JP7192673B2 - Internal combustion engine control system - Google Patents

Description

The present invention relates to a control system for an internal combustion engine with a turbocharger in parallel.

Various techniques have been proposed for a control system for an internal combustion engine having a turbocharger in parallel. For example, in the failure diagnosis device for an internal combustion engine described in Patent Document 1 below, only the first turbocharger of the first turbocharger and the second turbocharger provided in parallel operates, and the second turbocharger operates. Switching control is performed between a "single turbo mode" in which the turbocharger does not operate and a "twin turbo mode" in which the first and second turbochargers operate. Also, in the single turbo mode, both the intake switching valve and the exhaust switching valve are closed, and the intake bypass valve is opened.

In the single turbo mode, the controller outputs a valve closing instruction to the intake bypass bus valve when it determines that the atmospheric pressure and the outlet pressure of the compressor of the second turbocharger are equal to each other. After that, when it is determined that the outlet pressure of the compressor of the second supercharger is equal to or lower than the atmospheric pressure, the control unit diagnoses that the intake bypass valve is stuck open.

Further, in the single turbo mode, when the control unit determines that the atmospheric pressure and the outlet pressure of the compressor of the second turbocharger are equal to each other, the control unit outputs an instruction to close the intake bypass bus valve, Outputs a valve opening instruction to the intake switching valve. After that, when the control unit determines that the outlet pressure of the compressor of the second supercharger is higher than the atmospheric pressure and that the outlet pressure of the compressor of the second supercharger is equal to or higher than the pressure of the intake manifold, It is configured to perform a failure diagnosis when the intake switching valve is stuck closed.

Further, in the single turbo mode, the control unit determines that the difference between the atmospheric pressure and the outlet pressure of the compressor of the second turbocharger is equal to or greater than the first pressure threshold, and that the supercharging pressure of the intake manifold is higher than the target supercharging pressure. is determined to be lower than the second pressure threshold for a certain period of time, it is determined that the exhaust gas switching valve is stuck open.

JP 2009-185684 A

However, in the failure diagnosis device for the internal combustion engine described in Patent Document 1, failure diagnosis of the intake switching valve, the exhaust switching valve, and the intake bypass valve is performed only in the single turbo mode. As a result, in the twin-turbo mode, the switching mode from the twin-turbo mode to the single-turbo mode, or the switching mode from the single-turbo mode to the twin-turbo mode, the intake switching valve, the exhaust switching valve, or the intake bypass valve If one of the valves fails, there is a problem that the failure cannot be diagnosed until the single turbo mode is established.

Accordingly, the present invention has been devised in view of the above points, and is capable of diagnosing failures of an exhaust switching valve, an intake switching valve, or an intake bypass valve in each of a plurality of supercharging mode states. It is an object of the present invention to provide an internal combustion engine control system capable of

In order to solve the above problems, a first aspect of the present invention provides a main turbocharger, a sub-turbocharger connected in parallel to the main turbocharger, and a sub-turbine inlet side of the sub-turbocharger connected to the sub-turbine. an exhaust switching valve provided on the upstream side sub-exhaust pipe of the sub-turbocharger; an intake switching valve provided on an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger; An intake bypass valve provided in an intake bypass pipe connecting an upstream side and an inlet side of the main compressor of the main turbocharger, and the exhaust switching valve, the intake switching valve, and the intake bypass valve are closed or A single-turbo mode in which only the main turbocharger is operated and supercharged by switching to the valve-open state, a twin-turbo mode in which the main turbocharger and the sub-turbocharger are operated and supercharged, and from the single-turbo mode to the twin-turbo Valve switching control for setting the supercharging mode to one of the twin switching mode through which the mode is switched and the single switching mode through which the twin turbo mode is switched to the single turbo mode. a supercharging pressure acquiring device for acquiring the supercharging pressure of the intake manifold; a main compressor outlet pressure acquiring device for acquiring the outlet pressure of the main compressor; and a secondary compressor outlet pressure acquiring device for acquiring the outlet pressure of the secondary compressor. and the exhaust switching in accordance with the supercharging mode set by the valve switching control device based on one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the secondary compressor. A control system for an internal combustion engine, comprising: a valve; and a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve.

Next, according to a second invention of the present invention, in the control system for an internal combustion engine according to the first invention, an atmospheric pressure detection device for detecting atmospheric pressure is provided, and the valve switching control device selects the supercharging mode. When the single turbo mode is set, the exhaust switching valve, the intake switching valve, and the intake bypass valve are each controlled to be switched to a closed state, and the failure diagnosis device controls the valve switching control device. a first determination device that determines whether or not the supercharging mode is set to the single turbo mode; and the first determination device determines that the valve switching control device has set the supercharging mode to the single turbo mode. If so, it is determined whether or not the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are in a substantially equal pressure state and the outlet pressure of the sub-compressor is higher than the atmospheric pressure. and a second determination device that determines that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal to each other, and that the outlet pressure of the sub-compressor is the high pressure. This control system for an internal combustion engine performs a failure diagnosis that the intake switching valve is stuck open when it is determined that the pressure is higher than atmospheric pressure.

Next, according to a third invention of the present invention, in the control system for an internal combustion engine according to the first invention or the second invention, an atmospheric pressure detection device for detecting atmospheric pressure is provided, and the valve switching control device comprises: When the supercharging mode is set to the single turbo mode, the exhaust switching valve, the intake switching valve, and the intake bypass valve are controlled to be closed, and the failure diagnosis device controls the a first determination device that determines whether or not a valve switching control device has set the supercharging mode to the single turbo mode; , if the outlet pressure of the main compressor is different from the outlet pressure of the sub-compressor, and is the outlet pressure of the sub-compressor higher than the atmospheric pressure? a third determination device for determining whether the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different by the third determination device, and the outlet pressure of the sub-compressor is a pressure higher than the atmospheric pressure, the control system for an internal combustion engine diagnoses that the exhaust switching valve is stuck open.

Next, according to a fourth invention of the present invention, the control system for an internal combustion engine according to one of the first to third inventions is provided with an atmospheric pressure detection device for detecting atmospheric pressure, When the supercharging mode is set to the twin switching mode, the valve switching control device maintains the intake switching valve in a closed state and switches the exhaust switching valve and the intake bypass valve to an open state. The failure diagnosis device includes a fourth determination device that determines whether or not the valve switching control device has set the supercharging mode to the twin switching mode, and the valve switching is performed by the fourth determination device. A fifth judgment for judging whether or not the pressure at the outlet of the sub-compressor and the atmospheric pressure are substantially equal when the control device judges that the supercharging mode is set to the twin switching mode. and, when the fifth determination device determines that the pressure at the outlet of the sub-compressor and the atmospheric pressure are substantially equal to each other, the exhaust switching valve is stuck closed. It is a control system for an internal combustion engine that performs fault diagnosis with

Next, a fifth invention of the present invention is the control system for an internal combustion engine according to one of the first to fourth inventions, wherein the valve switching control device switches the supercharging mode to the When the twin turbo mode is set, the open state of the exhaust switching valve is maintained, the intake switching valve is switched from the closed state to the open state, and the intake bypass valve is closed from the open state. and the failure diagnosis device includes: a sixth determination device for determining whether or not the valve switching control device has set the supercharging mode to the twin turbo mode; When the valve switching control device determines that the supercharging mode is set to the twin-turbo mode, it determines whether or not the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different. and a seventh determination device for determining, when the seventh determination device determines that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are in different pressure states, the switching of the intake air. A control system for an internal combustion engine that diagnoses a stuck closed valve.

Next, a sixth aspect of the present invention provides an outlet temperature detection device for detecting the outlet temperature of the main compressor in the control system for an internal combustion engine according to one of the first to fifth aspects of the invention. wherein, when the supercharging mode is set to the twin-turbo mode, the valve switching control device maintains the open state of the exhaust switching valve and opens the intake switching valve from the closed state. state, and controls the intake bypass valve to switch from the open state to the closed state, and the failure diagnosis device determines whether the valve switching control device has set the supercharging mode to the twin turbo mode. and a sixth determination device for determining whether the supercharging pressure of the intake manifold reaches the target when the sixth determination device determines that the valve switching control device has set the supercharging mode to the twin turbo mode. an eighth determination device that determines whether the pressure is lower than the supercharging pressure and the outlet temperature of the main compressor is equal to or higher than a first temperature threshold, wherein the eighth determination device determines whether the When it is determined that the supercharging pressure of the intake manifold is lower than the target supercharging pressure and the outlet temperature of the main compressor is equal to or higher than the first temperature threshold, the intake bypass valve is stuck open. It is a control system for an internal combustion engine that performs a fault diagnosis that the engine is running.

Next, according to a seventh invention of the present invention, the internal combustion engine control system according to one of the first to sixth inventions is provided with an atmospheric pressure detection device for detecting atmospheric pressure, When the supercharging mode is set to the single switching mode, the valve switching control device switches the exhaust switching valve and the intake switching valve to a closed state, and switches the intake bypass valve to an open state. and the failure diagnosis device includes a ninth determination device that determines whether the valve switching control device has set the supercharging mode to the single switching mode, and the valve switching control by the ninth determination device When the apparatus determines that the supercharging mode is set to the single switching mode, the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal to each other, and the outlet of the sub-compressor a tenth determination device for determining whether the pressure is higher than the atmospheric pressure, wherein the tenth determination device determines that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal. The internal combustion engine, wherein when it is determined that the outlet pressure of the sub-compressor is higher than the atmospheric pressure in a constant pressure state, a failure diagnosis is made that the intake switching valve is stuck open. control system.

Next, an eighth invention of the present invention is an internal combustion engine control system according to one of the first to seventh inventions, comprising an atmospheric pressure detection device for detecting atmospheric pressure, When the supercharging mode is set to the single switching mode, the valve switching control device switches the exhaust switching valve and the intake switching valve to a closed state, and switches the intake bypass valve to an open state. and the failure diagnosis device includes a ninth determination device that determines whether the valve switching control device has set the supercharging mode to the single switching mode, and the valve switching control by the ninth determination device When the device determines that the supercharging mode is set to the single switching mode, the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different, and the outlet pressure of the sub-compressor is a pressure higher than the atmospheric pressure; and a control system for an internal combustion engine.

Next, a ninth aspect of the present invention is a control system for an internal combustion engine according to the first aspect of the invention, in which a main variable nozzle mechanism adjusts the flow velocity of exhaust gas to the main turbine of the main turbocharger by adjusting the nozzle opening. a sub-variable nozzle mechanism that adjusts the flow velocity of the exhaust gas to the sub-turbine according to the opening of the nozzle; and a nozzle that performs opening adjustment control of the nozzle opening of each of the main variable nozzle mechanism and the sub-variable nozzle mechanism. a control device; and a first failure determination device for determining whether or not the failure diagnosis device has determined whether any one of the exhaust switching valve, the intake switching valve, and the intake bypass valve is stuck open. and when the first failure determination device determines that any one of the exhaust switching valve, the intake switching valve, and the intake bypass valve is stuck open, the valve The switching control device sets each of the exhaust switching valve and the intake switching valve to an open state, sets the intake bypass valve to a closed state, and fixes the supercharging mode to the twin turbo mode. The nozzle control device is a control system for an internal combustion engine that controls to fully open the nozzle openings of the main variable nozzle mechanism and the sub-variable nozzle mechanism.

Next, according to a tenth aspect of the present invention, in the control system for an internal combustion engine according to the first aspect or the ninth aspect, the flow velocity of the exhaust gas to the main turbine of the main turbocharger is adjusted by the nozzle opening. a sub-variable nozzle mechanism that adjusts the flow velocity of exhaust gas to the sub-turbine by nozzle opening, and the nozzle openings of the main variable nozzle mechanism and the sub-variable nozzle mechanism. A nozzle control device that performs adjustment control, an atmospheric pressure detection device that detects the atmospheric pressure, an engine speed detection device that detects the engine speed, and an injection amount control device that controls the fuel injection amount according to the operating state. a second failure determination device for determining whether or not the failure diagnosis device has determined that either the exhaust switching valve or the intake switching valve is stuck closed; When it is determined that either the exhaust switching valve or the intake switching valve is stuck closed by means of the failure diagnosis, the valve switching control device controls the exhaust switching valve, the intake switching valve, and the intake By setting each of the bypass valves to a closed state, controlling the supercharging mode to be fixed to the single turbo mode, the nozzle control device sets the nozzle opening degree of the main variable nozzle mechanism to fully open. The injection amount control device controls the injection amount of the fuel injected according to the engine speed equal to or higher than a predetermined speed so that it becomes equal to or less than the injection amount limit value, and the atmospheric pressure decreases. A control system for an internal combustion engine that controls to decrease the injection amount limit value as the fuel injection amount increases.

According to the first aspect of the invention, the valve switching control device switches each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to a closed state or an open state, and selects a single turbo mode, a twin turbo mode, and a twin turbo mode. Either one of the switching mode and the single switching mode is set to the supercharging mode. Then, the failure diagnosis device selects the exhaust switching valve and the exhaust switching valve in accordance with the supercharging mode set by the valve switching control device based on one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor. At least one of the intake switching valve and the intake bypass valve is diagnosed for failure.

As a result, the failure diagnosis device can operate the exhaust switching valve, the intake switching valve, or the Failure diagnosis of the intake bypass valve can be performed. Therefore, without waiting until the state of the single turbo mode is reached, failure of the exhaust switching valve, the intake switching valve, or the intake bypass valve is quickly detected in the other supercharging mode, and the fail-safe process is executed. It becomes possible to avoid secondary failures such as turbo overspeed.

According to the second invention, when the supercharging mode is set to the single turbo mode, the valve switching control device controls to switch each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to the closed state. do. When it is determined that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal and the outlet pressure of the sub-compressor is higher than the atmospheric pressure, the failure diagnosis device , Diagnose that the intake switching valve is stuck open. As a result, in the single turbo mode, the fault diagnosis device can quickly detect the stuck-open failure of the intake switching valve based on the outlet pressure of the main compressor, the outlet pressure of the sub-compressor, and the atmospheric pressure.

According to the third invention, when the supercharging mode is set to the single turbo mode, the valve switching control device controls to switch each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to the closed state. do. When it is determined that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different and the outlet pressure of the sub-compressor is higher than the atmospheric pressure, the failure diagnosis device Diagnose that the exhaust switching valve is stuck open. As a result, in the single turbo mode, the fault diagnosis device can quickly detect a stuck-open failure of the exhaust switching valve based on the outlet pressure of the main compressor, the outlet pressure of the sub-compressor, and the atmospheric pressure.

According to the fourth invention, the valve switching control device keeps the intake switching valve closed and opens the exhaust switching valve and the intake bypass valve when the supercharging mode is set to the twin switching mode. Control to switch to state. When it is determined that the pressure at the outlet of the sub-compressor and the atmospheric pressure are substantially equal, the failure diagnosis device diagnoses that the exhaust switching valve is stuck closed. As a result, in the twin switching mode, the fault diagnosis device can quickly detect a stuck closed failure of the exhaust switching valve based on the outlet pressure of the sub-compressor and the atmospheric pressure.

According to the fifth invention, when the supercharging mode is set to the twin-turbo mode, the valve switching control device maintains the open state of the exhaust switching valve and opens the intake switching valve from the closed state. state, and controls the intake bypass valve to switch from the open state to the closed state. When it is determined that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different, the failure diagnosis device diagnoses that the intake switching valve is stuck closed. Thus, in the twin-turbo mode, the fault diagnosis device can quickly detect the stuck closed failure of the intake switching valve based on the outlet pressure of the main compressor and the outlet pressure of the sub-compressor.

According to the sixth invention, when the supercharging mode is set to the twin turbo mode, the valve switching control device maintains the open state of the exhaust switching valve and opens the intake switching valve from the closed state. state, and controls the intake bypass valve to switch from the open state to the closed state. Then, when it is determined that the supercharging pressure of the intake manifold is lower than the target supercharging pressure and the outlet temperature of the main compressor is equal to or higher than the first temperature threshold, the failure diagnosis device Diagnose that the bypass valve is stuck open. As a result, in the twin-turbo mode, the fault diagnosis device can quickly detect the stuck-open failure of the intake bypass valve based on the supercharging pressure of the intake manifold and the outlet temperature of the main compressor.

According to the seventh invention, when the supercharging mode is set to the single switching mode, the valve switching control device switches the exhaust switching valve and the intake switching valve to the closed state, and switches the intake bypass valve to the open state. control to switch to When it is determined that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal and the outlet pressure of the sub-compressor is higher than the atmospheric pressure, the failure diagnosis device , Diagnose that the intake switching valve is stuck open. As a result, in the single switching mode, the fault diagnosis device can quickly detect a stuck-open failure of the intake switching valve based on the outlet pressure of the main compressor, the outlet pressure of the sub-compressor, and the atmospheric pressure.

According to the eighth invention, when the supercharging mode is set to the single switching mode, the valve switching control device switches the exhaust switching valve and the intake switching valve to the closed state, and switches the intake bypass valve to the open state. control to switch to When it is determined that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different and the outlet pressure of the sub-compressor is higher than the atmospheric pressure, the failure diagnosis device Diagnose that the exhaust switching valve is stuck open. As a result, in the single switching mode, the failure diagnosis device can quickly detect a stuck-open failure of the exhaust switching valve based on the outlet pressure of the main compressor, the outlet pressure of the sub-compressor, and the atmospheric pressure.

According to the ninth invention, when the failure diagnosis device determines that any one of the exhaust switching valve, the intake switching valve, and the intake bypass valve is stuck open, the valve switching control device The switching valve and the intake switching valve are each set to the open state, the intake bypass valve is set to the closed state, and the supercharging mode is controlled to be fixed to the twin turbo mode. Further, the nozzle control device performs control so that the nozzle openings of the main variable nozzle mechanism and the sub-variable nozzle mechanism are set to fully open.

As a result, when the exhaust switching valve or the intake switching valve is stuck open, the exhaust switching valve and the intake switching valve can be set to the open state, and the intake bypass valve can be set to the closed state, During high-speed running, secondary failures such as turbo overspeed of the sub-turbocharger can be avoided. Further, when the intake bypass valve is stuck open, the exhaust switching valve, the intake switching valve, and the intake bypass valve can all be set to the open state, and the turbo overspeed of the sub turbocharger can be prevented during high-speed running. It is possible to avoid secondary failures such as

In addition, by setting the nozzle opening degree of each of the main variable nozzle mechanism and the sub variable nozzle mechanism to full open, when driving at low speed and medium load or higher (usually in single turbo mode), the sub compressor It becomes possible to lower the supercharging pressure and suppress the occurrence of surge.

According to the tenth aspect of the invention, when the failure diagnosis device determines that either the exhaust switching valve or the intake switching valve is stuck closed, the valve switching control device controls the exhaust switching valve and the intake switching valve. and intake bypass valves are closed, and the supercharging mode is controlled to be fixed to the single turbo mode. Further, the nozzle control device controls to set the nozzle opening degree of the main variable nozzle mechanism to fully open. Furthermore, the injection amount control device controls the injection amount of the fuel injected according to the engine speed equal to or higher than a predetermined speed so that it becomes equal to or less than the injection amount limit value, and the injection amount limit value increases as the atmospheric pressure decreases. control to reduce

As a result, when the exhaust switching valve or the intake switching valve is stuck closed, the exhaust switching valve, the intake switching valve, and the intake bypass valve are all set to the closed state, and the nozzle opening of the main variable nozzle mechanism is adjusted. By setting it to full open, it is possible to avoid secondary failures such as turbo overspeed of the main turbocharger at high speeds. In addition, by controlling the injection amount limit value to decrease as the atmospheric pressure decreases, even if the gauge pressure is the same as that of the flat ground, the turbo overspeed of the main turbocharger and the exhaust pressure on the inlet side of the main turbine can be prevented at high altitude. can be limited so that the pressure does not exceed the reference pressure.

1 is a diagram illustrating a schematic configuration of a control system for an internal combustion engine according to this embodiment; FIG. FIG. 4 is a diagram showing an example of an operating region map that determines operating regions in single turbo mode and twin turbo mode; FIG. 4 is a diagram showing an example of a switching valve setting map for determining the setting states of an exhaust switching valve, an intake switching valve, and an intake bypass valve in each supercharging mode; 4 is a first main flowchart showing an example of failure diagnosis processing executed by the control device according to the embodiment; 7 is a second main flowchart showing an example of failure diagnosis processing executed by the control device according to the embodiment; 9 is a third main flowchart showing an example of failure diagnosis processing executed by the control device according to the embodiment; FIG. 5 is a sub-flowchart showing an example of a sub-process of the ACV stuck-open determination process shown in FIG. 4; FIG. FIG. 5 is a sub-flowchart showing an example of a sub-process of the ECV stuck open determination process shown in FIG. 4; FIG. FIG. 5 is a sub-flowchart showing an example of a sub-process of the ECV closed sticking determination process shown in FIG. 4; FIG. FIG. 6 is a sub-flowchart showing an example of a sub-process of the ACV closed sticking determination process shown in FIG. 5; FIG. FIG. 6 is a sub-flowchart showing an example of sub-processing of the ABV stuck-open determination process shown in FIG. 5; FIG. FIG. 5 is a sub-flowchart showing an example of sub-processing of the fail-safe processing shown in FIG. 4; FIG. FIG. 13 is a sub-flowchart showing an example of sub-processing of the first fail-safe processing shown in FIG. 12; FIG. FIG. 13 is a sub-flowchart showing an example of sub-processing of the second fail-safe processing shown in FIG. 12; FIG. It is a figure which shows an example of the output limit map which determines the injection amount limit value of fuel injection amount.

MODES FOR CARRYING OUT THE INVENTION An embodiment of a control system for an internal combustion engine according to the present invention will be described in detail below with reference to the drawings. First, a schematic configuration of a control system for an internal combustion engine according to the present invention will be described with reference to FIG.

As shown in FIG. 1, an internal combustion engine control system 1 according to the present embodiment includes an air cleaner 5, an intake flow rate detection device 6, an engine (for example, a diesel engine) 10 mounted on a vehicle, and a main turbocharger 21. , a sub-turbocharger 22, a control unit (hereinafter referred to as "ECU") 80, and the like. The engine 10 is a multi-cylinder engine having a left bank 10L and a right bank 10R. A main turbocharger 21 is provided in the left bank 10L and a sub-turbocharger 22 is provided in the right bank 10R.

Further, the left bank 10L is provided with a fuel injection device 15L capable of injecting fuel directly into each cylinder according to a control signal from the ECU 80. As shown in FIG. The right bank 10R is provided with a fuel injection device 15R capable of directly injecting fuel into each cylinder according to a control signal from the ECU 80. As shown in FIG. Each member and the like will be described below while describing an intake path to the engine 10 and an exhaust path from the engine 10 .

The air cleaner 5 purifies air (intake air) obtained from the outside and supplies the air to the intake pipe 3 . The intake pipe 3 is branched into intake pipes 31L and 31R on the way. Further, an intake flow rate detection device (for example, an airflow meter) 6 for detecting the intake flow rate supplied to the intake pipe 3 before the intake pipe 3 is branched from the air cleaner 5 is arranged downstream of the air cleaner 5. It is

The downstream side of the intake pipe 31L is connected to the intake port of the main compressor 21B of the main turbocharger 21 . A discharge port of the main compressor 21B is connected to the upstream side of the intake pipe 32L. Further, the downstream side of the intake pipe 31R is connected to the intake port of the sub-compressor 22B of the sub-turbocharger 22. As shown in FIG. A discharge port of the sub-compressor 22B is connected to the upstream side of the intake pipe 32R. The downstream sides of the intake pipes 32L and 32R are connected to the upstream side of the intake pipe 33 . A third temperature detection device (for example, a temperature detection sensor) 27 for detecting the temperature of the intake air on the outlet side of the main compressor 21B, that is, the temperature at the outlet of the main compressor 21B, is provided in the intake pipe 32L near the discharge port of the main compressor 21B. is provided.

The downstream side of the intake pipe 33 is connected to the upstream side of the intake manifold 34 . The intake manifold 34 supplies intake air to each cylinder of the right bank 10R and each cylinder of the left bank 10L of the engine 10, respectively. An intercooler 38 is arranged between the intake pipe 33 and the intake manifold 34 to cool the supercharged intake air. Further, an electronic throttle valve 39 capable of adjusting the amount of intake air introduced to the intake manifold 34 is arranged downstream of the intercooler 38 between the intake pipe 33 and the intake manifold 34 . The rotational position of the electronic throttle valve 39 is continuously driven and controlled from the fully closed position to the fully opened position by a control signal from the ECU 80 .

The main compressor 21B is rotationally driven by the main turbine 21A that is rotationally driven by the exhaust gas, compresses the air sucked from the intake pipe 31L, and passes through the intake pipes 32L and 33, the intercooler 38, and the electronic throttle valve 39. Then, it is discharged to the intake manifold 34 . An intake switching valve 51 for opening and closing the intake pipe 32R is provided in the intake pipe 32R whose upstream side is connected to the discharge port of the sub-compressor 22B. The intake switching valve 51 is driven by, for example, a diaphragm actuator, and is opened and closed by a control signal from the ECU 80 .

One end of the intake bypass pipe 36 is connected to the intake pipe 32R between the discharge port of the auxiliary compressor 22B and the intake switching valve 51, that is, upstream of the intake switching valve 51, and the other end is connected to the intake pipe 32R. , is connected upstream of the intake port of the main compressor 21B of the intake pipe 31L. That is, the intake bypass pipe 36 bypasses the downstream side of the discharge port of the sub-compressor 22B and the upstream side of the intake port of the main compressor 21B. An intake bypass valve 52 for opening and closing the intake bypass pipe 36 is provided between both ends of the intake bypass pipe 36 . The intake bypass valve 52 is driven by, for example, a solenoid actuator, and is opened and closed by a control signal from the ECU 80 .

Therefore, when the intake switching valve 51 opens the intake pipe 32R and the intake bypass valve 52 closes the intake bypass pipe 36, the auxiliary compressor 22B is rotated by the auxiliary turbine 22A which is rotationally driven by the exhaust gas. It is driven, compresses the air sucked from the intake pipe 31R, and discharges it to the intake manifold 34 via the intake pipes 32R and 33, the intercooler 38, and the electronic throttle valve 39. Further, a supercharging pressure sensor 55 for detecting the supercharging pressure P5 of the intake air supplied to the intake manifold 34 is provided downstream of the electronic throttle valve 39 . A pressure sensor 23 for detecting the outlet pressure P2 of the sub-compressor 22B is provided at a position downstream of the discharge port of the sub-compressor 22B.

On the other hand, when the intake switching valve 51 closes the intake pipe 32R and the intake bypass valve 52 opens the intake bypass pipe 36, the auxiliary compressor 22B is rotated by the auxiliary turbine 22A that is rotationally driven by the exhaust gas. It is driven, compresses the air taken in from the intake pipe 31R, passes through the intake pipe 32R and the intake bypass pipe 36, and discharges it into the intake pipe 31L connected to the intake port of the main compressor 21B. In other words, intake air cannot be supplied from the auxiliary compressor 22B to the intake manifold 34 via the intake pipes 32R and 33.

An exhaust manifold 41L is connected to the exhaust side of the left bank 10L of the engine 10, and an exhaust manifold 41R is connected to the exhaust side of the right bank 10R. The upstream side of the exhaust pipe 42L is connected to the downstream side of the exhaust manifold 41L. The upstream side of an upstream main exhaust pipe 43L connected to the inlet (inlet side) of the main turbine 21A of the main turbocharger 21 is connected to the downstream side of the exhaust pipe 42L.

Further, the upstream side of the exhaust pipe 42R is connected to the downstream side of the exhaust manifold 41R. The upstream side of the upstream side sub-exhaust pipe 43R connected to the inlet (inlet side) of the sub-turbine 22A of the sub-turbocharger 22 is connected to the downstream side of the exhaust pipe 42R. One end of the communication pipe 45 is connected to the downstream side of the exhaust pipe 42L, and the other end thereof is connected to the downstream side of the exhaust pipe 42R. That is, the exhaust pipe 42L and the exhaust pipe 42R are communicated by the communication pipe 45. As shown in FIG.

Further, the engine 10 is provided with an engine speed detection device 28 and the like. The engine rotation speed detection device 28 is, for example, a rotation angle sensor capable of detecting the rotation speed of the crankshaft of the engine 10 (engine rotation speed), the rotation angle of the crankshaft (for example, the compression top dead center timing of each cylinder), and the like. is. The ECU 80 can detect the rotation speed, rotation angle, etc. of the crankshaft of the engine 10 based on the detection signal from the engine rotation speed detection device 28 .

The main turbine 21A is rotationally driven by the exhaust gas flowing in from the upstream main exhaust pipe 43L, and rotationally drives the directly connected main compressor 21B. The sub-turbine 22A is rotationally driven by the exhaust gas flowing in from the upstream side sub-exhaust pipe 43R, and rotationally drives the directly connected sub-compressor 22B. Therefore, the sub-turbocharger 22 is connected in parallel with the main turbocharger 21 .

Further, an exhaust switching valve 53 for opening and closing the upstream side sub-exhaust pipe 43R is provided in the upstream side sub-exhaust pipe 43R. The exhaust switching valve 53 is driven by, for example, a diaphragm actuator, and is opened and closed by a control signal from the ECU 80 . As a result, both the intake switching valve 51 and the exhaust switching valve 53 are opened, and when the intake bypass valve 52 is closed, the exhaust gas flows into the main turbine 21A and the auxiliary turbine 22A. As a result, the main turbocharger 21 and the sub-turbocharger 22 are activated, and the intake air is supercharged by the main compressor 21B and the sub-compressor 22B (hereinafter sometimes referred to as "twin turbo mode").

On the other hand, when the intake switching valve 51, the exhaust switching valve 53, and the intake bypass valve 52 are all closed, the exhaust gas flows into the main turbine 21A, but is prevented from flowing into the sub-turbine 22A. As a result, the main turbocharger 21 operates and the intake air is supercharged by the main compressor 21B, but the sub-turbocharger 22 does not operate and the intake air is not supercharged by the sub-compressor 22B (hereinafter referred to as "single turbocharger"). (Sometimes referred to as "turbo mode".) That is, the intake switching valve 51, the intake bypass valve 52, and the exhaust switching valve 53 are interlocked to switch between opening and closing. In FIG. 1, dotted arrows indicate the flow of intake air and exhaust gas when both the intake switching valve 51 and the exhaust switching valve 53 are open and the intake bypass valve 52 is closed.

Further, the main turbine 21A is provided with a main variable nozzle mechanism 57 that controls the flow velocity of the exhaust gas to the main turbine 21A. The main variable nozzle mechanism 57 includes a plurality of variable nozzles (VN: Variable Nozzles) 57A, an actuator 57B, and a nozzle opening sensor 57C. A plurality of variable nozzles 57A are arranged in an exhaust inflow portion around the rotation axis of the turbine wheel, and guide the exhaust gas flowing in from the upstream main exhaust pipe 43L to the turbine wheel.

The actuator 57B rotates each of the plurality of variable nozzles 57A to adjust the gap between adjacent variable nozzles 57A (in the following description, this gap is referred to as "nozzle opening"). The actuator 57B is composed of, for example, a stamping motor or the like, and adjusts the nozzle opening of the variable nozzle 57A according to a control signal from the ECU 80. By closing the variable nozzle 57A (increasing the nozzle opening), the intake supercharging pressure P increases, and by opening the variable nozzle 57A (decreasing the nozzle opening), the intake supercharging pressure P decreases. do. Also, the nozzle opening sensor 57C detects the nozzle opening of the variable nozzle 57A and outputs a detection signal to the ECU 80 .

Further, the sub-turbine 22A is provided with a sub-variable nozzle mechanism 58 that controls the flow velocity of the exhaust gas to the sub-turbine 22A. The secondary variable nozzle mechanism 58 includes a plurality of variable nozzles (VN: Variable Nozzles) 58A, an actuator 58B, and a nozzle opening sensor 58C. The multiple variable nozzles 58A have substantially the same configuration as the multiple variable nozzles 57A that constitute the main variable nozzle mechanism 57 described above. The actuator 58B and the nozzle opening sensor 58C also have substantially the same configuration as the actuator 57B and the nozzle opening sensor 57C that constitute the main variable nozzle mechanism 57 described above.

Accordingly, the plurality of variable nozzles 58A have their nozzle openings adjusted by driving the actuator 58B, thereby changing the flow velocity of the exhaust gas flowing into the sub-turbine 22A. Accordingly, by closing the variable nozzle 58A (increasing the nozzle opening), the intake supercharging pressure P rises, and by opening the variable nozzle 58A (decreasing the nozzle opening), the intake supercharging pressure P decreases.

The upstream side of the exhaust pipe 46L is connected to the discharge port (outlet side) of the main turbine 21A. Further, the upstream side of the exhaust pipe 46R is connected to the discharge port (outlet side) of the auxiliary turbine 22A. The downstream side of the exhaust pipe 46L and the downstream side of the exhaust pipe 46R are connected to the upstream side of the exhaust pipe 47 . Further, the exhaust pipe 46L is provided with a first temperature detection device (for example, a temperature detection sensor) 25 for detecting the first exhaust gas temperature on the outlet side of the main turbine 21A. Further, the exhaust pipe 46R is provided with a second temperature detection device (for example, a temperature detection sensor) 26 that detects the temperature of the second exhaust gas on the outlet side of the auxiliary turbine 22A.

The downstream side of the exhaust pipe 47 is connected to the inlet of the exhaust gas purification device 61 . Inside the exhaust gas purification device 61, an oxidation catalyst (DOC: Diesel Oxidation Catalyst) 62 and a DPF (Diesel Particulate Filter) 63 are provided from the upstream side. The oxidation catalyst 62 oxidizes and removes carbon monoxide (CO), hydrocarbons (HC), etc. contained in the exhaust gas. The DPF 63 is formed in a columnar shape or the like by a porous member made of a ceramic material or the like, and traps particulate matter (PM) by allowing the exhaust gas that flows into each small hole from the upstream side to pass through the porous material. collects the exhaust gas and allows only the exhaust gas to flow downstream. The upstream side of the exhaust pipe 48 is connected to the outflow port of the exhaust gas purification device 61 .

The ECU 80 is a known one including a CPU, EEPROM, RAM, timer, backup RAM (not shown), and the like. The CPU executes various arithmetic processes based on various programs and various parameters stored in the EEPROM. In addition, the RAM temporarily stores the results of operations performed by the CPU and the data input from each detection device, and the EEPROM and the backup RAM store data to be saved, for example, when the engine 10 is stopped. do.

The ECU 80 includes fuel injection devices 15L, 15R, pressure sensor 23, first temperature detection device 25, second temperature detection device 26, third temperature detection device (outlet temperature detection device) 27, engine speed detection device 28, intake switching. valve 51, intake bypass valve 52, exhaust switching valve 53, supercharging pressure sensor 55, actuators 57B, 58B, nozzle opening sensors 57C, 58C, accelerator pedal depression amount detector (for example, accelerator pedal depression angle sensor) 71, warning A lamp 72, an atmospheric pressure sensor 75, and the like are electrically connected.

The ECU 80 includes an intake flow rate detection device 6, a pressure sensor 23, a first temperature detection device 25, a second temperature detection device 26, a third temperature detection device 27, an engine speed detection device 28, a boost pressure sensor 55, a nozzle opening Detection signals from the degree sensors 57C and 58C, the accelerator pedal depression amount detector 71, and the atmospheric pressure sensor 75 are input. The ECU 80 can detect the flow rate of intake air drawn by the engine 10 based on the detection signal from the intake flow rate detection device 6 .

The ECU 80 can detect the supercharging pressure P5 of the intake manifold 34 based on the detection signal from the supercharging pressure sensor 55 . Based on the detection signal from the pressure sensor 23, the ECU 80 can detect the outlet pressure P2 of the sub-compressor 22B. Based on the detection signal from the first temperature detection device 25, the ECU 80 can detect the first exhaust gas temperature on the outlet side of the main turbine 21A. The ECU 80 can detect the second exhaust gas temperature on the outlet side of the auxiliary turbine 22A based on the detection signal from the second temperature detection device 26 . Based on the detection signal from the third temperature detection device 27, the ECU 80 can detect the intake air temperature (outlet temperature) T3 on the outlet side of the main compressor 21B.

The ECU 80 can detect the rotation speed, rotation angle, etc. of the crankshaft of the engine 10 based on the detection signal from the engine rotation speed detection device 28 . The engine rotation speed detection device 28 is, for example, a rotation angle sensor capable of detecting the rotation speed of the crankshaft of the engine 10, the rotation angle of the crankshaft (for example, compression top dead center timing of each cylinder), and the like. The ECU 80 can detect the nozzle openings of the plurality of variable nozzles 57A, 58A based on detection signals from the nozzle opening sensors 57C, 58C. The ECU 80 can detect the atmospheric pressure P<b>1 based on the detection signal from the atmospheric pressure sensor 75 .

The ECU 80 can detect the amount of depression of the accelerator pedal by the driver (the driver's request for acceleration or deceleration) based on the detection signal from the accelerator pedal depression amount detection device 71 . The accelerator pedal depression amount detection device 71 is, for example, an accelerator pedal depression angle sensor, and is provided on the accelerator pedal. As will be described later, the ECU 80 can turn on/off a warning lamp 72 that lights up when any one of the intake switching valve 51, the intake bypass valve 52, and the exhaust switching valve 53 is detected to be stuck open or closed. be. The warning lamp 72 is provided, for example, in the instrument panel of the vehicle.

The ECU 80 also outputs a valve opening signal for opening or closing the intake switching valve 51, the intake bypass valve 52, and the exhaust switching valve 53 according to the operating state. The ECU 80 also outputs drive signals for driving the actuators 57B and 58B based on the detection signals of the nozzle opening sensors 57C and 58C, and adjusts the nozzle opening of the plurality of variable nozzles 57A and 58A. Further, the ECU 80 outputs control signals for driving the fuel injection devices 15L and 15R based on detection signals from the engine speed detection device 28, the accelerator pedal depression amount detection device 71, etc., and directly injects fuel into each cylinder. Controls the amount of fuel injection.

Next, in the control system 1 for the internal combustion engine configured as described above, a "twin turbo mode" is a process executed by the ECU 80 in which the main turbocharger 21 and the sub-turbocharger 22 are operated to perform supercharging. , and the "single turbo mode" in which only the main turbocharger 21 operates to supercharge will be described with reference to FIGS. 2 and 3. FIG. First, the selection of the "single turbo mode" and the "twin turbo mode" will be described with reference to FIG. FIG. 2 shows an example of an operating region map that determines the operating regions of the single-turbo mode and the twin-turbo mode.

In FIG. 2, the horizontal axis indicates the engine speed, and the vertical axis indicates the required torque (fuel injection amount). A solid line 81 indicates the operating characteristic of the "single turbo mode", and a dashed line 82 indicates the operating characteristic of the "twin turbo mode". When the operating point determined by the engine speed and the required torque (fuel injection amount) is below the solid line 81, the engine 10 operates in "single turbo mode". Further, when the engine speed and the required torque increase and the operating point enters the region above the solid line 81, the engine 10 operates in "twin turbo mode". That is, when the operating point is below the switching line surrounded by the dashed line 83, the "single turbo mode" is selected, and when it is above the switching line, the "twin turbo mode" is selected.

Next, the setting states of the exhaust switching valve 53, the intake switching valve 51, and the intake bypass valve 52 set by the ECU 80 in each supercharging mode will be described based on the supercharging mode setting map 85 shown in FIG. The supercharging mode setting map 85 is stored in advance in the EEPROM, and the ECU 80 controls opening/closing of the exhaust switching valve 53, the intake switching valve 51, and the intake bypass valve 52 based on the supercharging mode setting map 85. Set the valve.

As shown in FIG. 3, when the engine 10 is operated in the "single turbo mode", the ECU 80 outputs control signals for closing the exhaust switching valve 53, the intake switching valve 51, and the intake bypass valve 52. The exhaust switching valve 53, the intake switching valve 51, and the intake bypass valve 52 are all set to the "closed state". The ECU 80 also reads out the single turbo mode flag from the RAM, sets it to "ON", and stores it in the RAM again. The ECU 80 also reads out the twin switching mode flag, the twin turbo mode flag, and the single switching mode flag from the RAM, sets them to "OFF", and stores them in the RAM again.

Further, when switching the engine 10 from the "single turbo mode" to the "twin turbo mode", the ECU 80 operates in the "twin switching mode" to the twin turbo mode for about 0.5 seconds to 1 second, and then " Operate in twin turbo mode. When operating the engine 10 in the "twin switching mode" to the twin turbo mode, the ECU 80 maintains the "closed state" of the intake switching valve 51 and opens the exhaust switching valve 53 and the intake bypass valve 52. to set the exhaust switching valve 53 and the intake bypass valve 52 to the "valve open state".

As a result, the auxiliary turbocharger 22 is operated to increase the rotation of the auxiliary turbine 22A to the rotation in the "twin turbo mode", and the intake air pressurized by the auxiliary compressor 22B flows through the intake bypass pipe 36 and the intake pipe 31L. and supplied to the inlet side of the main compressor 21B. The ECU 80 also reads out the twin switching mode flag from the RAM, sets it to "ON", and stores it in the RAM again. In addition, the ECU 80 reads the single turbo mode flag, the twin turbo mode flag, and the single switching mode flag from the RAM, sets them to "OFF", and stores them in the RAM again.

Thereafter, when operating the engine 10 in the "twin turbo mode", the ECU 80 maintains the "valve open state" of the exhaust switching valve 53 and outputs a control signal for opening the intake switching valve 51 to " At the same time, a valve closing control signal is output to the intake bypass valve 52 to set it to a "valve closed state." The ECU 80 also reads out the twin turbo mode flag from the RAM, sets it to "ON", and stores it in the RAM again. The ECU 80 also reads out the single turbo mode flag, the twin switching mode flag, and the single switching mode flag from the RAM, sets them to "OFF", and stores them in the RAM again. As a result, the intake air pressurized by the main compressor 21B and the sub-compressor 22B is supplied to the intake manifold 34 via the intake pipes 32L, 32R, 33. As shown in FIG.

Further, when switching the engine 10 from the "twin turbo mode" to the "single turbo mode", the ECU 80 operates the "single switching mode" to the single turbo mode for about 2 to 3 seconds, and then switches the engine 10 to the "single turbo mode." mode”. When the engine 10 is operated in the "single switching mode" to the single turbo mode, the ECU 80 outputs a valve closing control signal to the exhaust switching valve 53 and the intake switching valve 51 to set them to the "valve closed state". , outputs a valve opening control signal to the intake bypass valve 52 to set it to the "valve open state".

As a result, even if the exhaust switching valve 53 is in the "closed state", the sub-turbine 22A rotates due to inertia, but the intake air pressurized by the sub-compressor 22B passes through the intake bypass pipe 36 and the intake pipe 31L. It is supplied to the inlet side of the compressor 21B and is not supplied to the intake pipe 33. After that, when the rotation of the secondary turbine 22A decreases, the ECU 80 causes the engine 10 to operate in "single turbo mode". The ECU 80 also reads out the single switching mode flag from the RAM, sets it to "ON", and stores it in the RAM again. The ECU 80 also reads out the single turbo mode flag, the twin switching mode flag, and the twin turbo mode flag from the RAM, sets them to "OFF", and stores them in the RAM again.

Next, in the control system 1 for the internal combustion engine configured as described above, a failure diagnosis process is executed by the ECU 80 to perform failure diagnosis of the exhaust switching valve 53, the intake switching valve 51, and the intake bypass valve 52. will be described with reference to FIGS. 4 to 15. FIG. When the ECU 80 is activated, it activates the processes shown in FIGS. 4 to 6 at predetermined time intervals (for example, intervals of several milliseconds to several tens of milliseconds), and proceeds to step S11. 4 to 6 are stored in the EEPROM of the ECU 80 in advance.

As shown in FIG. 4, first, in step S11, the ECU 80 executes a sub-process (see FIG. 12) of the fail-safe process, which will be described later, and then proceeds to step S12. In step S12, the ECU 80 reads the single turbo mode flag from the RAM and determines whether or not it is set to "ON", that is, whether or not the engine 10 is operating in the single turbo mode. If it is determined that the single turbo mode flag is set to "ON", that is, that the engine 10 is operating in the single turbo mode (S12: YES), the ECU 80 proceeds to step S13.

In step S13, the ECU 80 executes sub-processing of "ACV stuck open determination process" for determining whether or not the intake switching valve (hereinafter also referred to as "ACV") 51 is stuck open. , the process proceeds to step S14. Here, a sub-process of the "ACV open fixation determination process" will be described with reference to FIG.

As shown in FIG. 7, first, in step S111, the ECU 80 detects the supercharging pressure P5 of the intake manifold 34 by means of the supercharging pressure sensor 55, stores it in the RAM, and then proceeds to step S112. In step S112, the ECU 80 reads the supercharging pressure P5 of the intake manifold 34 from the RAM, subtracts the pressure loss due to the intercooler 38 and the electronic throttle valve 39 from the supercharging pressure P5, and calculates the outlet pressure P3 of the main compressor 21B. After calculating and storing in the RAM, the process proceeds to step S113.

The pressure loss map storing the pressure loss due to the intercooler 38 and the electronic throttle valve 39 corresponding to the supercharging pressure P5 is obtained in advance by CAE (Computer Aided Engineering) analysis or experiment, and is stored in EEPROM in advance. ing.

In step S113, the ECU 80 detects the outlet pressure P2 of the sub-compressor 22B based on the detection signal from the pressure sensor 23, stores it in the RAM, and proceeds to step S114. In step S114, the ECU 80 detects the atmospheric pressure P1 based on the detection signal from the atmospheric pressure sensor 75, stores it in the RAM, and then proceeds to step S115. In step S115, the ECU 80 reads out the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B from the RAM, and the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are substantially equal. Determine whether or not there is

Specifically, the ECU 80 determines whether or not the absolute value of the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is equal to or less than a predetermined pressure ΔP1. The map of the predetermined pressure ΔP1 is obtained in advance by CAE (Computer Aided Engineering) analysis or experimentation, and is stored in EEPROM in advance.

When it is determined that the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are not substantially equal, that is, the absolute difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B When it is determined that the value is greater than the predetermined pressure ΔP1 (S115: NO), the ECU 80 determines that the intake switching valve (ACV) 51 is closed, terminates the sub-processing, and returns to the main flowchart. and proceed to step S14.

On the other hand, when it is determined that the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are substantially equal, the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is When determining that the absolute value is equal to or less than the predetermined pressure ΔP1 (S115: YES), the ECU 80 proceeds to step S116.

When it is determined that the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are substantially equal (S115: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is stuck open. It is also possible to determine that it is present and proceed to step S117 without executing the process of step S116.

In step S116, the ECU 80 reads the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 from the RAM, and determines whether or not the outlet pressure P2 of the sub-compressor 22B is higher than the atmospheric pressure P1. When it is determined that the outlet pressure P2 of the sub-compressor 22B is substantially equal to the atmospheric pressure P1 (S116: NO), the ECU 80 determines that the intake switching valve (ACV) 51 is closed. , the sub-process is terminated, the process returns to the main flowchart, and the process proceeds to step S14.

On the other hand, when it is determined that the outlet pressure P2 of the sub-compressor 22B is higher than the atmospheric pressure P1 (S116: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is stuck open. Then, the process proceeds to step S117. In step S117, the ECU 80 reads out the ACV open fixation flag from the EEPROM, sets it to "ON", and stores it in the EEPROM again. The ACV open fixation flag is set to "OFF" when the ECU 80 is activated and stored in the EEPROM.

As shown in FIG. 4, in step S14, the ECU 80 reads the ACV open stuck flag from the EEPROM and determines whether it is set to "ON", that is, whether the intake switching valve (ACV) 51 is stuck open. determine whether When it is determined that the ACV stuck open flag is set to "ON" (S14: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is stuck open, and performs step S15. proceed to

In step S15, the ECU 80 reads out the first fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the process. As a result, as will be described later, the ECU 80 executes the first fail-safe process when executing the failure diagnosis process after a predetermined period of time (for example, several milliseconds to several tens of milliseconds) elapses to prevent a secondary failure. It is possible to avoid this (see FIG. 12).

On the other hand, when it is determined in step S14 that the ACV open fixation flag is set to "OFF" (S14: NO), the ECU 80 determines that the intake switching valve (ACV) 51 is closed. Then, the process proceeds to step S16. In step S16, the ECU 80 executes a sub-process of "ECV open stuck determination process" for determining whether or not the exhaust switching valve (hereinafter also referred to as "ECV") 53 is stuck open. , the process proceeds to step S17. Here, the sub-processing of the "ECV open fixation determination process" will be described with reference to FIG.

As shown in FIG. 8, in steps S121 to S124, the ECU 80 executes the processes of steps S111 to S114 (see FIG. 7), and then proceeds to step S125. It should be noted that the ECU 80 may execute the processes after step S125 without executing the processes of steps S121 to S124.

In step S125, the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are read from the RAM, and whether or not the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are not equal. determine whether Specifically, the ECU 80 determines whether or not the absolute value of the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is greater than or equal to a predetermined pressure ΔP1.

The outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are substantially equal, that is, the absolute value of the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is When it is determined that the pressure is equal to or less than the predetermined pressure ΔP1 (S125: NO), the ECU 80 ends the sub-processing, returns to the main flowchart, and proceeds to step S17.

On the other hand, when it is determined that the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are not equal, that is, when the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is When determining that the absolute value is greater than the predetermined pressure ΔP1 (S125: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is closed, and proceeds to step S126.

In step S126, the ECU 80 reads the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 from the RAM, and determines whether or not the outlet pressure P2 of the sub-compressor 22B is higher than the atmospheric pressure P1. When it is determined that the outlet pressure P2 of the sub-compressor 22B is substantially equal to the atmospheric pressure P1 (S126: NO), the ECU 80 determines that the exhaust switching valve (ECV) 53 is closed. , the sub-process is terminated, the process returns to the main flowchart, and the process proceeds to step S17.

On the other hand, when it is determined that the outlet pressure P2 of the sub-compressor 22B is higher than the atmospheric pressure P1 (S126: YES), the ECU 80 determines that the exhaust switching valve (ECV) 53 is stuck open. Then, the process proceeds to step S127. In step S127, the ECU 80 reads the ECV open fixation flag from the EEPROM, sets it to "ON", and stores it in the EEPROM again. Incidentally, when the ECU 80 is activated, the ECV open stuck flag is set to "OFF" and stored in the EEPROM.

As shown in FIG. 4, in step S17, the ECU 80 reads the ECV open stuck flag from the EEPROM and determines whether it is set to "ON", that is, whether the exhaust gas switching valve (ECV) 53 is stuck open. determine whether Then, when it is determined that the ECV open fixation flag is set to "OFF" (S17: NO), the ECU 80 terminates the process.

On the other hand, when it is determined that the ECV stuck open flag is set to "ON" (S17: YES), the ECU 80 determines that the exhaust gas switching valve (ECV) 53 is stuck open, and performs step S18. proceed to In step S18, the ECU 80 reads the first fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the process. As a result, as will be described later, the ECU 80 executes the first fail-safe process when executing the failure diagnosis process after a predetermined time (for example, several milliseconds to several tens of milliseconds) has elapsed, thereby preventing a secondary failure. It is possible to avoid this (see FIG. 12).

On the other hand, when it is determined in step S12 that the single turbo mode flag is set to "OFF", that is, the engine 10 is not operating in the single turbo mode (S12: NO), the ECU 80 performs step Proceed to S19. In step S19, the ECU 80 reads out the twin switching mode flag from the RAM and determines whether or not it is set to "ON". Determines whether or not it is operating in "twin switching mode".

If it is determined that the twin switching mode flag is set to "ON", that is, the engine 10 is operating in the twin switching mode (S19: YES), the ECU 80 proceeds to step S20. In step S20, the ECU 80 executes a sub-process of "ECV stuck closed determination process" for determining whether the exhaust gas switching valve (ECV) 53 is stuck closed, and then proceeds to step S21. Here, a sub-process of the "ECV closed stuck determination process" will be described with reference to FIG.

As shown in FIG. 9, first, in step S131, the ECU 80 detects the outlet pressure P2 of the sub-compressor 22B based on the detection signal from the pressure sensor 23, stores it in the RAM, and then proceeds to step S132. In step S132, the ECU 80 detects the atmospheric pressure P1 based on the detection signal from the atmospheric pressure sensor 75, stores it in the RAM, and then proceeds to step S133. At step 133, the ECU 80 reads out the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 from the RAM, and determines whether the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 are approximately equal.

Specifically, the ECU 80 determines whether or not the absolute value of the difference between the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 is equal to or less than a predetermined pressure ΔP2. The predetermined pressure ΔP2 is obtained in advance through CAE (Computer Aided Engineering) analysis or experimentation, and is stored in the EEPROM in advance.

When it is determined that the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 are not substantially equal, that is, the absolute value of the difference between the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 is greater than the predetermined pressure ΔP2. If so (S133: NO), the ECU 80 determines that the exhaust gas switching valve (ECV) 53 is open, ends the sub-process, returns to the main flow chart, and proceeds to step S21.

On the other hand, when it is determined that the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 are substantially equal, that is, the absolute value of the difference between the outlet pressure P2 of the sub-compressor 22B and the atmospheric pressure P1 is equal to or less than the predetermined pressure ΔP2. If so (S133: YES), the ECU 80 determines that the exhaust switching valve (ECV) 53 is stuck closed, and proceeds to step S134. In step S134, the ECU 80 reads the ECV closed fixation flag from the EEPROM, sets it to "ON", and stores it in the EEPROM again. Note that the ECV closed fixation flag is set to "OFF" when the ECU 80 is activated, and is stored in the EEPROM.

As shown in FIG. 4, in step S21, the ECU 80 reads the ECV closed stuck flag from the EEPROM and determines whether it is set to "ON", that is, whether the exhaust switching valve (ECV) 53 is stuck closed. determine whether Then, when it is determined that the ECV closed sticking flag is set to "OFF" (S21: NO), the ECU 80 determines that the exhaust switching valve (ECV) 53 is in the open state. End the process.

On the other hand, when it is determined that the ECV stuck closed flag is set to "ON" (S21: YES), the ECU 80 determines that the exhaust switching valve (ECV) 53 is stuck closed, and proceeds to step S22. proceed to In step S22, the ECU 80 reads the second fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the process. As a result, as will be described later, the ECU 80 executes the second fail-safe process when executing the failure diagnosis process after a predetermined period of time (for example, several milliseconds to several tens of milliseconds) has elapsed, thereby preventing a secondary failure. It is possible to avoid this (see FIG. 12).

On the other hand, if it is determined in step S19 that the twin switching mode flag is set to "OFF", that is, if it is determined that the engine 10 is not operating in the twin switching mode (S19: NO), the ECU 80 performs step Proceed to S23.

As shown in FIG. 5, in step S23, the ECU 80 reads the twin-turbo mode flag from the RAM and determines whether or not it is set to "ON", that is, whether or not the engine 10 is operating in the twin-turbo mode. judge. When it is determined that the twin-turbo mode flag is set to "ON", ie, the engine 10 is operating in the twin-turbo mode (S23: YES), the ECU 80 proceeds to step S24.

In step S24, the ECU 80 executes sub-processing of "ACV stuck closed determination process" for determining whether or not the intake switching valve (ACV) 51 is stuck closed, and then proceeds to step S25. Here, a sub-process of the "ACV closed sticking determination process" will be described with reference to FIG.

As shown in FIG. 10, in steps S141 to S143, the ECU 80 executes the processes of steps S111 to S113 (see FIG. 7), and then proceeds to step S144. In step S144, the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are read out from the RAM, and whether or not the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are unequal. determine whether

Specifically, the ECU 80 determines whether or not the absolute value of the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is equal to or greater than a predetermined pressure ΔP3. The map of the predetermined pressure ΔP3 is obtained in advance by CAE (Computer Aided Engineering) analysis or experimentation, and is stored in EEPROM in advance.

The outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are substantially equal, that is, the absolute value of the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is When it is determined that the pressure is less than the predetermined pressure ΔP3 (S144: NO), the ECU 80 determines that the intake switching valve (ACV) 51 is open, terminates the sub-processing, and returns to the main flowchart. , the process proceeds to step S25.

On the other hand, when it is determined that the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B are not equal, that is, when the difference between the outlet pressure P3 of the main compressor 21B and the outlet pressure P2 of the sub-compressor 22B is When determining that the absolute value is equal to or greater than the predetermined pressure ΔP3 (S144: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is stuck closed, and proceeds to step S145.

In step S145, the ECU 80 reads out the ACV closed fixation flag from the EEPROM, sets it to "ON", and stores it in the EEPROM again. Note that the ACV closed fixation flag is set to "OFF" when the ECU 80 is activated, and is stored in the EEPROM.

As shown in FIG. 5, in step S25, the ECU 80 reads the ACV closed stuck flag from the EEPROM and determines whether it is set to "ON", that is, whether the intake switching valve (ACV) 51 is stuck closed. determine whether Then, when it is determined that the ACV closed stuck flag is set to "ON" (S25: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is stuck closed. proceed to

In step S26, the ECU 80 reads out the second fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the process. As a result, as will be described later, the ECU 80 executes the second fail-safe process when executing the failure diagnosis process after a predetermined period of time (for example, several milliseconds to several tens of milliseconds) has elapsed, thereby preventing a secondary failure. It is possible to avoid this (see FIG. 12).

On the other hand, if it is determined in step S25 that the ACV closed fixation flag is set to "OFF" (S25: NO), the ECU 80 determines that the intake switching valve (ACV) 51 is open. Then, the process proceeds to step S27. In step S27, the ECU 80 executes sub-processing of "ABV stuck open determination process" for determining whether or not the intake bypass valve (hereinafter also referred to as "ABV") 52 is stuck open. , the process proceeds to step S28. Here, a sub-process of the "ABV stuck open determination process" will be described with reference to FIG.

As shown in FIG. 11, in step S151, the ECU 80 executes the process of step S141 (see FIG. 10), and then proceeds to step S152. That is, in step S151, the ECU 80 detects the supercharging pressure P5 of the intake manifold 34 by means of the supercharging pressure sensor 55, stores it in the RAM, and then proceeds to step S152. In step S152, the ECU 80 detects the outlet temperature T3 of the main compressor 21B by the third temperature detection device 27, stores it in the RAM, and then proceeds to step S153.

In step S153, the ECU 80 detects the engine speed with the engine speed detector 28 and stores it in the RAM. The ECU 80 also drives the fuel injection devices 15L and 15R to calculate the fuel injection amount per unit time (actual injection amount) injected into each cylinder. Then, the ECU 80 calculates a target boost pressure P6 corresponding to the engine speed and the fuel injection amount from a target boost pressure map (not shown), and stores it in the RAM. The target supercharging pressure map stores the target supercharging pressure of the intake manifold 34 for each combination of engine speed and fuel injection amount. This target supercharging pressure map is obtained in advance by CAE (Computer Aided Engineering) analysis or experiment, and is stored in EEPROM in advance.

Subsequently, the ECU 80 reads out the boost pressure P5 of the intake manifold 34 and the target boost pressure P6 from the RAM, and determines whether the boost pressure P5 of the intake manifold 34 is lower than the target boost pressure P6. judge. When the supercharging pressure P5 of the intake manifold 34 is equal to or higher than the target supercharging pressure P6 (S153: NO), the ECU 80 terminates the sub-processing, returns to the main flowchart, and proceeds to step S28. .

On the other hand, when it is determined that the supercharging pressure P5 of the intake manifold 34 is lower than the target supercharging pressure P6 (S153: YES), the ECU 80 proceeds to step S154. In step S154, the ECU 80 reads the outlet temperature T3 of the main compressor 21B from the RAM, and determines whether or not the outlet temperature T3 of the main compressor 21B is equal to or higher than a first temperature threshold TS (for example, 190°C).

When it is determined that the outlet temperature T3 of the main compressor 21B is lower than the first temperature threshold TS (S154: NO), the ECU 80 determines that the intake bypass valve (ABV) 52 is closed. After making a determination, the sub-process is terminated, the process returns to the main flowchart, and the process proceeds to step S28. Note that the first temperature threshold TS is obtained in advance through CAE (Computer Aided Engineering) analysis or experiments, and is stored in the EEPROM in advance.

On the other hand, when it is determined that the outlet temperature T3 of the main compressor 21B is equal to or higher than the first temperature threshold TS (S154: YES), the ECU 80 determines that the intake bypass valve (ABV) 52 is stuck open. Then, the process proceeds to step S155. In step S155, the ECU 80 reads the ABV open fixation flag from the EEPROM, sets it to "ON", and stores it in the EEPROM again. Incidentally, when the ECU 80 is activated, the ABV open fixation flag is set to "OFF" and stored in the EEPROM.

As shown in FIG. 5, in step S28, the ECU 80 reads the ABV open stuck flag from the EEPROM and determines whether it is set to "ON", that is, whether the intake bypass valve (ABV) 52 is stuck open. determine whether Then, when it is determined that the ABV open fixation flag is set to "OFF" (S28: NO), the ECU 80 terminates this process.

On the other hand, when it is determined that the ABV stuck open flag is set to "ON" (S28: YES), the ECU 80 determines that the intake bypass valve (ABV) 52 is stuck open, and proceeds to step S29. proceed to In step S29, the ECU 80 reads out the first fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the process. As a result, as will be described later, the ECU 80 executes the first fail-safe process when executing the failure diagnosis process after a predetermined period of time (for example, several milliseconds to several tens of milliseconds) elapses to prevent a secondary failure. It is possible to avoid this (see FIG. 12).

On the other hand, when it is determined in step S23 that the twin-turbo mode flag is set to "OFF", that is, the engine 10 is not operating in the twin-turbo mode (S23: NO), the ECU 80 performs step Proceed to S30. In step S30, the ECU 80 reads out the single switching mode flag from the RAM and determines whether or not it is set to "ON". Determine whether or not it is operating in "single switching mode".

Then, when it is determined that the single switching mode flag is set to "OFF", that is, the engine 10 is not started (S30: NO), the ECU 80 terminates the process. On the other hand, when it is determined that the single switching mode flag is set to "ON", that is, the engine 10 is operating in the single switching mode (S30: YES), the ECU 80 proceeds to step S31. In step S31, the ECU 80 executes a sub-process of the "ACV stuck open determination process" for determining whether or not the intake switching valve (ACV) 51 is stuck open, that is, the sub-process of step S13 (FIGS. 4 and 7). ) is executed, the process proceeds to step S32.

In step S32, the ECU 80 reads out the ACV open stuck flag from the EEPROM and determines whether or not it is set to "ON", that is, whether or not the intake switching valve (ACV) 51 is stuck open. When it is determined that the ACV open stuck flag is set to "ON" (S32: YES), the ECU 80 determines that the intake switching valve (ACV) 51 is stuck open, and performs step S33. proceed to

In step S33, the ECU 80 reads the first fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the process. As a result, as will be described later, the ECU 80 executes the first fail-safe process when executing the failure diagnosis process after a predetermined period of time (for example, several milliseconds to several tens of milliseconds) elapses to prevent a secondary failure. It is possible to avoid this (see FIG. 12).

On the other hand, if it is determined in step S32 that the ACV open fixation flag is set to "OFF" (S32: NO), the ECU 80 determines that the intake switching valve (ACV) 51 is closed. Then, the process proceeds to step S34. As shown in FIG. 6, in step S34, the ECU 80 performs a sub-process of the "ECV stuck open determination process" for determining whether or not the exhaust gas switching valve (ECV) 53 is stuck open, that is, a sub-process of step S16. After executing the processing (see FIGS. 4 and 8), the process proceeds to step S35.

In step S35, the ECU 80 reads the ECV open stuck flag from the EEPROM and determines whether or not it is set to "ON", that is, whether or not the exhaust gas switching valve (ECV) 53 is stuck open. Then, when it is determined that the ECV open fixation flag is set to "OFF" (S35: NO), the ECU 80 terminates this process.

On the other hand, when it is determined that the ECV stuck open flag is set to "ON" (S35: YES), the ECU 80 determines that the exhaust gas switching valve (ECV) 53 is stuck open, and proceeds to step S36. proceed to In step S36, the ECU 80 reads the first fail-safe flag from the EEPROM, sets it to "ON", stores it in the EEPROM again, and then terminates the failure diagnosis process. As a result, as will be described later, the ECU 80 executes the first fail-safe process when executing the failure diagnosis process after a predetermined period of time (for example, several milliseconds to several tens of milliseconds) elapses to prevent a secondary failure. It is possible to avoid this (see FIG. 12).

[Fail-safe processing]
Next, sub-processing of the "fail-safe processing" executed by the ECU 80 in step S11 will be described with reference to FIGS. 12 to 15. FIG. As shown in FIG. 12, first, in step S211, the ECU 80 reads out the first fail-safe flag from the EEPROM and determines whether it is set to "ON". It is determined whether or not either the (ABV) 52 or the exhaust switching valve (ECV) 53 is stuck open.

Then, the first fail-safe flag is set to "ON", that is, one of the intake switching valve (ACV) 51, the intake bypass valve (ABV) 52, or the exhaust switching valve (ECV) 53 is If it is determined that the valve is stuck open (S211: YES), the ECU 80 proceeds to step S212. In step S212, the ECU 80 executes the sub-process of the "first fail-safe process" and then terminates the sub-process, returns to the main flow chart, and terminates the failure diagnosis process. Here, sub-processing of the "first fail-safe processing" will be described with reference to FIG.

As shown in FIG. 13, first, in step S311, the ECU 80 sets and fixes the engine 10 to operate in the "twin turbo mode", and then proceeds to step S312. Specifically, the ECU 80 outputs a valve opening control signal to the exhaust switching valve (ECV) 53 and the intake switching valve (ACV) 51 to open the exhaust switching valve 53 and the intake switching valve (ACV) 51. status” and fix it. In addition, a valve closing control signal is output to the intake bypass valve (ABV) 52 to set and fix the intake bypass valve (ABV) 52 to the "closed state".

Subsequently, in step S312, the ECU 80 fully opens the variable nozzle 57A of the main variable nozzle mechanism 57 and fully opens the variable nozzle 58A of the auxiliary variable nozzle mechanism 58, and then proceeds to step S313. 2, even if the operating point determined by the engine speed and the required torque (fuel injection amount) is the single turbo mode, the variable nozzles 57A and 58A are set to be fully open. It is possible to avoid secondary failures such as breakage and seizure due to excessive rotation of the auxiliary turbine 22A. Moreover, even if the engine 10 operates at low speed and medium load or higher, it is possible to prevent the occurrence of a surge while ensuring operating performance.

Then, in step S313, the ECU 80 turns on the warning lamp 72, displays a message such as "Please go to the service shop!" ) 51 or the intake bypass valve (ABV) 52, after which a warning notification is given to the effect that a stuck-open failure has occurred, the sub-process is terminated. As a result, the user can quickly notify the fact that any one of the exhaust switching valve (ECV) 53, the intake switching valve (ACV) 51, or the intake bypass valve (ABV) 52 is stuck open. can recognize.

On the other hand, the first fail-safe flag is set to "OFF" in step S211, that is, any of the intake switching valve (ACV) 51, the intake bypass valve (ABV) 52, and the exhaust switching valve (ECV) 53 If it is determined that the valve is not stuck open (S211: NO), the ECU 80 proceeds to step S213. In step S213, the ECU 80 reads the second fail-safe flag from the EEPROM and determines whether it is set to "ON", that is, either the intake switching valve (ACV) 51 or the exhaust switching valve (ECV) 53. is closed and fixed.

Then, when it is determined that the second fail-safe flag is set to "ON", that is, either the intake switching valve (ACV) 51 or the exhaust switching valve (ECV) 53 is stuck closed. Otherwise (S213: YES), the ECU 80 proceeds to step S214. In step S214, the ECU 80 executes the sub-process of the "second fail-safe process" and then terminates the sub-process, returns to the main flow chart, and terminates the failure diagnosis process. Here, sub-processing of the "second fail-safe processing" will be described with reference to FIGS. 14 and 15. FIG.

As shown in FIG. 14, first, in step S321, the ECU 80 sets and fixes the engine 10 to operate in the "single turbo mode", and then proceeds to step S322. Specifically, the ECU 80 outputs a valve closing control signal to the exhaust switching valve (ECV) 53, the intake switching valve (ACV) 51, and the intake bypass valve (ABV) 52, and controls the exhaust switching valve 53 and the intake switching valve. (ACV) 51 and intake bypass valve (ABV) 52 are all set to the "valve open state" and fixed.

Subsequently, in step S322, the ECU 80 fully opens the variable nozzle 57A of the main variable nozzle mechanism 57, and then proceeds to step S323. As a result, even if the operating point determined by the engine speed and the required torque (fuel injection amount) is the twin turbo mode in FIG. It is possible to avoid secondary failures such as breakage and seizure due to excessive rotation of 21A.

In step S323, the ECU 80 detects the atmospheric pressure P1 based on the detection signal from the atmospheric pressure sensor 75, stores it in the RAM, and proceeds to step S324. In step S324, the ECU 80 detects the engine speed with the engine speed detection device 28, stores it in the RAM, and then proceeds to step S325.

In step S325, the ECU 80 reads the fuel injection amount limit value corresponding to the combination of the detected atmospheric pressure P1 and the engine speed from the output control map stored in the EEPROM, and stores it in the EEPROM. Then, when the fuel injection amount injected from each of the fuel injection devices 15L and 15R exceeds the injection amount limit value, the ECU 80 sets the injection amount limit value, and then proceeds to step S326.

An example of the output control map will now be described with reference to FIG. As shown in FIG. 15, the output control map stores the fuel injection amount limit value corresponding to each combination of the engine speed on the horizontal axis and the atmospheric pressure on the vertical axis. In the output control map, the fuel injection amount limit value (mm ³ /stroke) is set so as not to increase when the engine speed is, for example, 2200 (rpm) or higher. Further, in the output control map, the lower the atmospheric pressure P1 is, the lower the fuel injection amount limit value is set.

Here, as the atmospheric pressure P1 becomes lower, that is, at high altitudes, the pressure ratio of the outlet side pressure of the main compressor 21B to the inlet side pressure of the main compressor 21B becomes higher than in the case of flat ground even if the gauge pressure is the same. For example, on flat ground, if the inlet side pressure of the main compressor 21B is 100 (kPa) and the outlet side pressure is 200 (kPa), the pressure ratio is 200/100=2. On the other hand, at high altitude, when the inlet side pressure of the main compressor 21B is 70 (kPa) and the outlet side pressure is 170 (kPa), the pressure ratio is 170/70=2.43.

As a result, by controlling the fuel injection amount limit value to decrease as the atmospheric pressure P1 decreases, even if the gauge pressure is constant, the turbo overspeed of the main turbocharger 21 and the inlet pressure of the main turbine 21A Output can be limited so that the side exhaust pressure does not exceed the reference pressure.

After that, as shown in FIG. 14, in step S326, the ECU 80 turns on the warning lamp 72, displays "Please go to the service shop!" 53 or the intake switching valve (ACV) 51 is notified that there is a stuck closed failure, and then the sub-process is terminated. As a result, the user can quickly recognize that the exhaust switching valve (ECV) 53 or the intake switching valve (ACV) 51 is stuck open.

Here, the ECU 80 includes a valve switching control device, a supercharging pressure acquisition device, a main compressor outlet pressure acquisition device, a sub-compressor outlet pressure acquisition device, a failure diagnosis device, a first determination device, a second determination device, a third determination device, fourth determination device, fifth determination device, sixth determination device, seventh determination device, eighth determination device, ninth determination device, tenth determination device, eleventh determination device, nozzle control device, first failure determination device, It functions as an example of an injection amount control device and a second failure determination device.

As described in detail above, in the internal combustion engine control system 1 according to the present embodiment, the ECU 80 selects one of four supercharging modes: the single turbo mode, the twin turbo mode, the twin switching mode, and the single switching mode. In each of the states, failure diagnosis of stuck open or stuck closed of the exhaust switching valve (ECV) 53, the intake switching valve (ACV) 51, or the intake bypass valve (ABV) 52 can be performed.

Therefore, the ECU 80 does not wait until the state of the single turbo mode is reached, and the exhaust switching valve (ECV) 53, the intake switching valve (ACV) 51, or the intake bypass valve (ABV) 52 is controlled even in other supercharging modes. It is possible to quickly detect a stuck-open or stuck-close failure, execute fail-safe processing, and avoid secondary failures such as turbo overspeed.

It should be noted that the present invention is not limited to the above embodiments, and various improvements, modifications, additions, and deletions are possible without departing from the scope of the present invention. For example, it may be as follows. In the following description, the same reference numerals as those of the engine 10 and the like according to the embodiment shown in FIGS. 1 to 15 denote the same or corresponding parts as the engine 10 and the like according to the embodiment.

(A) For example, as shown in FIG. 1, a pressure sensor 91 may be arranged on the outlet side of the main compressor 21B to detect the outlet pressure P3 of the main compressor 21B via the pressure sensor 91. . As a result, the accuracy of the outlet pressure P3 of the main compressor 21B can be improved.

(B) For example, when it is determined in step S28 that the intake bypass valve (ABV) 52 is stuck open (S28: YES), in step S29, the ECU 80 reads from the EEPROM the second fail-safe After the flag is read out, set to "ON", and stored in the EEPROM again, the processing may be terminated. As a result, when the intake bypass valve (ABV) 52 is stuck open, the second fail-safe process (see FIG. 14) is executed. Therefore, it is possible to issue a warning that the intake bypass valve (ABV) 52 is stuck open while avoiding secondary failures such as damage and seizure due to overspeeding of the main turbine 21A.

(C) Numerical values used in the description of the above embodiment are examples, and are not limited to these numerical values. Greater than (≧), less than (≦), greater than (>), less than (<), etc. may or may not include an equal sign.

1 Internal Combustion Engine Control System 10 Engine 15L, 15R Fuel Injection Device 21 Main Turbocharger 21A Main Turbine 21B Main Compressor 22 Sub Turbocharger 22A Sub Turbine 22B Sub Compressor 23 Pressure Sensor 27 Third Temperature Detector 28 Engine Speed Detector 43R Upstream side auxiliary exhaust pipe 51 Intake switching valve (ACV)
52 intake bypass valve (ABV)
53 Exhaust switching valve (ECV)
55 boost pressure sensor 57 main variable nozzle mechanism 57A, 58A variable nozzle 58 auxiliary variable nozzle mechanism 75 atmospheric pressure sensor 80 control device (ECU)

Claims (10)

a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
Equipped with an atmospheric pressure detection device that detects atmospheric pressure,
The valve switching control device is
when the supercharging mode is set to the single turbo mode, controlling each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to switch to a closed state;
The failure diagnosis device
a first determination device that determines whether the valve switching control device has set the supercharging mode to the single turbo mode;
When the first determination device determines that the valve switching control device has set the supercharging mode to the single turbo mode, the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal to each other. a second determination device for determining whether the pressure at the outlet of the sub-compressor is higher than the atmospheric pressure;
has
It is determined by the second determining device that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal and that the outlet pressure of the sub-compressor is higher than the atmospheric pressure. In this case, perform a failure diagnosis that the intake switching valve is stuck open,
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
Equipped with an atmospheric pressure detection device that detects atmospheric pressure,
The valve switching control device is
when the supercharging mode is set to the single turbo mode, controlling each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to switch to a closed state;
The failure diagnosis device
a first determination device that determines whether the valve switching control device has set the supercharging mode to the single turbo mode;
When the first determination device determines that the valve switching control device has set the supercharging mode to the single turbo mode, a pressure state in which the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different. and a third determination device that determines whether or not the outlet pressure of the sub-compressor is higher than the atmospheric pressure;
has
When the third determination device determines that the outlet pressure of the main compressor is different from the outlet pressure of the sub-compressor and that the outlet pressure of the sub-compressor is higher than the atmospheric pressure. performs a failure diagnosis that the exhaust switching valve is stuck open;
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
Equipped with an atmospheric pressure detection device that detects atmospheric pressure,
The valve switching control device is
When the supercharging mode is set to the twin switching mode, the intake switching valve is maintained in a closed state, and the exhaust switching valve and the intake bypass valve are controlled to be switched to an open state,
The failure diagnosis device
a fourth determination device that determines whether or not the valve switching control device has set the supercharging mode to the twin switching mode;
When the fourth determination device determines that the valve switching control device has set the supercharging mode to the twin switching mode, the outlet pressure of the sub-compressor and the atmospheric pressure are substantially equal to each other. A fifth determination device that determines whether or not
has
When the fifth determination device determines that the outlet pressure of the sub-compressor and the atmospheric pressure are in a substantially equal pressure state, perform a failure diagnosis that the exhaust switching valve is stuck closed.
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
with
The valve switching control device is
When the supercharging mode is set to the twin turbo mode, the open state of the exhaust switching valve is maintained, the intake switching valve is switched from the closed state to the open state, and the intake bypass valve is opened. control to switch from the valve open state to the valve closed state,
The failure diagnosis device
a sixth determination device that determines whether the valve switching control device has set the supercharging mode to the twin turbo mode;
When the sixth determination device determines that the valve switching control device has set the supercharging mode to the twin-turbo mode, a pressure state in which the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different. A seventh determination device that determines whether or not
has
When the seventh determination device determines that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are in a different pressure state, a failure diagnosis is made that the intake switching valve is stuck closed. conduct,
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
An outlet temperature detection device for detecting the outlet temperature of the main compressor,
The valve switching control device is
When the supercharging mode is set to the twin turbo mode, the open state of the exhaust switching valve is maintained, the intake switching valve is switched from the closed state to the open state, and the intake bypass valve is opened. control to switch from the valve open state to the valve closed state,
The failure diagnosis device
a sixth determination device that determines whether the valve switching control device has set the supercharging mode to the twin turbo mode;
When the sixth determination device determines that the valve switching control device has set the supercharging mode to the twin turbo mode, the supercharging pressure of the intake manifold is lower than the target supercharging pressure. and an eighth determination device that determines whether the outlet temperature of the main compressor is equal to or higher than a first temperature threshold;
has
When the eighth determination device determines that the supercharging pressure of the intake manifold is lower than the target supercharging pressure and that the outlet temperature of the main compressor is equal to or higher than the first temperature threshold, performing a failure diagnosis that the intake bypass valve is stuck open;
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
Equipped with an atmospheric pressure detection device that detects atmospheric pressure,
The valve switching control device is
When the supercharging mode is set to the single switching mode, the exhaust switching valve and the intake switching valve are switched to a closed state, and the intake bypass valve is switched to an open state,
The failure diagnosis device
a ninth determination device that determines whether the valve switching control device has set the supercharging mode to the single switching mode;
When the ninth determination device determines that the valve switching control device has set the supercharging mode to the single switching mode, the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal to each other. a tenth determination device for determining whether the pressure at the outlet of the sub-compressor is higher than the atmospheric pressure;
has
It is determined by the tenth determining device that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are substantially equal and that the outlet pressure of the sub-compressor is higher than the atmospheric pressure. In this case, perform a failure diagnosis that the intake switching valve is stuck open,
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
Equipped with an atmospheric pressure detection device that detects atmospheric pressure,
The valve switching control device is
When the supercharging mode is set to the single switching mode, the exhaust switching valve and the intake switching valve are switched to a closed state, and the intake bypass valve is switched to an open state,
The failure diagnosis device
a ninth determination device that determines whether the valve switching control device has set the supercharging mode to the single switching mode;
When the ninth determination device determines that the valve switching control device has set the supercharging mode to the single switching mode, a pressure state in which the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different. and an eleventh determination device that determines whether or not the outlet pressure of the sub-compressor is higher than the atmospheric pressure;
has
When the eleventh determining device determines that the outlet pressure of the main compressor and the outlet pressure of the sub-compressor are different and the outlet pressure of the sub-compressor is higher than the atmospheric pressure. performs a failure diagnosis that the exhaust switching valve is stuck open;
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
a main variable nozzle mechanism that adjusts the flow velocity of the exhaust gas to the main turbine of the main turbocharger by a nozzle opening;
a sub-variable nozzle mechanism that adjusts the flow velocity of the exhaust gas to the sub-turbine according to the nozzle opening;
a nozzle control device for adjusting the nozzle opening of each of the main variable nozzle mechanism and the auxiliary variable nozzle mechanism;
a first failure determination device for determining whether or not the failure diagnosis device has determined that any one of the exhaust switching valve, the intake switching valve, and the intake bypass valve is stuck open;
with
When the first failure determination device determines that any one of the exhaust switching valve, the intake switching valve, and the intake bypass valve is stuck open, the failure diagnosis is performed.
The valve switching control device sets each of the exhaust switching valve and the intake switching valve to an open state, sets the intake bypass valve to a closed state, and switches the supercharging mode to the twin turbo mode. control to fix,
The nozzle control device controls to fully open the nozzle opening of each of the main variable nozzle mechanism and the sub variable nozzle mechanism.
Control system for internal combustion engines. In the control system for an internal combustion engine according to claim 8 ,
an atmospheric pressure detection device for detecting atmospheric pressure;
an engine speed detection device that detects the engine speed;
an injection amount control device that controls the injection amount of fuel according to the operating state;
a second failure determination device for determining whether or not the failure diagnosis device has diagnosed that either the exhaust switching valve or the intake switching valve is stuck closed;
with
When the second failure determination device determines that either the exhaust switching valve or the intake switching valve is stuck closed and the failure is diagnosed,
The valve switching control device sets each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to a closed state, and controls the supercharging mode to be fixed to the single turbo mode,
The nozzle control device controls to set the nozzle opening degree of the main variable nozzle mechanism to fully open,
The injection amount control device controls an injection amount of fuel to be injected according to an engine speed equal to or higher than a predetermined speed so as to be equal to or less than an injection amount limit value, and limits the injection amount as the atmospheric pressure decreases. control to reduce the value of
Control system for internal combustion engines. a main turbocharger;
a sub-turbocharger connected in parallel to the main turbocharger;
an exhaust switching valve provided in an upstream side sub-exhaust pipe connected to an inlet side of a sub-turbine of the sub-turbocharger;
an intake switching valve provided in an intake pipe connected to the outlet side of the sub-compressor of the sub-turbocharger;
an intake bypass valve provided in an intake bypass pipe connecting an upstream side of the intake pipe from the intake switching valve and an inlet side of the main compressor of the main turbocharger;
A single turbo mode in which the exhaust switching valve, the intake switching valve, and the intake bypass valve are respectively switched to a closed state or an open state to operate only the main turbocharger for supercharging, and the main turbocharger and the sub-turbo A twin-turbo mode for supercharging by operating a charger, a twin-switching mode via which switching from the single-turbo mode to the twin-turbo mode, and a single-switching via when switching from the twin-turbo mode to the single-turbo mode a valve switching control device that controls to set to any one of the supercharging mode;
a supercharging pressure acquisition device for acquiring the supercharging pressure of the intake manifold;
a main compressor outlet pressure acquisition device for acquiring the outlet pressure of the main compressor;
a sub-compressor outlet pressure acquisition device for acquiring the outlet pressure of the sub-compressor;
Based on any one of the supercharging pressure of the intake manifold, the outlet pressure of the main compressor, and the outlet pressure of the sub-compressor, the exhaust switching valve and the a failure diagnosis device that performs failure diagnosis of at least one of the intake switching valve and the intake bypass valve;
a main variable nozzle mechanism that adjusts the flow velocity of the exhaust gas to the main turbine of the main turbocharger by a nozzle opening;
a sub-variable nozzle mechanism that adjusts the flow velocity of the exhaust gas to the sub-turbine according to the nozzle opening;
a nozzle control device for adjusting the nozzle opening of each of the main variable nozzle mechanism and the auxiliary variable nozzle mechanism;
an atmospheric pressure detection device for detecting atmospheric pressure;
an engine speed detection device that detects the engine speed;
an injection amount control device that controls the injection amount of fuel according to the operating state;
a second failure determination device for determining whether or not the failure diagnosis device has diagnosed that either the exhaust switching valve or the intake switching valve is stuck closed;
with
When the second failure determination device determines that either the exhaust switching valve or the intake switching valve is stuck closed and the failure is diagnosed,
The valve switching control device sets each of the exhaust switching valve, the intake switching valve, and the intake bypass valve to a closed state, and controls the supercharging mode to be fixed to the single turbo mode,
The nozzle control device controls to set the nozzle opening degree of the main variable nozzle mechanism to fully open,
The injection amount control device controls an injection amount of fuel to be injected according to an engine speed equal to or higher than a predetermined speed so as to be equal to or less than an injection amount limit value, and limits the injection amount as the atmospheric pressure decreases. control to reduce the value of
Control system for internal combustion engines.

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