JP2019019771A - Control device of internal combustion engine - Google Patents

Abstract

To further surely prevent the damage of an internal combustion engine possessed by an exhaust turbocharger.SOLUTION: In a control device of an internal combustion engine for controlling the internal combustion engine possessed by an exhaust turbocharger for driving a compressor which is arranged on an intake passage by using a turbine arranged on an exhaust passage, the control device performs prescribed control for suppressing boost pressure when the boost pressure of intake air circulating in the intake passage toward a cylinder exceeds a set value, performs failsafe control for preventing the damage of the internal combustion engine when a length of a time at which the boost pressure of the intake air exceeding a determination value, or the number of times exceeds a threshold, and when an ignition key or a switch is turned off after a start of the internal combustion engine after the ignition key or the switch are turned on, and the failsafe control is performed during a period of one trip until the internal combustion engine is stopped, the control device sets a threshold in a succeeding trip to a value which is lower than a threshold in a this-time trip.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for controlling an internal combustion engine accompanied by an exhaust turbocharger.

  The energy of the exhaust gas discharged from the cylinder of the internal combustion engine is used to rotate the exhaust turbine (turbine wheel), the rotation is transmitted to the compressor impeller (compressor wheel), and the intake air is pressurized and compressed (supercharging) Exhaust turbochargers that feed into cylinders are well known.

  When the pressure of the intake air flowing through the intake passage toward the cylinder, that is, the supercharging pressure, becomes excessive, there is a risk of causing damage to a portion of the internal combustion engine including the exhaust turbocharger. In order to avoid such damage, conventionally, when the boost pressure exceeds a set value, a fuel cut that temporarily interrupts the fuel injection to the cylinder is executed to avoid excessive boost pressure. (For example, see the following patent document).

  In recent internal combustion engines, the target boost pressure during operation is increased in order to improve efficiency and fuel efficiency. For this reason, the difference between the target boost pressure and the boost pressure that may damage the internal combustion engine, in other words, the safety margin is reduced. At the same time, the difference between the target boost pressure and the set value, which is the fuel cut execution condition, is also reduced.

  Therefore, in an individual whose boost pressure is likely to rise, the boost pressure frequently exceeds the set value, and there is a concern that fuel cuts are frequently repeated. The intermittent fuel cut leads to disturbance of the engine torque output from the internal combustion engine and a decrease in drivability.

  Furthermore, even if the fuel cut is executed on the condition that the supercharging pressure exceeds the set value, the possibility that the supercharging pressure increases to a level that causes a risk of damage to the internal combustion engine is eliminated. It is not possible.

Japanese Patent Laid-Open No. 08-0661104

  An object of the present invention is to more reliably prevent damage to an internal combustion engine associated with an exhaust turbocharger.

  In the present invention, an internal combustion engine attached to an exhaust turbocharger that drives a compressor disposed on an intake passage is controlled by a turbine disposed on the exhaust passage, and the intake air that flows through the intake passage toward the cylinder is controlled. When the supercharging pressure exceeds the set value, a predetermined control is performed to suppress the supercharging pressure, and the length or number of times that the supercharging pressure of the intake air exceeds the judgment value Fail-safe control is performed to prevent damage to the internal combustion engine when exceeded, and the internal combustion engine is turned off after the ignition key or switch is turned on and the internal combustion engine is started. If the fail-safe control is performed during the period of one trip until the engine is stopped, the threshold value for the next trip is set to the value for the previous trip. To constitute a control apparatus for an internal combustion engine to be set to a value lower than the threshold value.

  More specifically, as the fail-safe control, the target boost pressure is lowered from the normal time, the fuel injection amount is increased from the normal time, and the opening / closing timing of the intake valve or the exhaust valve is changed to fill the cylinder. It is preferable to perform control to reduce the air volume from the normal time or set the set value to a value lower than the normal time, and then reduce the opening of the throttle valve from the normal time.

  ADVANTAGE OF THE INVENTION According to this invention, the failure | damage of the internal combustion engine accompanying the exhaust turbo supercharger can be prevented more reliably.

The figure which shows schematic structure of the internal combustion engine for vehicles and control apparatus in one Embodiment of this invention. The figure which shows typically the relationship between the driving | operation area | region of the internal combustion engine which the control apparatus of the embodiment controls, a target supercharging pressure, a set value, and the supercharging pressure which may damage an internal combustion engine.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine of the present embodiment is a spark ignition type four-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes a spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, a compressor 51 of the exhaust turbocharger 5, an intercooler 35, an electronic throttle valve 32 that is an intake throttle valve, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream side. doing.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42, an exhaust turbine 52 of the exhaust turbocharger 5, and an exhaust purification three-way catalyst 41 are arranged on the exhaust passage 4. In addition, an exhaust bypass passage 43 that bypasses the turbine 52 and a waste gate valve 44 that is a bypass valve that opens and closes the inlet of the bypass passage 43 are provided.

  The exhaust turbocharger 5 is configured such that an exhaust turbine 52 and an impeller 51 of a compressor are coaxially connected via a shaft 53 and interlocked. Then, the turbine 52 and the impeller 51 are rotationally driven by using the energy of the exhaust gas, and the compressor is pumped with the rotational force, whereby the intake air is pressurized and compressed (supercharged) and sent to the cylinder 1.

  The waste gate valve 44 opens the bypass 43 that connects the upstream side and the downstream side of the turbine 52 in the exhaust passage 4, thereby suppressing the supercharging pressure of the intake air flowing through the intake passage 3 from becoming excessively large. Take a role. Further, feedback control for causing the supercharging pressure to follow the target supercharging pressure through the opening / closing operation of the waste gate valve 44 may be executed. The waste gate valve 44 is driven by a diaphragm type actuator 6.

  The actuator 6 has a diaphragm chamber 61 and a constant pressure chamber 62 separated by a diaphragm 60, and displaces the diaphragm 60 using a differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62. The diaphragm 60 and the waste gate valve 44 are connected via a valve rod 63. When the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 exceeds a predetermined set pressure, the diaphragm 60 and the valve rod 63 move from the diaphragm chamber 61 side toward the constant pressure chamber 62 side against the elastic biasing force of the spring 64. To displace. As a result, the waste gate valve 44 that has closed the bypass passage 43 is driven, and the bypass passage 43 is opened. On the other hand, when the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 is equal to or lower than the set pressure, the diaphragm 60 and the valve rod 63 are returned to their original positions by the elastic biasing force of the spring 64, and the waste gate valve 44 is completely And the bypass passage 43 is closed.

  Into the diaphragm chamber 61 of the actuator 6, intake pressure, that is, supercharging pressure, is introduced into a portion of the intake passage 3 downstream of the compressor 51 and upstream of the throttle valve 32. For this purpose, a supercharging pressure introduction flow path 71 for communicating the diaphragm chamber 61 and the relevant part of the intake passage 3, a depressurization flow path 72 for opening the supercharging pressure introduction flow path 71 and the diaphragm chamber 61 to the atmosphere, and a pressure An adjustment valve (vacuum switching valve) 73 for opening and closing the drainage channel 72 is provided.

  The VSV 73 is a known flow rate control valve such as a solenoid valve that receives the control signal l and changes its opening degree. If the opening degree of the VSV 73 is manipulated, a part of the supercharged air flowing from the intake passage 3 into the supercharging pressure introduction passage 71 is released to the atmosphere via the decompression passage 72, and the pressure in the diaphragm chamber 61 is increased. Can be controlled. Normally, atmospheric pressure is introduced into the constant pressure chamber 62 of the actuator 6.

  The exhaust gas recirculation device 2 realizes a so-called high-pressure loop EGR, and a predetermined portion (which may be an exhaust manifold 42) upstream of the exhaust turbine 52 in the exhaust passage 4 and an intake passage. 3, an external EGR passage 21 that communicates with an intercooler 35 and a predetermined location downstream of the throttle valve 32 (which may be a surge tank 33), an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21. An EGR valve 23 that opens and closes and controls the flow rate of the EGR gas flowing through the EGR passage 21 is used as an element.

  A variable valve timing mechanism 8 that variably controls the opening / closing timing of the intake valve of each cylinder 1 of the internal combustion engine changes the rotational phase of the camshaft that drives the intake valve with respect to the crankshaft by hydraulic pressure (lubricating oil pressure). A vane type to be driven or an electric type to be changed by an electric motor (motor drive VVT). As is well known, the camshaft is supplied with a rotational driving force from a crankshaft that is an output shaft of the internal combustion engine, and rotates following the crankshaft. A winding transmission device (not shown) for transmitting a rotational driving force is interposed between the crankshaft and the camshaft. The winding transmission device includes a crank sprocket (or pulley) provided on the crankshaft side, a cam sprocket (or pulley) provided on the camshaft side, and a timing chain (or pulley) wound around these sprockets (or pulleys). , Timing belt). The VVT mechanism 8 changes the rotational phase of the camshaft relative to the crankshaft by rotating the camshaft relative to the cam sprocket, thereby changing the opening / closing timing of the intake valve.

  Similarly, the VVT mechanism that variably controls the opening / closing timing of the exhaust valve of each cylinder 1 changes the rotation phase of the camshaft that drives the exhaust valve with respect to the crankshaft by hydraulic pressure or an electric motor. However, this VVT mechanism may not exist, and in this case, the opening / closing timing of the exhaust valve is not changed.

  An ECU (Electronic Control Unit) 0 serving as a control device for an internal combustion engine according to the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface of the ECU 0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle output from a crank angle sensor (engine rotation sensor) that detects the rotation angle of the crankshaft and the engine speed. Signal b, accelerator pedal depression amount or throttle valve 32 opening is detected as an accelerator opening (in other words, a required load factor for the internal combustion engine), and an accelerator opening signal c, a brake pedal depression amount is detected. The brake pedaling amount signal d output from the sensor that detects the intake air temperature and the intake air temperature output from the intake air pressure sensor that detects the intake air temperature and the intake pressure (supercharging pressure) in the intake passage 3 (especially the surge tank 33). An intake pressure signal e, a cooling water temperature signal f output from a water temperature sensor that detects a cooling water temperature indicating the temperature of the internal combustion engine, and intake air Mushafuto and / or a cam angle signal g output from the cam angle sensor at a plurality of cam angle of the exhaust camshaft, atmospheric pressure signal h or the like to be outputted from the atmospheric pressure sensor for detecting the atmospheric pressure is inputted.

  From the output interface of the ECU 0, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening operation for the EGR valve 23. An opening operation signal m is output to the signals 1 and VSV 73, and an intake valve and / or exhaust valve opening / closing timing control signal n is output to the VVT mechanism 8.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the amount of intake air (fresh air volume). Therefore, based on the engine speed, the intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (or Various operating parameters such as EGR gas amount), intake valve and / or exhaust valve opening / closing timing, and the like are determined. The ECU 0 applies various control signals i, j, k, l, m, and n corresponding to the operation parameters via the output interface.

  The ECU 0 of the present embodiment performs control so that the boost pressure of the intake air flowing through the intake passage 3 becomes a magnitude in the vicinity of the target boost pressure. In principle, the target boost pressure is set in accordance with the current operating range of the internal combustion engine [engine speed, accelerator opening] and the like. The ECU 0 obtains a deviation between the supercharging pressure obtained by referring to the intake pressure signal e and the target supercharging pressure, and opens and closes the VSV 73 to open and close the waste gate valve 44 in a direction to reduce the deviation. Feedback control to manipulate the degree may be executed.

  Then, the ECU 0 suppresses the boost pressure below the set value when the boost pressure of the intake air obtained by referring to the intake pressure signal e exceeds a required set value higher than the target boost pressure. Predetermined control for carrying out is performed. Specifically, a fuel cut for temporarily stopping the fuel injection from the injector 11 to the cylinder 1 is executed, or the fuel injection amount is reduced compared to the normal time when the supercharging pressure does not exceed the set value (in addition, In some cases, the opening degree of the throttle valve 32 is reduced from the normal time to reduce the amount of fresh air charged into the cylinder 1), and fuel is supplied to some of the plurality of cylinders 1 provided in the internal combustion engine. By reducing the combustion in the cylinder 1 without performing injection, the work of compression of the intake air by the exhaust turbo supercharger 5 is reduced, and thus the supercharging pressure is reduced. The set value is also set in accordance with the current operating range of the internal combustion engine. It goes without saying that this set value is set to a value lower than the supercharging pressure of a magnitude that may damage the part of the internal combustion engine including the exhaust turbocharger 5.

  However, it is not possible to completely prevent the supercharging pressure from being increased only by the above-described control. In recent internal combustion engines, the target boost pressure during operation is increased, and the difference between the target boost pressure and the boost pressure that can damage the internal combustion engine, in other words, the safety margin is reduced. . At the same time, the difference between the target boost pressure and the set value is also reduced. Therefore, even if the above-described control is performed on the condition that the supercharging pressure exceeds the set value, the supercharging pressure may increase to a level that causes a risk of damage to the internal combustion engine.

  FIG. 2 schematically illustrates the relationship between the target boost pressure, the set value, and the boost pressure that can damage the internal combustion engine. In FIG. 2, the solid line represents the target boost pressure, the broken line represents the set value, and the chain line represents the boost pressure that can damage the internal combustion engine. Further, if the boost pressure of the intake air exceeds the thick chain line, the internal combustion engine is damaged with high probability. On the other hand, even if the supercharging pressure does not exceed the thick chain line, if the state where it exceeds the thin chain line continues for a long time, the risk of damage to the internal combustion engine increases. In order to prevent damage to the internal combustion engine, it is required to reliably suppress the supercharging pressure to a level below a thin chain line.

Therefore, the ECU 0 of the present embodiment performs fail-safe control for preventing damage to the internal combustion engine when the ratio of the time during which the boost pressure of the intake air with respect to a certain time exceeds the determination value exceeds the threshold value. I am going to do that. For example, in the period of one trip from when the ignition key or switch is turned ON to start the internal combustion engine to when the ignition key or switch is turned OFF to stop the internal combustion engine, 15 seconds or more in 60 seconds If the condition that the supercharging pressure exceeds the judgment value at the rate of is established, then fail-safe control is continuously performed during the trip. The determination value referred to here may be a value equal to the set value or a value higher than the set value. Specific examples of fail-safe control content are listed below:
(I) The target supercharging pressure is reduced as compared with a normal time when fail-safe control is not performed. In particular, during the fail safe control, the VSV 73 is operated so that the opening degree of the waste gate valve 44 is increased as much as possible. Thereby, the work by the exhaust turbocharger 5 is reduced, the supercharging pressure of the intake air flowing through the intake passage 3 is reduced, and the risk of damage to the internal combustion engine including the exhaust turbocharger 5 is reduced.
(Ii) The fuel injection amount from the injector 11 is increased as compared with the normal time. The increase correction of the fuel injection amount causes a decrease in the temperature in the combustion chamber of the cylinder 1 due to the heat of vaporization (latent heat) of the fuel. As a result, the possibility of abnormal combustion such as knocking or pre-ignition in the cylinder 1 is reduced. Further, the amount of heat energy of the exhaust gas decreases, the work by the exhaust turbocharger 5 decreases, the supercharging pressure of the intake air flowing through the intake passage 3 decreases, and the internal combustion engine including the exhaust turbocharger 5 The risk of damage is reduced.
(Iii) The timing of spark ignition to the air-fuel mixture filled in the cylinder 1 by the spark plug 12 is delayed compared to the normal time. By correcting the retard of the ignition timing, the possibility of knocking in the cylinder 1 is reduced, and the risk of damage to the internal combustion engine is reduced.
(Iv) Through the operation of the intake valve timing and / or the exhaust valve timing by the VVT mechanism 8, the amount of fresh air charged in the cylinder 1 is reduced as compared with the normal time. For example, the valve opening timing or valve closing timing of the intake valve is delayed, or the valve overlap period during which both the intake valve and the exhaust valve are opened is extended. When the valve overlap amount increases, the amount of internal EGR gas that is exhaust gas remaining in the cylinder 1 without being discharged from the cylinder 1 into the exhaust passage 4 increases, and the amount of fresh air charged in the cylinder 1 decreases accordingly. The ECU 0 also decreases the fuel injection amount from the injector 11 as the fresh air amount decreases. As a result, the amount of heat energy of the exhaust gas decreases, the work by the exhaust turbocharger 5 decreases, the boost pressure of the intake air flowing through the intake passage 3 decreases, and the internal combustion engine including the exhaust turbocharger 5 Reduce the risk of damage.
(V) The set value to be compared with the supercharging pressure of the intake air, which is an execution condition for fuel cut or the like, is reduced as compared with the normal time. When the set value becomes a lower value, the boost pressure often exceeds the set value, the fuel cut execution opportunity increases, the boost pressure of the intake air flowing through the intake passage 3 decreases, and the exhaust turbo The risk of damage to the internal combustion engine including the supercharger 5 is reduced.
(Vi) After executing at least one of the above (i), (ii), (iv) or (v), the opening degree of the throttle valve 32 is reduced as compared with the normal time. The ECU 0 reduces the fuel injection amount from the injector 11 as well as the reduction of the fresh air amount filled in the cylinder 1. As a result, the amount of heat energy of the exhaust gas is reduced, the work by the exhaust turbocharger 5 is reduced, the supercharging pressure of the intake air flowing through the intake passage 3 is further reduced, and the internal combustion including the exhaust turbocharger 5 is performed. Reduces the risk of engine damage.

  The ECU 0 executes at least one of the above (i) to (vi) in the fail safe control. Note that (vi) the opening of the throttle valve 32 needs to be reduced after waiting for the supercharging pressure of the intake air flowing through the intake passage 3 toward the cylinder 1 to decrease to some extent. This is because if the throttle valve 32 is throttled in a state where the supercharging pressure is high, the pressure on the upstream side of the throttle valve 32 in the intake passage 3 becomes excessive, which may cause damage to the exhaust turbocharger 5 and the intake passage. .

  As described above, the ECU 0 continues the fail-safe control when the fail-safe control execution condition is satisfied, and thereafter during the trip, that is, until the ignition key or switch is turned OFF to stop the internal combustion engine. To do. Further, information indicating the fact that the fail-safe control execution condition is satisfied during the trip and the fail-safe control is performed is stored in the memory. This information is not erased even if the ignition key or switch is turned OFF, and is kept even after the ignition key or switch is turned ON again. On the other hand, the fail-safe control itself is terminated when the ignition key or switch is turned OFF and the trip is terminated except in the fourth stage described later, and the fail-safe control is not performed at the beginning of the next trip.

In addition, when fail-safe control is performed during the current trip, the ECU 0 of the present embodiment sets the threshold value of the fail-safe control execution condition for the next trip to a value lower than the threshold value for the current trip. . Specifically,
(First stage) In the state where information indicating that fail-safe control was performed during the previous trip was not stored in the memory, the boost pressure exceeded the judgment value at a rate of 15 seconds or more in 60 seconds. Is an implementation condition of fail-safe control. That is, the threshold value of the implementation condition in the first stage is set to “15 seconds in 60 seconds”. When the first-stage implementation condition is satisfied and the failsafe control is performed, information to that effect is stored in the memory of the ECU 0 and is referred to in the next trip.
(Second stage) In a state where information indicating that the first stage of the execution condition was established and the fail safe control was performed during the trip before the previous trip is stored in the memory, at a rate of 5 seconds or more in 60 seconds The condition that the supercharging pressure exceeds the judgment value is an execution condition for fail-safe control. That is, the threshold value of the second stage implementation condition is set to “5 seconds in 60 seconds”. This threshold value is lower than the threshold value of the first stage implementation condition. When the execution condition of the second stage is satisfied and the fail safe control is executed, information to that effect is stored in the memory of the ECU 0 and is referred to in the next trip.
(Third stage) In the state where the information that the second stage of execution conditions was satisfied and the fail safe control was performed was stored in the memory during the previous trip, the supercharging pressure is judged as the judgment value (fuel cut The execution condition of fail-safe control is that exceeding the setting value of the execution condition of (1). That is, the threshold value of the third stage implementation condition is set to “N seconds in 60 seconds (N is a slight positive number that is not 0)”. This threshold value is lower than the threshold value of the second stage implementation condition. When the execution condition of the third stage is established and the fail safe control is performed, information to that effect is stored in the memory of the ECU 0 and is referred to in the next trip.
(Fourth stage) In the state where the execution condition of the third stage was established during the trip before the previous time and the information indicating that the fail safe control was performed is stored in the memory, from the start of the trip, that is, the ignition key or The fail-safe control is performed immediately after the switch is turned ON and the internal combustion engine is started.

  In this way, when there is a history of performing fail-safe control during a past trip, ECU 0 lowers the threshold value of the fail-safe control execution condition to facilitate the fail-safe control. As a result, in an individual in which the boost pressure of the intake air is likely to increase, excessive increase of the boost pressure can be reliably suppressed and damage to the internal combustion engine can be prevented.

  The information stored in the memory by the ECU 0 and indicating that the first stage, the second stage, or the third stage during the previous trip has been established and the fail safe control has been performed is a predetermined number of times (one When failsafe control execution conditions are not satisfied over a number of trips or a plurality of consecutive trips (failsafe control is not performed), the memory may be erased.

  In the present embodiment, the turbine 52 disposed on the exhaust passage 4 controls the internal combustion engine attached to the exhaust turbocharger 5 that drives the compressor 51 disposed on the intake passage 3. When the supercharging pressure of the intake air flowing toward the cylinder 1 exceeds a set value, predetermined control such as a fuel cut for suppressing the supercharging pressure is performed, and the supercharging pressure of the intake air for a certain time When the ratio of the time when the value exceeds the judgment value exceeds the threshold value, fail-safe control is performed to prevent damage to the internal combustion engine, and the internal combustion engine is started by operating the ignition key or switch to ON. If the fail-safe control is performed during the period of one trip from when the ignition key or switch is turned OFF until the internal combustion engine is stopped, the next trip is To constitute a control apparatus 0 for an internal combustion engine for setting the threshold value to a value lower than the threshold value in the current trip in.

  According to the present embodiment, it is possible to optimize the conditions for performing fail-safe control in consideration of individual differences including deterioration over time of the internal combustion engine. Therefore, in a vehicle equipped with an individual internal combustion engine in which the boost pressure of intake air is likely to increase, even if the internal combustion engine continues to be operated at a full load (Wide Open Throttle) or a high load close thereto, the internal combustion engine is damaged. Can be reliably prevented. In addition, since the frequency of executing the fuel cut for suppressing the supercharging pressure is reduced, the engine torque is less disturbed and drivability can be kept high. As a result, it is possible to achieve both output performance and durability of the internal combustion engine.

  In addition, in the case where the supercharging pressure of the intake air accidentally exceeds the criterion value, the transition to the fourth stage described above will not be made, so fail-safe control is performed unnecessarily and the internal combustion engine Does not unduly reduce performance.

  As the fail-safe control, the ECU 0 of the present embodiment lowers the target supercharging pressure from the normal time, increases the fuel injection amount from the normal time, changes the opening / closing timing of the intake valve or the exhaust valve, and fills the cylinder 1 The fresh air amount to be reduced is reduced from the normal time, or the set value is set to a value lower than the normal time, and then the opening of the throttle valve 32 is reduced from the normal time. As a result, it is possible to avoid throttle opening of the throttle valve 32 even though the supercharging pressure of the intake air is large.

  The present invention is not limited to the embodiment described in detail above. For example, in the above-described embodiment, the fail-safe control execution condition is that the supercharging pressure of the intake air exceeds the determination value at a rate of X seconds or more in 60 seconds. Instead, fail safe control is performed when the number of times that the intake supercharging pressure exceeds the judgment value during one trip exceeds X times, and fail safe control is performed during this trip In this case, the intended purpose can be achieved even if the threshold value X of the failsafe control execution condition in the next trip is set to a value lower than the threshold value X in the current trip.

  In the internal combustion engine of the above-described embodiment, the waste gate valve 44 is driven to open and close by the diaphragm actuator 6, but an electric waste gate valve driven by an electric motor (for example, a DC servo motor) is adopted as the waste gate valve. Of course it is also possible.

  In addition, the specific mode of the VVT mechanism 8 for changing the opening / closing timing of the intake valve and / or the exhaust valve of each cylinder 1 of the internal combustion engine is also arbitrary, and is not limited uniquely. In addition to those that advance / retard the rotational phase of the intake camshaft and / or exhaust camshaft with respect to the crankshaft, multiple cams that open and drive the intake valve and / or exhaust valve are prepared and these cams are set as appropriate. Those that are used properly, those that change the lever ratio of the rocker arm via an electric motor, those that use an electromagnetic solenoid valve as a valve, and the like are known, and it is allowed to be selected from these various mechanisms.

  In addition, the specific configuration of each part can be variously modified without departing from the gist of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 3 ... Intake passage 32 ... Throttle valve 4 ... Exhaust passage 43 ... Bypass passage 44 ... Waste gate valve 5 ... Exhaust turbocharger 51 ... Compressor 52 ... Turbine 6 ... Actuator 60 ... Diaphragm 61 ... Diaphragm chamber 62 ... Constant pressure Chamber 71 ... Supercharging pressure introduction flow path 72 ... Pressure release flow path 73 ... Adjustment valve (VSV)
8 ... Variable valve timing (VVT) mechanism

Claims (2)

An internal combustion engine attached with an exhaust turbocharger for driving a compressor disposed on the intake passage by a turbine disposed on the exhaust passage;
When the supercharging pressure of the intake air flowing toward the cylinder through the intake passage exceeds a set value, a predetermined control is performed to suppress the supercharging pressure,
In addition, when the length or number of times that the supercharging pressure of the intake air exceeds the determination value exceeds the threshold value, fail safe control is performed to prevent damage to the internal combustion engine,
When the fail-safe control is performed during the period of one trip from when the ignition key or switch is turned ON to start the internal combustion engine to when the ignition key or switch is turned OFF to stop the internal combustion engine An internal combustion engine control apparatus that sets the threshold value for the next trip to a value lower than the threshold value for the current trip. As the fail-safe control,
Reduce the target boost pressure from normal, increase the fuel injection amount from normal, change the intake / exhaust valve opening / closing timing to reduce the amount of fresh air that fills the cylinder from normal, or the setting Set the value to a value lower than normal,
2. The control device for an internal combustion engine according to claim 1, wherein after that, the opening of the throttle valve is reduced more than normal.

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