically driven valve, for example, a valve of a type in which a negative pressure pump and an electromagnetic valve are combined can be employed.

  On the other hand, the intake passage 18 is provided with an intercooler 46 that cools intake air whose temperature has increased due to supercharging. The intake passage 18 is provided with an intake bypass passage 48 that is arranged in parallel with the compressor 40 and bypasses the compressor 40. The intake bypass passage 48 is provided with an electromagnetically driven air bypass valve (ABV) 50 that can recirculate intake air from the downstream side to the upstream side of the compressor 40 via the intake bypass passage 48. In an engine equipped with a supercharger 36, if the throttle valve 22 is suddenly closed during deceleration, the pressure between the compressor 40 and the throttle valve 22 may be excessive or intake pulsation may occur. In such a case, the pressure on the downstream side of the compressor 40 can be reduced by opening the ABV 50 and releasing the intake air (supercharging pressure) from the downstream side of the compressor 40 to the upstream side.

  Next, a system control system will be described. The system according to the present embodiment includes a sensor system composed of various sensors necessary for driving the engine and the vehicle, and an ECU (Engine Control Unit) 80 that controls the operation of the engine. The sensor system includes a crank angle sensor 60, an air flow sensor 62, a water temperature sensor 64, an intake pressure sensor 66, an air-fuel ratio sensor 68, a catalyst temperature sensor 70, and the like. First, the sensor system will be described. The crank angle sensor 60 detects the rotation of the crankshaft 16, and the air flow sensor 62 detects the intake air amount. The water temperature sensor 64 detects the water temperature of the engine cooling water, and the intake pressure sensor 66 detects the intake pressure (supercharging pressure). Further, the air-fuel ratio sensor 68 detects the exhaust air-fuel ratio, and the catalyst temperature sensor 70 constitutes catalyst temperature acquisition means that detects (acquires) the temperature (bed temperature) of the catalyst 26 as the catalyst temperature. In addition, the sensor system includes a throttle sensor that detects the throttle opening, an accelerator sensor that detects the accelerator operation amount of the driver, and the like.

  The ECU 80 is configured by an arithmetic processing unit that includes a storage circuit including a ROM, a RAM, a nonvolatile memory, and the like, and an input / output port. Each sensor constituting the sensor system is connected to the input side of the ECU 80. In addition to the fuel injection valve 28 and the spark plug 30 of each cylinder, a WGV 44 and an ABV 50 are connected to the output side of the ECU 80. The ECU 80 controls the operation by driving each actuator based on the engine operation information detected by the sensor system. Specifically, the crank angle and the engine speed (engine speed) are detected based on the output of the crank angle sensor 60, the intake air amount is detected by the air flow sensor 62, and the engine speed and the intake air amount are detected. Based on this, the load factor (engine load) is calculated, and the fuel injection amount is calculated based on the intake air amount, load factor, water temperature, and the like. Then, fuel injection timing is determined based on the crank angle, and fuel injection control is executed by driving the fuel injection valve 28. Further, the ignition timing is determined according to the operating state of the engine and the like, and ignition control for driving the spark plug 30 is executed. Thus, the air-fuel mixture is combusted in each cylinder and the engine is operated.

  Further, the ECU 80 executes known air-fuel ratio control for feedback control of the air-fuel ratio based on the output of the air-fuel ratio sensor 68 so that the exhaust air-fuel ratio matches the stoichiometric air-fuel ratio (stoichiometric). According to the air-fuel ratio control, the exhaust air-fuel ratio can be matched with the exhaust purification window of the catalyst 26, and the exhaust purification ability of the catalyst can be exhibited to the maximum. Further, when the catalyst temperature exceeds a predetermined OT temperature and enters an OT (Over Temperature) state, the ECU 80 gives priority to preventing thermal deterioration of the catalyst 26 over the air-fuel ratio control and increases the fuel injection amount. The catalyst OT prevention control is executed. Here, the OT temperature is a lower limit value of a temperature at which the thermal degradation of the catalyst 26 proceeds. When the catalyst temperature exceeds the OT temperature, an increase in fuel (OT increase) is required to cool the catalyst 26, so that the air-fuel ratio control for controlling the air-fuel ratio λ = 1 (stoichiometric) cannot be performed. In the following description, an operation region in which air-fuel ratio control can be performed is referred to as “λ1 region”, and a limit of the operation region is referred to as “λ1 limit”. In addition, the temperature of the upstream exhaust pipe portion 20a may exceed the OT temperature (that is, the lower limit value of the temperature at which the thermal degradation of the upstream exhaust pipe portion 20a progresses) to be in the OT state. In this case, as described later, it is necessary to suppress thermal deterioration of the upstream exhaust pipe portion 20a.

[Features of Embodiment 1]
FIG. 2 is a characteristic diagram showing the relationship between the catalyst temperature and the λ1 limit when the WGV is opened. In an engine with a supercharger, when mileage optimum control is performed to control the WGV 44 at an intermediate opening for the purpose of improving fuel efficiency, the λ1 limit is set to the OT state of the catalyst 26 as shown in FIG. Will be decided accordingly. This is due to the following reason. When the WGV 44 is open, the amount of exhaust heat recovered by the turbine 38 decreases. That is, since the high-temperature exhaust gas that reaches the catalyst 26 via the exhaust bypass passage 42 increases, the catalyst temperature rises and OT easily occurs. On the other hand, if the WGV 44 is held in a closed state to enlarge the λ1 region, the phenomenon of back pressure increase → ignition timing delay → exhaust temperature increase → fuel consumption deterioration & λ1 region reduction occurs, and the λ1 region is expanded. It becomes difficult to do. On the other hand, when the WGV 44 is closed to lower the catalyst temperature in a state where the temperature of the upstream exhaust pipe portion 20a (hereinafter referred to as the upstream exhaust pipe temperature) is higher than the catalyst temperature, the upstream exhaust pipe temperature further increases. There is a possibility that the exhaust pipe is thermally deteriorated. In addition, when there is a request to greatly reduce the catalyst temperature, even if the WGV 44 is opened, it is difficult to sufficiently reduce the catalyst temperature by itself.

  For this reason, in the present embodiment, the WGV 44 is opened and closed in the vicinity of the λ1 limit to prevent OT of the catalyst and the exhaust pipe (WGV control). However, since the back pressure increases when the WGV 44 is closed, the ignition timing is retarded in the knock region, and the λ1 region is not expanded due to a rise in exhaust temperature and a decrease in torque caused by this. Therefore, in the present embodiment, when the WGV 44 is closed, the ABV 50 is opened to reduce the back pressure and advance the ignition timing (ABV control). That is, when the ABV 50 is opened, the work (turbo work) of the supercharger 36 is reduced and the back pressure is lowered, so that the ignition timing can be advanced without causing knock. Thereby, it is possible to increase the torque while lowering the exhaust temperature and suppressing the fuel injection amount.

  More specifically, in the WGV control, when the catalyst temperature is higher than a predetermined OT temperature (high temperature determination value) and the upstream exhaust pipe temperature is higher than the catalyst temperature, the opening degree of the WGV 44 is increased ( Preferably, the opening of the WGV 44 is set to a half-open state, that is, an intermediate opening. At this time, in the ABV control, the opening degree of the ABV 50 is decreased (preferably, fully closed). According to this control, when the upstream exhaust pipe temperature is higher than the catalyst temperature, the amount of exhaust gas staying in the upstream exhaust pipe section 20a can be reduced by increasing the opening of the WGV 44. Thereby, upstream exhaust pipe temperature can be reduced and the thermal deterioration of the upstream exhaust pipe part 20a can be suppressed. The upstream exhaust pipe temperature may be directly detected by a temperature sensor installed in the upstream exhaust pipe section 20a. However, without using a temperature sensor or the like, the upstream exhaust pipe temperature is estimated based on, for example, the engine speed and the engine temperature. It may be detected. These temperature sensors and detection methods constitute the exhaust pipe temperature acquisition means of the present invention.

  In the WGV control, when the catalyst temperature is higher than the OT temperature and the upstream exhaust pipe temperature is lower than the catalyst temperature, the opening degree of the WGV 44 is decreased (preferably, fully closed). At this time, in the ABV control, the opening degree of the ABV 50 is increased (preferably, the opening degree of the ABV 50 is adjusted according to the target load). According to this control, when the upstream exhaust pipe temperature is lower than the catalyst temperature, the amount of exhaust gas passing through the turbine 38 can be increased by decreasing the opening of the WGV 44. As a result, exhaust heat can be recovered by the turbine 38, the exhaust temperature can be lowered at the position of the catalyst 26, and thermal deterioration of the catalyst 26 can be suppressed. Further, the effects described later can be obtained by closing the WGV 44 and opening the ABV 50.

  As described above, in the present embodiment, when the catalyst temperature is higher than the OT temperature, thermal degradation of the higher temperature of the upstream exhaust pipe portion 20a and the catalyst 26 can be suppressed by WGV control. Further, when it is desired to greatly reduce the catalyst temperature, it is possible to realize this by controlling the opening degrees of both the WGV 44 and the ABV 50. Therefore, thermal deterioration of the upstream exhaust pipe portion 20a and the catalyst 26 can be suppressed with a good balance.

  Next, effects of the WGV control and the ABV control will be described. FIG. 3 is an explanatory diagram showing the effect of enlarging the λ1 region by WGV control and ABV control. In this figure, “◎” indicates that there is a significant effect on the reduction in turbo work and back pressure, “○” indicates that there is an effect, and “△” indicates that there is a slight effect. It shows that there is. 4 is a characteristic diagram showing the relationship between the open / closed state of WGV and ABV and the turbo work amount, and FIG. 5 is a characteristic diagram showing the relationship between the open / closed state of WGV and ABV and back pressure. . P4 in FIG. 5 indicates the pressure in the upstream exhaust pipe portion 20a. FIG. 6 is a characteristic line diagram showing the relationship between the upstream exhaust pipe temperature (exhaust manifold temperature: Tex) and the load (KL), and FIG. 7 is a characteristic line showing the relationship between the catalyst temperature (Tsc) and the load. FIG. 8 is a characteristic diagram showing the relationship between the exhaust air / fuel ratio (A / F) and the torque (TQ).

  According to the experiments of the present inventors, when the WGV 44 is closed and the ABV 50 is opened, as shown in FIGS. 3 to 5, a remarkable effect is obtained on the reduction of the turbo work amount and the reduction of the back pressure. Turned out to be. In other words, in this case, for example, compared with a case where the WGV and ABV are closed, the turbo work amount is reduced and the back pressure is reduced, so that the ignition timing can be advanced without causing knock. . Thereby, as shown in FIG.6 and FIG.7, exhaust temperature (upstream exhaust pipe temperature) and catalyst temperature can be reduced. Therefore, the ignition timing can be advanced and the OT increase amount is not required, so that the torque can be increased while suppressing the fuel injection amount. And as shown in FIG. 8, the driving | running area | region which does not use OT increase, ie, (lambda) 1 area | region, can be expanded, and exhaust emission can be improved.

[Specific Processing for Realizing Embodiment 1]
Next, specific processing for realizing the above-described control will be described with reference to FIG. FIG. 9 is a flowchart of the control executed by the ECU in the first embodiment of the present invention. The routine shown in this figure is repeatedly executed while the engine is operating. In the routine shown in FIG. 9, first, in step 100, it is determined whether or not the λ1 limit is reached, that is, whether or not the catalyst temperature is higher than the OT temperature (high temperature determination value). If the determination in step 100 is satisfied, the λ1 limit has been reached and OT increase is necessary (air-fuel ratio control cannot be performed). In this case, the routine proceeds to step 102 where it is determined whether or not the upstream exhaust pipe temperature (exhaust manifold temperature) is higher than the catalyst temperature.

  If the determination in step 102 is satisfied, the upstream exhaust pipe temperature has reached the OT temperature. Therefore, in step 104, the WGV 44 is opened in a half-open state, and in step 106, the ABV 50 is closed. Next, in step 108, it is determined whether or not the upstream exhaust pipe temperature has decreased until it becomes equal to the catalyst temperature. If this determination is satisfied, in step 110, in order to suppress thermal deterioration of the catalyst 26. OT increase is executed. On the other hand, if the determination in step 108 is not satisfied, the processes in steps 102 to 108 are repeatedly executed until this determination is satisfied.

  If the determination in step 102 is not established, only the catalyst temperature has reached the OT temperature according to the determination in step 100. Therefore, the process proceeds to step 112 and the WGV 44 is closed. Subsequently, in step 114, the ABV 50 is opened in a half-open state, and the process proceeds to step 108. In this case, the opening degree of the ABV 50 may be variably set according to the target load KL. Thus, in the present embodiment, the processing of steps 104 and 106 (exhaust pipe OT countermeasures) and the processing of steps 112 and 114 (catalyst OT countermeasures) can be used properly according to the temperature state. Thereby, the opening degree of the WGV 44 can be controlled so that only one of the upstream exhaust pipe portion 20a and the catalyst 26 is not biased, and unnecessary OT increase can be avoided. In the process of step 114, the ABV 50 is opened to reduce the turbo work amount and the back pressure. As a result, the ignition timing can be advanced, the exhaust temperature can be lowered, the torque can be improved, and the λ1 region can be expanded.

  On the other hand, if the determination in step 100 is not established, the stoichiometry can be maintained by the air-fuel ratio control, so the routine proceeds to step 116 and the ABV 50 is closed. In step 118, the WGV 44 is opened. That is, in the intermediate rotation / intermediate load operation region (partial region), the WGV 44 is basically opened to improve fuel efficiency. In this case, the opening degree of the WGV 44 may be variably set according to the target load KL. Next, in step 120, this routine is terminated without executing the OT increase.

  In the first embodiment, steps 100, 102, 104, and 112 in FIG. 9 show a specific example of the WGV control means in claim 1, and steps 106 and 114 show a specific example of the ABV control means in claim 2. Is shown.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, in the same configuration as in the first embodiment (FIG. 1), when the catalyst temperature is higher than the OT temperature, the WGV opening is increased and the ABV opening is decreased. It is a feature. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
As described above, in the vicinity of the λ1 limit, when the opening of the WGV 44 is decreased, the back pressure increases, and the ignition timing is retarded in the knock region. As a result, the exhaust temperature and torque decrease, and it is difficult to expand the λ1 region. Therefore, in the present embodiment, when the catalyst temperature is higher than the OT temperature, the opening degree of the WGV 44 is increased and the opening degree of the ABV 50 is decreased. Thereby, substantially the same operational effects as in the first embodiment can be obtained. That is, according to the present embodiment, when the catalyst 26 is in the OT state, the turbo work amount can be reduced and the back pressure can be reduced. Thereby, the ignition timing can be advanced and the exhaust gas temperature can be lowered. Further, the amount of exhaust gas passing through the turbine 38 increases, so that the exhaust temperature at the position of the catalyst 26 can be further lowered. Therefore, according to the present embodiment, even when a request for greatly reducing the catalyst temperature occurs, this request can be satisfied, and thermal deterioration of the catalyst 26 can be suppressed without using an OT increase. .

[Specific Processing for Realizing Embodiment 2]
Next, specific processing for realizing the above-described control will be described with reference to FIG. FIG. 10 is a flowchart of control executed by the ECU in the second embodiment of the present invention. The routine shown in this figure is repeatedly executed while the engine is operating. In the routine shown in FIG. 10, first, in step 200, it is determined whether or not the λ1 limit is satisfied. If this determination is established, the catalyst temperature is higher than the OT temperature (high temperature determination value) in step 202. It is determined whether or not.

  When the determination in step 202 is established, the process proceeds to step 204, and the opening degree of the WGV 44 is decreased (preferably fully closed). In step 206, the opening of the ABV 50 is set to half open (intermediate opening). In this case, the opening degree of the ABV 50 may be variably set according to the target load KL. On the other hand, if the determination in step 202 is not established, the catalyst 26 is not in the OT state, and thus this routine is terminated. On the other hand, if the determination in step 200 is not established, the process proceeds to steps 208 and 210, and the same processing as steps 116 and 118 in the first embodiment (FIG. 9) is executed.

  In the second embodiment, steps 204 and 206 in FIG. 10 show a specific example of the WGV / ABV control means in claim 2. In the first embodiment, the case where the WGV control and the ABV control are used in combination is exemplified. However, the present invention is not limited to this, and only the WGV control may be executed. Further, in the first and second embodiments, the OT temperature is exemplified as the high temperature determination value. However, the present invention is not limited to this, and the high temperature determination value may be set to an arbitrary temperature according to a design requirement or the like. Is.

10 Engine (Internal combustion engine)
12 piston 14 combustion chamber 16 crankshaft 18 intake passage 20 exhaust passage 20a upstream exhaust pipe portion 22 throttle valve 24 surge tank 26 catalyst 28 fuel injection valve 30 ignition plug 32 intake valve 34 exhaust valve 36 supercharger 38 turbine 40 compressor 42 exhaust Bypass passage 44 Waste gate valve 46 Intercooler 48 Intake bypass passage 50 Air bypass valve 60 Crank angle sensor 62 Air flow sensor 64 Water temperature sensor 66 Intake pressure sensor 68 Air-fuel ratio sensor 70 Catalyst temperature sensor 80 ECU

Claims (3)

A catalyst provided in an exhaust passage of the internal combustion engine for purifying exhaust gas;
A turbocharger having a turbine provided in the exhaust passage and a compressor provided in the intake passage, and supercharging intake air using exhaust pressure;
One end is connected to the exhaust passage upstream of the turbine of the supercharger , and the other end is connected to the exhaust passage at a position downstream of the turbine and upstream of the catalyst to bypass the turbine A passage,
A wastegate valve for adjusting the amount of exhaust gas flowing through the exhaust bypass passage;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst as the catalyst temperature;
An exhaust pipe temperature acquisition means for acquiring, as an upstream exhaust pipe temperature, a temperature upstream of the turbine among the exhaust pipes constituting the exhaust passage;
When the catalyst temperature is higher than a predetermined high temperature determination value and the upstream exhaust pipe temperature is higher than the catalyst temperature, the opening of the waste gate valve is increased, and the catalyst temperature is higher than the high temperature determination value. And when the upstream exhaust pipe temperature is lower than the catalyst temperature, WGV control means for reducing the opening of the waste gate valve;
A control device for an internal combustion engine, comprising: An intake bypass passage that is connected to the intake passage in parallel with the compressor of the supercharger and bypasses the compressor;
An air bypass valve capable of recirculating intake air from the downstream side to the upstream side of the compressor via the intake bypass passage;
ABV control means for increasing the opening of the air bypass valve when the opening of the waste gate valve is decreased by the WGV control means;
The control device for an internal combustion engine according to claim 1, comprising: A catalyst for purifying exhaust gas of an internal combustion engine;
A turbocharger having a turbine provided in an exhaust passage of an internal combustion engine and a compressor provided in an intake passage, and supercharging intake air using exhaust pressure;
An exhaust bypass passage connected to the exhaust passage in parallel with the turbine of the supercharger and bypassing the turbine;
A wastegate valve for adjusting the amount of exhaust gas flowing through the exhaust bypass passage;
An intake bypass passage that is connected to the intake passage in parallel with the compressor of the supercharger and bypasses the compressor;
An air bypass valve capable of recirculating intake air from the downstream side to the upstream side of the compressor via the intake bypass passage;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst as the catalyst temperature;
An exhaust pipe temperature acquisition means for acquiring, as an upstream exhaust pipe temperature, a temperature upstream of the turbine among the exhaust pipes constituting the exhaust passage;
The catalyst temperature is higher rather than a predetermined high-temperature determination value, and wherein when the upstream exhaust pipe temperature is higher than the catalyst temperature, with increasing degree of opening of the waste gate valve, the opening degree of the air bypass valve First WGV / ABV control means for reducing
When the catalyst temperature is higher than the high temperature determination value and the upstream exhaust pipe temperature is lower than the catalyst temperature , the opening of the waste gate valve is compared with the first WGV / ABV control means. And a second WGV / ABV control means for increasing the opening of the air bypass valve,
A control device for an internal combustion engine, comprising:

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