Control and control methods for internal combustion engines

Abstract

A controller (40) for an internal combustion engine (10) provided with a turbocharger (20) having a turbine (202) provided in an exhaust path (15), a compressor (201) provided in an intake path (11) and rotating integrally with the turbine (202), an exhaust bypass path (30) allowing the upstream and downstream sides of the turbine (202) to communicate, a wastegate valve (31) adjusting the flow rate of exhaust gas flowing through the exhaust bypass path (30), and an electrovalve actuator (34) changing an actuating position of the wastegate valve (31), the controller (40) for the internal combustion engine (10) comprising: a driving condition detection unit (400) that detects the actuating position of the wastegate valve (31) and a true supercharging pressure, which is an actual value of a pressure of intake air compressed by the compressor (201); a supercharging state determination unit (402) that determines whether a supercharging driving state exists in which the actual supercharging pressure is higher than atmospheric pressure or is expected to become higher than atmospheric pressure, or a non-supercharging driving state exists in which the actual supercharging pressure is less than or equal to atmospheric pressure or is expected to become less than or equal to atmospheric pressure; a target opening degree calculation unit (403) that calculates a target opening degree of the wastegate valve (31); a true opening degree calculation unit (404) that calculates a true opening degree of the wastegate valve (31) based on the operating position of the wastegate valve (31); an operation amount calculation unit (405) that calculates a basic operation amount (DT1) to bring the actual opening degree close to the target opening degree; in the case of determining that a supercharging driving state exists, calculates an operation amount determined by upper-limiting a magnitude of the basic operation amount (DT1) by a preset first limit value (L1) as a final operation amount (DT2); and in the case of determining that a non-supercharging driving state exists, calculates an operation amount determined by upper-limiting the magnitude of the basic operation amount by a second limit value, which is preset to a smaller value than the first limit value, as the final operation amount; and an actuator drive unit (406) that performs drive control of the electric valve actuator (34) based on the final operation amount.

Description

BACKGROUND

[0001] This invention relates to a controller and a control method for an internal combustion engine provided with a turbocharger which adjusts the opening degree of a wastegate valve by an electromagnetic actuator.

[0002] Today, an internal combustion engine equipped with a supercharger such as a turbocharger is used in practice for the purpose of improving the engine's power output. The turbocharger compresses the intake air supplied to the internal combustion engine by rotating the turbine, utilizing the energy of the exhaust gas emitted from the internal combustion engine, and driving the compressor connected to the turbine.

[0003] In an internal combustion engine with a flange-mounted turbocharger, there is a possibility of engine damage if the pressure (hereinafter referred to as supercharging pressure) of the intake air compressed by the compressor increases excessively when the engine is running at high speed and high load. Therefore, an exhaust bypass (bypass) is usually provided in parallel with the turbine. Then, a wastegate valve is provided in the exhaust bypass path. By changing the opening degree of this wastegate valve, the flow rate of exhaust gas flowing through the exhaust bypass is adjusted. As a result, the flow rate of exhaust gas flowing into the turbine is adjusted, the driving force of the compressor changes, and the supercharging pressure is controlled.

[0004] The controller for the internal combustion engine on which the turbocharger is mounted calculates the target opening degree for realizing the desired supercharging pressure according to the driving condition of the internal combustion engine and controls the actuator so that the real opening degree of the wastegate valve, which is calculated based on the operating position of the wastegate valve detected by the position sensor, approaches the target opening degree.

[0005] However, the fully closed position of the wastegate valve deviates from the design value due to various factors, such as the mounting position deviation at the time the wastegate valve is mounted to the exhaust bypass, the output voltage shift due to the temperature characteristics of the position sensor, and the thermal expansion of the turbocharger element. Therefore, fully closed learning control has been conventionally used, which uses the output voltage of the position sensor at the time of controlling the state where the wastegate valve reaches the fully closed position (the state where the wastegate valve fully closes the exhaust bypass) as the true fully closed position. This fully closed learning control prevents deterioration of the calculation accuracy of the wastegate valve opening degree.

[0006] As a method for learning the full-closed position, for example, in JP 2015-166571 A, there is a method of learning, as the true full-closed position, the output voltage of the position sensor at the time when the operation amount of the actuator remains at the maximum value since it became the state where the wastegate valve abutted against the true full-closed position, by implementing the abutment control that makes the wastegate valve move to the closed side by feedback control until the wastegate valve abuts at the full-closed position.

[0007] DE 10 2008 051 818 A1 discloses a method for operating an internal combustion engine with a turbocharger, in which an exhaust gas flow from the internal combustion engine is at least partially bypassed past the turbine via a bypass channel for a turbine of the turbocharger. A wastegate valve is provided in the bypass channel, which is pressed against the valve seat with a second force at partial load and with a first force when the load increases. The application of the first force is limited to the time until the desired torque is reached or (as overheating protection) to a specific duration. The first force is the maximum actuating force, while the second force is sufficiently large to keep the wastegate valve closed at partial load. SUMMARY

[0008] However, according to JP 2015-166571 A, if the operating amount of the actuator is increased to the maximum value while the wastegate valve is approaching the fully closed position, the driving force of the actuator may exceed the rigidity of the connecting member that configures the link mechanism connecting the wastegate valve and the actuator, and a large bending may be caused in the connecting member.

[0009] In this way, if the fully closed position is learned in the state where the link was bent, after completing the learning of the fully closed position, when the target opening degree is set to the fully closed position or slightly open side to the fully closed position, since it is controlled to coincide with the wastegate valve opening degree with the target opening degree while bending the member, the actuator operation amount increases to the maximum or near the maximum, similarly to during the execution of the fully closed learning control.

[0010] In the learning method for the fully closed position proposed in JP 2015-166571 A, when the target opening degree is set to the fully closed position or slightly open side to the fully closed position, the operation amount of the actuator increases and causes deterioration of fuel efficiency by wasteful consumption of large power, and it is feared that, in the worst case, the motor built in the actuator overheats and breaks down due to overheating due to excessive energization.

[0011] Even if a connecting element with high rigidity is used which is not bent by the maximum driving force of the actuator, after completing the full-close learning, for example, in the state where the turbocharger element thermally expands by transition to the high-load operation of the internal combustion engine and the full-close position rises, if the target opening degree is set to the full-close position or slightly open position to the full-close position, the wastegate valve abuts against the true full-close position before the target opening degree is reached. Also in this case, in order to coincide the wastegate valve with the target opening degree by feedback control, the actuator operation amount increases to the maximum or near the maximum, it causes deterioration of fuel efficiency by wastefully consuming large power, and it is feared that in the worst case,the actuator built into the engine overheats and breaks due to overheating caused by excessive energization.

[0012] Regarding the concern of JP 2015-166571 A described above, as disclosed in JP 6038271 B, for example, there is a countermeasure to limit the maximum value of the actuator operation amount by the limit value, which is set in advance as the operation amount that does not damage the actuator even if the actuator energization continues for more than a predetermined period when the opening degree of the wastegate valve is below the predetermined value. Accordingly, even if the actuator operation amount becomes excessive because the wastegate valve abuts the true fully closed position before reaching the target opening degree, the motor built into the actuator can be prevented from overheating and breaking down.

[0013] However, in order to control the wastegate valve to the fully closed position, since it is necessary to prevent the closing failure caused by the back pressure of the exhaust gas, it is necessary to push the wastegate valve to the fully closed position by an actuator driving force that can withstand the maximum exhaust gas pressure. Therefore, as the limit value of the actuator operating amount in JP 6038271 B, even under the driving condition where the exhaust gas pressure is at its maximum, it is necessary to set the operating amount that can generate the actuator driving force that can surely push the wastegate valve to the fully closed position and maintain the fully closed position.

[0014] As mentioned above in JP 2015-166571 A, since the learning of the fully closed position is performed in the state where the actuator operation amount is stuck at the maximum value, after completing the learning of the fully closed position, if the target opening degree is set to the fully closed position or a slightly open side to the fully closed position, the actuator operation amount increases to or near the maximum, causing a deterioration in fuel efficiency due to wasteful consumption of large power, and there is a concern that, in the worst case, the motor built into the actuator may overheat and break down due to overheating caused by excessive excitation. These are problems.

[0015] In JP 6 038 271 B1, although the motor incorporated in the actuator can be prevented from overheating due to excessive excitation even under driving conditions where the exhaust gas pressure becomes maximum, it is necessary to set as the limit value the operating amount that can generate the actuator driving force that can securely press the wastegate valve to the fully closed position and maintain the fully closed state. Therefore, even in the light-load operating region where the exhaust gas pressure is relatively low, if the target opening degree is set near the fully closed position, the actuator operating amount becomes unnecessarily large compared to the opposing exhaust gas pressure, causing deterioration of fuel efficiency by wastefully consuming large power. This remains a problem.

[0016] The present invention has been implemented to solve the above problem. An object of the invention is to provide a controller and control method for an internal combustion engine that can protect the actuator-mounted motor from overheating when the wastegate valve is controlled close to the fully closed position or the fully closed position, and prevent fuel efficiency deterioration caused by wasteful consumption of large power, even in the light-load operating region where the exhaust gas pressure is relatively low.

[0017] This object is achieved by a control system for an internal combustion engine according to patent claim 1. Advantageous embodiments of the control system are set forth in the subclaims. The object is further achieved by a control method for an internal combustion engine according to patent claim 7.

[0018] According to the controller and the control method for the internal combustion engine concerning the present invention, in a case where the wastegate valve may abut against the fully closed position or the fully opened position and the magnitude of the basic operation amount of the electric valve actuator may become excessively large due to erroneous setting or erroneous learning of the fully closed position or the fully opened position of the wastegate valve, since the magnitude of the basic operation amount is upper-limited by the first limit value or the second limit value, the power consumption of the electric valve actuator is reduced, deterioration of fuel efficiency can be reduced, and overheating of the electric valve actuator can be reduced.

[0019] Since the exhaust gas flow rate increases in the supercharged driving state and the exhaust gas pressure becomes high compared to the non-supercharged driving state, the amount of operation of the solenoid valve actuator for maintaining the wastegate valve at a certain opening degree against the exhaust gas pressure becomes large. On the other hand, since the exhaust gas pressure becomes low in the non-supercharged driving state compared to the supercharged driving state, the amount of operation of the solenoid valve actuator for maintaining the wastegate valve at a certain opening degree becomes small. Since the second limit value of the non-supercharged driving state is set to a value smaller than the first limit value of the supercharged driving state, the power consumption of the non-supercharged driving state, in which the amount of operation required becomes small, is further reduced compared to the supercharged driving state.In normal operation, as the frequency of the non-supercharge driving state becomes high, the reduction effect of power consumption becomes large. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic configuration diagram of the internal combustion engine and the controller according to Embodiment 1 of the present invention; Fig. 2 is a block diagram of the controller according to Embodiment 1 of the present invention; Fig. 3 is a hardware configuration diagram of the controller according to Embodiment 1 of the present invention; Fig. 4 is a schematic diagram of the drive mechanism of the wastegate valve according to Embodiment 1 of the present invention; Fig. 5 is a characteristic figure for explaining the supercharge driving state and the non-supercharge driving state according to Embodiment 1 of the present invention; Fig. 6 is a characteristic figure of the opening degree of the wastegate valve according to Embodiment 1 of the present invention; Fig. 7 is a characteristic figure of the driving force of the electric motor according to Embodiment 1 of the present invention; Fig. 8 is a timing chart for explaining the behavior of the operation amount limit processing according to Embodiment 1 of the present invention; Fig. 9 is a flowchart for explaining the processing of the control according to Embodiment 1 of the present invention; Fig. 10 is a flowchart for explaining the processing of the control according to Embodiment 2 of the present invention; and Fig. 11 is a flowchart for explaining the processing of the control according to Embodiment 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiment 1

[0020] Fig. 1 is a configuration diagram showing an entire system to which a controller 40 of the internal combustion engine 10 (hereinafter simply referred to as controller 40) according to Embodiment 1 of the present invention is applied. The internal combustion engine 10 has a cylinder 5 in which the fuel-air mixture is combusted. The internal combustion engine 10 is provided with an intake path 11 that supplies air to the cylinder 5. An air cleaner 12 is mounted at an inlet of the intake path 11 of the internal combustion engine 10. An air flow sensor 41 for detecting an intake air amount is provided in the part of the intake path 11 on the downstream side of the air cleaner 12. A compressor 201 of a turbocharger 20 is provided in a part of the intake path 11 on the downstream side of the air flow sensor 41.The compressor 201 and a turbine 202 of the turbocharger 20 are connected by a connecting shaft 203, and the compressor 201 is rotated by energy from the exhaust gas input to the turbine 202. An intercooler 13 for cooling the compressed air is provided in the part of the intake path 11 on the further downstream side of the compressor 201. A throttle valve 14 is provided in the part of the intake path 11 on the further downstream side of the intercooler 13. A supercharge pressure sensor 42, which outputs an electrical signal according to a supercharge pressure, which is a pressure of the intake air compressed by the compressor 201, is provided between the intercooler 13 and the throttle valves 14. The part of the intake path 11 on the downstream side of the throttle valve 14 is an intake manifold that distributes the intake air to the cylinders 5.

[0021] The internal combustion engine 10 is connected to an exhaust path 15 that discharges the exhaust gas combusted in the cylinder 5. The turbine 202 of the turbocharger 20, mentioned above, is provided in the center of the exhaust path 15. The exhaust gas purification catalyst 16 for purifying the exhaust gas is provided in the part of the exhaust path 15 on the downstream side of the turbine 202. An exhaust gas bypass 30, which bypasses the turbine 202 and connects the intake and exhaust sides of the turbine 202, is provided in the exhaust path 15. A wastegate valve 31 as an exhaust gas bypass valve that adjusts a flow rate of the exhaust gas flowing through the exhaust gas bypass 30 is provided in the exhaust gas bypass 30. An electric valve actuator 34, which is an electric actuator that changes the operating position of the wastegate valve 31, and a valve position sensor 43, which outputs an electric signal based on the operating position of the wastegate valve 31, are provided.

[0022] The wastegate valve 31 and the solenoid valve actuator 34 are mechanically connected to a link mechanism 32. In the present embodiment, as shown in Fig. As shown in Figure 4, the link mechanism 32 is a link mechanism that converts linear motion of an output shaft 33 of the electric valve actuator 34 into rotational motion that opens and closes the wastegate valve 31. The link mechanism 32 is provided with a valve rotation shaft 32a that rotates the wastegate valve 31, and an arm 32b that extends outward in a radial direction from the valve rotation shaft 32a and rotates integrally with the valve rotation shaft 32a. The end of the arm 32b and the end of the output shaft 33 of the electric valve actuator 34 are pivotally connected to each other by a pin and the like. Accordingly, when the output shaft 33 of the electric valve actuator 34 moves to one side of the axial direction, the wastegate valve 31 closes.When the output shaft 33 of the solenoid valve actuator 34 moves to the other side of the axial direction, the wastegate valve 31 opens; and the opening degree of the wastegate valve 31 changes according to the moving position of the output shaft 33 of the solenoid valve actuator 34.

[0023] The electric valve actuator 34 is provided with an electric motor that generates a normal rotation or reverse rotation of the rotational driving force and a magnitude of the rotational driving force controlled by the controller 40, a conversion mechanism that converts the rotational motion of the electric motor into linear motion, and an output shaft 33 that moves linearly to one side or the other in the axial direction through the conversion mechanism. A feed screw mechanism, a rack and pinion mechanism, or the like is used as the conversion mechanism. The output shaft 33 is a rod-shaped member that is longer than the arm 32b of the link mechanism 32 and the like, for reducing heat transferred from the housing of the turbine 202 to the electric valve actuator 34 and restricting installation space.The valve position sensor 43 detects the movement position in the axial direction of the output shaft 33 of the electric valve actuator 34. The valve position sensor 43 is built into the electric valve actuator 34 or is arranged near the electric valve actuator 34.

[0024] The electric motor of the electric valve actuator 34 is a DC motor. The magnitude of the rotational driving force generated by the electric motor and the direction of normal rotation or reverse rotation of the driving force change according to the magnitude of the current supplied to the electric motor and the direction of the current supply.

[0025] The controller 40 is also one whose control subject is the internal combustion engine 10. As in Fig. 2, the controller 40 is provided with control units such as a driving condition detection unit 400, a target supercharging pressure calculation unit 401, a supercharging state determination unit 402, a target opening degree calculation unit 403, a real opening degree calculation unit 404, an operation amount calculation unit 405, and an actuator drive unit 406. The respective control units 400 to 406 and the like of the controller 40 are realized by processing circuits included in the controller 40. Specifically, as shown in Fig. 3, the controller 40 includes, as a processing unit, an arithmetic processing unit (computer) 90 such as a CPU (central processing unit), storage devices 91 that exchange data with the arithmetic processing unit 90, an input circuit 92 that inputs external signals to the arithmetic processing unit 90, an output circuit 93 that outputs signals from the arithmetic processing unit 90 to the outside, and the like.

[0026] As the arithmetic processing unit 90, ASIC (Application Specific Integrated Circuit), IC (Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), various types of logic circuits, various types of signal processing circuits, and the like can be provided. As the arithmetic processing unit 90, a plurality of the same type or different types can be provided, and each processing can be shared and executed. As the storage devices 91, a RAM (Random Access Memory) that can read and write data from the arithmetic processing unit 90, a ROM (Read Only Memory) that can read data from the arithmetic processing unit 90, and the like are provided.The input circuit 92 is connected to various types of sensors and switches and is provided with an A / D converter and the like for inputting output signals from the sensors and switches to the arithmetic processing unit 90. The output circuit 93 is connected to electrical loads and is provided with a drive circuit and the like for outputting a control signal from the arithmetic processing unit 90.

[0027] In addition, the arithmetic processing unit 90 runs software elements (programs) stored in the storage device 91, such as a ROM, and collaborates with other hardware devices in the controller 40, such as the storage device 91, the input circuit 92, and the output circuit 93, so that the respective functions of the control units 400 to 406 included in the controller 40 are realized. Setting data items, such as characteristic data and determination values, to be used in the control units 400 to 406 are stored as part of software elements (programs) in the storage device 91, such as a ROM.

[0028] In the present embodiment, the input circuit 92 is connected to various types of sensors, such as the air flow sensor 41, the supercharging pressure sensor 42, the valve position sensor 43, a crank angle sensor that detects a rotation angle of the crankshaft of the internal combustion engine 10, a throttle position sensor that detects an opening degree of the throttle valve 14, and an atmospheric pressure sensor that detects atmospheric pressure. The output circuit 93 is connected to various types of actuators, such as the solenoid valve actuator 34, an injector, and an ignition coil.Then, the controller 40 controls the pressure of the intake air compressed by the compressor 201 to a desired supercharging pressure by driving various types of actuators mentioned above based on various types of input information mentioned above, and also controls the combustion state and output torque of the internal combustion engine 10 appropriately. <Antriebsbedingungs-Detektionseinheit 400>

[0029] The driving condition detection unit 400 implements driving condition detection processing that detects the driving condition of the internal combustion engine 10 and the vehicle. The driving condition detection unit 400 detects various types of driving conditions based on the output signals of various types of sensors and the like. In the present embodiment, the driving condition detection unit 400 detects an actuating position of the wastegate valve 31 and a true supercharging pressure, which is an actual value of the pressure of the intake air compressed by the compressor 201. The driving condition detection unit 400 detects the actuating position of the wastegate valve 31 based on the output signal of the valve position sensor 43. The driving condition detection unit 400 detects a true supercharging pressure based on the output signal of the supercharging pressure sensor 42. <Soll-Superladungsdruck-Recheneinheit 401>

[0030] The target supercharging pressure calculation unit 401 implements a target supercharging pressure calculation process that calculates a target supercharging pressure, which is a target value of the supercharging pressure. In the present embodiment, the target supercharging pressure calculation unit 401 calculates the target supercharging pressure based on the driving condition of the internal combustion engine 10, such as the rotational speed of the internal combustion engine 10, and the cylinder intake air amount. <Superladungszustands-Bestimmungseinheit 402>

[0031] The supercharging state determination unit 402 implements supercharging state determination processing that determines whether there is a supercharging driving state in which the actual supercharging pressure is higher than or expected to become higher than the atmospheric pressure, or a non-supercharging driving state in which the actual supercharging pressure is less than or equal to or expected to become less than or equal to the atmospheric pressure.In the present embodiment, in the case where the actual supercharging pressure detected by the supercharging pressure sensor 42 is higher than atmospheric pressure, the supercharging state determination unit 402 determines that a supercharging driving state exists, and in the case where the actual supercharging pressure detected by the supercharging pressure sensor 42 is less than or equal to atmospheric pressure, the supercharging state determination unit 402 determines that a non-supercharging driving state exists. Alternatively, in the case where the target supercharging pressure is higher than atmospheric pressure, the supercharging state determination unit 402 may determine that a supercharging driving state exists; and in the case where the target supercharging pressure is less than or equal to the atmospheric pressure, the supercharging state determining unit 402 may determine that a non-supercharging driving state exists.In the present embodiment, since the supercharging pressure is the pressure on the upstream side of the throttle valve 14, in the non-supercharging driving state, the supercharging pressure becomes equal to the atmospheric pressure or becomes slightly lower than the atmospheric pressure by a pressure loss of the intake path 11, the air cleaner 12, the compressor 201 and the like.

[0032] Fig. 5 shows a relationship between the rotational speed and load of the internal combustion engine 10 and the supercharging driving state and the non-supercharging driving state. As a result, when the pressure in the intake manifold increases to an opening of the throttle valve 14, the cylinder intake air quantity increases, the amount of fuel corresponding to the cylinder intake air quantity is injected and supplied, and the loads due to compression, ignition, and combustion increase. For example, when the throttle valve 14 is gradually opened from fully closed to fully open, the pressure in the intake manifold will also rise and the load will also become high. Then, after a while, the pressure in the intake manifold reaches atmospheric pressure. In this way, when the pressure in the intake manifold is less than or equal to atmospheric pressure, it is in a non-supercharging driving state.In the internal combustion engine 10 equipped with the turbocharger 20, when the compressor 201 is driven, the intake air is compressed, and the pressure in the intake manifold rises sooner than atmospheric pressure, then it is the supercharged driving state. Because the cylinder intake air quantity in the supercharged driving state becomes relatively larger than that in the non-supercharged driving state, and the pressure of the exhaust gas discharged from the internal combustion engine 10 in the supercharged driving state also becomes relatively higher than that in the non-supercharged driving state. <Soll-Öffnungsgrad-Recheneinheit 403>

[0033] The target opening degree calculation unit 403 implements target opening degree calculation processing that calculates a target opening degree of the wastegate valve 31. In the present embodiment, the target opening degree calculation unit 403 calculates the target opening degree based on the driving condition of the internal combustion engine 10, such as the target supercharging pressure, the actual supercharging pressure, and the supercharging state determination result of the supercharging driving state or the non-supercharging driving state. If it is determined to be in the supercharging driving state, the target opening degree calculation unit 403 calculates the opening degree of the wastegate valve 31 to bring the actual supercharging pressure close to the target supercharging pressure as the target opening degree.For example, the target opening degree calculation unit 403 calculates the target opening degree through feedback control based on the difference between the target supercharging pressure and the actual supercharging pressure. When the actual supercharging pressure increases, the target opening degree is decreased, and when the actual supercharging pressure decreases, the target opening degree is increased. In the supercharging drive state, the target opening degree is set to the fully closed opening degree or the opening degree larger than the fully closed opening degree.

[0034] If it is determined that a non-supercharging driving state exists, the target opening degree calculation unit 403 calculates the opening degree of the wastegate valve 31, which is preset for each driving condition of the engine 10, such as the rotational speed and load of the engine 10, as the target opening degree. In the non-supercharging driving state, fundamentally, in order to reduce the exhaust gas pressure on the upstream side of the turbine 202 and improve fuel efficiency by reducing pumping loss, the target opening degree is set to a larger opening degree than the fully closed opening degree, and the wastegate valve 31 is opened.

[0035] However, even in the non-supercharging driving state, depending on the driving condition of the internal combustion engine 10, the target opening degree is set to the fully closed opening degree. For example, in order to reduce vibration of the exhaust path 15 due to resonance between exhaust pulsation and the exhaust path 15, the target opening degree is set to the fully closed opening degree in a predetermined driving condition, such as a low-speed region. By fully closing the wastegate valve 31, the exhaust pulsation of the cylinder 5, which becomes a frequency corresponding to the rotational speed, is no longer transmitted to the exhaust path 15 on the downstream side of the turbine 202 via the exhaust bypass 30, the resonance frequency increases, and the occurrence of resonance can be suppressed.In the driving condition expected to transition to the supercharging driving state, the target opening degree is set to the fully closed state in advance, so that at the time of transition to the supercharging driving state, a time delay until the wastegate valve 31 is fully closed does not occur. For example, when the accelerator pedal opening degree increases even in the non-supercharging driving state, the target opening degree is set to the fully closed opening degree. <Echtöffnungsgrad-Recheneinheit 404>

[0036] The real opening degree calculation unit 404 implements a real opening degree calculation processing that calculates a real opening degree of the wastegate valve 31 based on the operating position of the wastegate valve 31 detected by the driving condition detection unit 400.

[0037] Fig. 6 is a characteristic diagram in which a vertical axis shows the output voltage Vs of the valve position sensor 43, which is detected as the operating position of the wastegate valve 31, and a horizontal axis shows a true opening degree of the wastegate valve 31. Using Equation (1), the true opening degree calculation unit 404 calculates the true opening degree of the wastegate valve 31 based on the output voltage Vs (hereinafter also referred to as the operating position Vs) of the valve position sensor 43 and the output voltage Vmin of the fully closed position (hereinafter also referred to as the fully closed position Vmin). Here, Vrng is a variation width of the output voltage Vs at the time of changing from the fully closed position to the fully open position. Real opening degree [%]=(Vs−Vmin) / Vrng×100

[0038] Although the output voltage Vmin of the fully closed position may be a preset value, the output voltage Vmin is a learning value in the present embodiment. A fully closed position deviates from a design value due to various factors, such as a deviation in the mounting position at the time of mounting the wastegate valve 31 to the exhaust bypass 30, a drift in the output voltage due to a temperature characteristic of the valve position sensor 43, and thermal expansion of the turbocharger element.

[0039] Accordingly, the true opening degree calculation unit 404 learns the operating position Vs of the wastegate valve 31 at the time of determining that the wastegate valve 31 is in the fully closed state as the fully closed position Vmin; and calculates the true opening degree based on the operating position of the wastegate valve 31 based on the learned fully closed position Vmin. According to this configuration, the operating position Vs of the wastegate valve 31 at the time of pushing the wastegate valve 31 to the fully closed position and controlling it to the fully closed state is learned as the true fully closed position Vmin; and by calculating the true opening degree based on the learned fully closed position Vmin, the calculation accuracy of the true opening degree can be improved. <Aktuator-Antriebseinheit 406>

[0040] The actuator drive unit 406 implements valve drive processing that performs drive control of the electric valve actuator 34 based on the final operation amount DT2 calculated by the operation amount calculation unit 405 described below.

[0041] In the present embodiment, as mentioned above, the electric valve actuator 34 is provided with the electric motor (in this example, a DC motor), and the actuator drive unit 406 supplies a drive current corresponding to the final operating amount DT2 to the electric valve actuator 34. Accordingly, the electric valve actuator 34 is driven, the operating position of the wastegate valve 31 changes, and the true opening degree of the wastegate valve 31 changes.

[0042] The operating amount of the solenoid valve actuator 34 is a parameter that determines the energizing direction and the magnitude of the energizing current of the alternating current, for example, a PWM signal (duty signal from -100 [%] to +100 [%]). Fig. 7 is a characteristic diagram showing the relationship between the operating amount of the solenoid valve actuator 34 and the driving force generated by the DC motor. When the PWM signal, which is the operating amount, is 0 [%], the motor current becomes 0, and the driving force generated by the DC motor also becomes 0. Then, at the time of 0 [%] < PWM signal <= 100 [%], the current for normal rotation according to the magnitude (absolute value) of the PWM signal flows to the DC motor, and the output shaft 33 is pushed out of the solenoid valve actuator 34. Accordingly, the wastegate valve 31 moves to the open side. At the time of -100% <= PWM signal < 0 [%], the current for reverse rotation according to the magnitude (absolute value) of the PWM signal flows to the DC motor, and the output shaft 33 is pulled inside the solenoid valve actuator 34. Accordingly, the wastegate valve 31 moves to the closed side.In this way, the driving force of the electric valve actuator 34 changes according to the operation amount of the electric valve actuator 34. <Betriebsbetrags-Recheneinheit 405>

[0043] The operation amount calculation unit 405 is provided with a basic operation amount calculation unit 405A and a final operation amount calculation unit 405B, which implement operation amount calculation processing that calculates the operation amount of the solenoid valve actuator 34. The basic operation amount calculation unit 405A implements basic operation amount calculation processing that calculates a basic operation amount DT1 to bring the actual opening degree close to the target opening degree. In the present embodiment, the basic operation amount calculation unit 405A calculates the basic operation amount DT1 through feedback control, such as PID control, based on the difference between the target opening degree and the actual opening degree. The basic operation amount calculation unit 405A changes the basic operation amount DT1 within a settable range of the operation amount (in this example, within a range of -100 [%] to +100 [%]).

[0044] The final operation amount calculation unit 405B implements operation amount limiting processing that, in the case of determining that the supercharging driving state exists, calculates an operation amount obtained by performing an upper limit on the magnitude (absolute value) of the basic operation amount DT1 by a preset first limit value L1 as the final operation amount DT2; and, in the case of determining that the non-supercharging driving state exists, calculates an operation amount obtained by performing an upper limit on the magnitude (absolute value) of the basic operation amount DT1 by a second limit value L2 preset to a value smaller than the first limit value L1 as the final operation amount DT2.

[0045] At the time of controlling the wastegate valve 31 to the fully closed opening degree or the fully open opening degree, due to incorrect setting or incorrect learning of the fully closed position or the fully open position, the wastegate valve 31 may abut the fully closed position or the fully open position, and the magnitude of the basic operation amount DT1 of the electric valve actuator 34 may become excessive. Even in this case, since the magnitude of the basic operation amount DT1 is limited by the first limit value L1 or the second limit value L2 above, the power consumption of the electric valve actuator 34 is reduced, and deterioration in fuel efficiency and overheating of the electric valve actuator 34 can be reduced.

[0046] Since in the supercharged driving state, the flow rate of the exhaust gas increases and the pressure of the exhaust gas becomes high compared with the non-supercharged driving state, the magnitude of the operation amount of the solenoid valve actuator 34 for maintaining the solenoid valve actuator 34 at a certain opening degree against the pressure of the exhaust gas becomes large.

[0047] On the other hand, since the exhaust gas pressure becomes low in the non-supercharging driving state compared to the supercharging driving state, the magnitude of the operation amount of the solenoid valve actuator 34 for maintaining the wastegate valve 31 at a certain opening degree becomes small. Since the second limit value L2 of the non-supercharging driving state is set to a smaller value than the first limit value L1 of the supercharging driving state, the power consumption of the non-supercharging driving state, in which the required operation amount becomes small, is further reduced compared to the supercharging driving state. Therefore, even in cases where the magnitude of the basic operation amount DT1 becomes excessive according to the supercharging driving state and the non-supercharging driving state, the power consumption can be appropriately reduced.

[0048] Specifically, as shown in Equation (2), in the case of determining that the supercharge driving state exists, when the base operation amount DT1 is smaller than the negative first limit value (-L1), the final operation amount calculation unit 405B sets the negative first limit value (-L1) to the final operation amount DT2; when the base operation amount DT1 is greater than the positive first limit value (+L1), the final operation amount calculation unit 405B sets the positive first limit value (+L1) to the final operation amount DT2; and when the base operation amount DT1 is within a range from the negative first limit value (-L1) to the positive first limit value (+L1), the final operation amount calculation unit 405B sets the base operation amount DT1 to the final operation amount DT2. The first limit value L1 itself is a positive value (L1>0). A) In the case of the supercharged propulsion state 1) At the time of DT1 < -L1 DT2=−L1 2) At the time of DT1 > +L1 DT2=+L1 3) At the time of -L1 <= DT1 <= +L1 DT2=DT1

[0049] As shown in equation (3), in the case of determining that a non-supercharge driving state exists, when the base operation amount DT1 is smaller than the negative second limit value (-L2), the final operation amount calculation unit 405B sets the negative second limit value (-L2) to the final operation amount DT2. When the base operation amount DT1 is greater than the positive second limit value (+L2), the final operation amount calculation unit 405B sets the positive second limit value (+L2) to the final operation amount DT2. When the base operation amount DT1 is within the range from the negative second limit value (-L2) to the positive second limit value (+L2), the final operation amount calculation unit 405B sets the base operation amount DT1 to the final operation amount DT2. The second limit value L2 itself is a positive value (L21>0). B) In the case of the non-supercharged propulsion state 1) At the time of DT1 < -L2 DT2=−L2 2) At the time of DT1 > +L2 DT2=+L2 3) At the time of -L2 <= DT1 <= +L2 DT2=DT1

[0050] In the present embodiment, the pressure of the exhaust gas on the upstream side of the turbine 202 acts as an opening-side capacity of the wastegate valve 31. The first limit value L1 is set in advance to a value corresponding to a minimum operating amount that can maintain a state in which the wastegate valve 31 is pressed to the fully closed position against the pressure of the exhaust gas acting on the wastegate valve 31 in a driving condition where the pressure of the exhaust gas on the upstream side of the turbine 202 becomes maximum in the supercharging driving state. For example, the first limit value L1 is set to an operating amount increased by a safety factor of tens of percent (for example, 20%) from an operating amount that balances the maximum pressure capacity of the exhaust gas in the fully closed state and the supercharging driving state.According to this configuration, in the entire region of the supercharge driving state, the wastegate valve 31 can be securely kept in the fully closed state and the power consumption of the electric valve actuator 34 can be reduced.

[0051] The second limit value L2 is set in advance to a value corresponding to a minimum operating amount that can maintain a state in which the wastegate valve 31 is pushed to the fully closed position against the pressure of the exhaust gas acting on the wastegate valve 31 in a driving condition where the pressure of the exhaust gas on the upstream side of the turbine 202 becomes maximum in the non-supercharging driving state. For example, the second limit value L2 is set to an operating amount increased by a safety factor of tens of percent (for example, 20%) from an operating amount that balances the maximum pressure capacity of the exhaust gas in the fully closed state and the non-supercharging driving state.According to this configuration, in the entire region of the non-supercharged state, while the wastegate valve 31 can be safely controlled to the fully closed state, the power consumption of the electric valve actuator 34 can be reduced.

[0052] The difference between the first limit value L1 and the second limit value L2 becomes a value corresponding to the difference between the maximum exhaust gas pressure in the supercharged driving state and the maximum exhaust gas pressure in the non-supercharged driving state. Depending on the supercharged driving state, the limit value can be adjusted to an appropriate value. <Verhalten von Betriebsbetrags-Beschränkungsverarbeitung>

[0053] Next, the behavior of the operation amount restriction processing will be explained with reference to the timing chart of Fig. 8. The horizontal axis of Fig. 8 is elapsed time. The vertical axis of the upper graph is the opening degree of the wastegate valve 31, and the upper graph shows the behavior of the actual opening degree, the target opening degree, the true fully closed position, and the learned fully closed position. The vertical axis of the lower graph is the operating amount of the solenoid valve actuator 34, and the lower graph shows the behavior of the base operating amount DT1 and the final operating amount DT2.

[0054] Although the learned fully closed position naturally corresponds to the opening degree 0 [%], the true fully closed position varies due to thermal expansion of the turbocharger element and the like from the state where the fully closed position was last learned, and the opening degree becomes 2 [%] corresponding to the true fully closed position. This means that it enters the state where the fully closed position erroneous learning occurs. Before time T1, the target opening degree is set to 6 [%]. Since the target opening degree 6 [%] is larger than the opening degree 2 [%] corresponding to the true fully closed position, the true opening degree calculated based on Equation (1) follows the target opening degree 6 [%] through feedback control. In this state, since the real opening degree follows the target opening degree, the basic operation amount DT1 and the final operation amount DT2 become a small value of less than or equal to ±20%.

[0055] At time T1, by changing the driving condition or the like, the target opening degree drops from 6 [%] to 1 [%]. The target opening degree 1 [%] is smaller than the opening degree 2 [%] corresponding to the true fully closed position. After reducing the target opening degree through feedback control, the base operating amount DT1 and the final operating amount DT2 increase in the negative direction, which is the closing side, and the true opening degree approaches the target opening degree. At time T2, the true opening degree reaches the opening degree 2 [%] corresponding to the true fully closed position, and the wastegate valve 31 abuts the fully closed position, and the true opening degree does not fall below 2 [%].

[0056] After time T2, since the difference between the actual opening degree and the target opening degree does not disappear, the basic operation amount DT1 continuously increases in the negative direction by the integration of feedback control and the like, reaching -100 [%], which is the maximum operation amount of the closing side at time T5. Unlike the present embodiment, if the operation amount limitation processing is not performed but excessive energization is performed, fuel efficiency is affected by an increase in the power consumption of the electric valve actuator 34, and there is a fear that the electric motor may overheat and fail.

[0057] In the present embodiment, in the case of determining that a supercharged driving state exists when the magnitude of the basic operation amount DT1 reaches the first limit value L1 set to 60 [%] at time T4, the magnitude of the basic operation amount DT1 is upper-limited by the first limit value L1 after time T4. That is, after time T4, since the basic operation amount DT1 becomes smaller than the negative first limit value -60 [%], the final operation amount DT2 is set to the negative first limit value (-60 [%]). In the supercharged driving state, while the wastegate valve 31 is pushed to the fully closed position, the power consumption of the electric valve actuator 34 can be reduced, and the possibility of overheating of the electric motor can be reduced.

[0058] In the case of determining that the non-supercharging driving state exists, when the magnitude of the basic operation amount DT1 reaches the second limit value L2, which is set to 40 [%] smaller than the first limit value L1 at time T3, the magnitude of the basic operation amount DT1 is upper-limited by the second limit value L2, which is preset to a smaller value than the first limit value L1 after time T3. This means that after time T3, since the basic operation amount DT1 becomes smaller than the negative second limit value (-40 [%]), the final operation amount DT2 is set to the negative second limit value (-40 [%]).In the non-supercharging driving state in which the pressure of the exhaust gas is lower than the supercharging driving state, while the wastegate valve 31 is pushed to the fully closed position by the second limit value L2 which is set to a smaller value than the first limit value L1, the power consumption of the electric valve actuator 34 can be further reduced more than the supercharging driving state, and the possibility of overheating of the electric motor can be further reduced. <flussdiagramm>

[0059] The above processing of each of the control units 400 to 406 and the like of the controller 40 can be carried out as shown in Fig. 9 shown flowchart. The processing of the flowchart in Fig. 9 is implemented recurrently, for example, in each constant operation cycle, while the arithmetic processing unit 90 implements the software (a program) stored in the storage device 91.

[0060] In step S101, as mentioned above, the driving condition detection unit 400 implements the driving condition detection processing (a driving condition detection step) that detects the driving condition of the internal combustion engine 10 and the vehicle based on the output signals of various types of sensors and the like. In the present embodiment, the driving condition detection unit 400 detects the operating position of the wastegate valve 31 and the actual supercharging pressure. In step S102, as mentioned above, the target supercharging pressure calculation unit 401 implements the target supercharging pressure calculation processing (a target supercharging pressure calculation step) that calculates the target supercharging pressure, which is the target pressure of the supercharging pressure.

[0061] In step S103 to step S105, as mentioned above, the supercharged state determination unit 402 implements the supercharged state determination processing (a supercharged state determination step) that determines whether a supercharged driving state or a non-supercharged driving state exists. In the present embodiment, in step S103, the supercharged state determination unit 402 determines whether or not a supercharged driving state exists. If it determines that a supercharged driving state exists, the supercharged state determination unit 402 proceeds to step S104 and sets a supercharged state determination flag FA to 1, representing a supercharged driving state (FA=1).In case of determining that there is no supercharging driving state, the supercharging state determining unit 402 proceeds to step S105 and sets the supercharging state determining flag FA to 0, which represents the non-supercharging driving state (FA=0).

[0062] In step S106 to step S108, as mentioned above, the target opening degree calculation unit 403 implements the target opening degree calculation processing (a target opening degree calculation step) that calculates the target opening degree of the wastegate valve 31. In the present embodiment, in step S106, the target opening degree calculation unit 403 determines whether the supercharged state determination flag FA is set to 1 or not, which represents the supercharged driving state. Then, in the case where the supercharging state determination flag FA is set to 1 and it is determined that the supercharging driving state exists, the target opening degree calculation unit 403 proceeds to step S107 and calculates the opening degree of the wastegate valve 31 to bring the real supercharging pressure close to the target supercharging pressure as the target opening degree.On the other hand, in the case where the supercharging state determination flag FA is set to 0 and it is determined that the non-supercharging driving state exists, the target opening degree calculation unit 403 proceeds to step S108 and calculates the opening degree of the wastegate valve 31, which is set in advance for each driving condition of the internal combustion engine 10, as the target opening degree.

[0063] In step S109, as mentioned above, the true opening degree calculation unit 404 implements the true opening degree calculation processing (a true opening degree calculation step) that calculates the true opening degree of the wastegate valve 31 based on the operating position of the wastegate valve 31 detected by the driving condition detection unit 400. In the present embodiment, the true opening degree calculation unit 404 learns the operating position of the wastegate valve 31 at the time of determining that the wastegate valve 31 is in the fully closed state as the fully closed position; and calculates the true opening degree based on the operating position of the wastegate valve 31 based on the learned fully closed position.

[0064] In step S110 to step S114, as mentioned above, the operation amount calculation unit 405 implements the operation amount calculation processing (an operation amount calculation step) that calculates the operation amount of the solenoid valve actuator 34. In step S110, the basic operation amount calculation unit 405A implements the basic operation amount calculation processing that calculates the basic operation amount DT1 to bring the actual opening degree close to the target opening degree. In the present embodiment, the basic operation amount calculation unit 405A calculates the basic operation amount DT1 through feedback control based on the difference between the target opening degree and the actual opening degree.

[0065] In step S111 to step S114, the final operation amount calculation unit 405B implements the operation amount restriction processing that, in the case of determining that the supercharging driving state exists, calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 by the first limit value L1 set in advance as the final operation amount DT2, and, in the case of determining that a non-supercharging driving state exists, calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 by the second limit value L2 set in advance to a value smaller than the first limit value L1 as the final operation amount DT2.

[0066] In the present embodiment, in step S111, the final operation amount calculation unit 405B determines whether or not the supercharging state determination flag FA is set to 1, representing the supercharging driving state. In the case where the supercharging state determination flag FA is set to 1, representing the supercharging driving state, the final operation amount calculation unit 405B proceeds to step S112 and sets a threshold value LM to the first threshold value L1; and in the case where the supercharging state determination flag FA is set to 0, representing the non-supercharging driving state, the final operation amount calculation unit 405B proceeds to step S113 and sets the threshold value LM to the second threshold value L2.Then, in step S114, the final operation amount calculation unit 405B performs minimum value picking (min) which picks out a smaller value between the basic operation amount DT1 and the positive limit value (+LM), performs maximum value picking (max) which picks out a larger value between the picked minimum value and the negative limit value (-LM), and calculates the picked maximum value as the final operation amount DT2.

[0067] In the final step S115, as mentioned above, the actuator driving unit 406 implements the valve driving processing (a valve driving step) that performs control of the electric valve actuator 34 based on the final operation amount DT2 calculated in step S114. Embodiment 2

[0068] Next, the controller 40 according to Embodiment 2 will be explained. The discharge of the components similar to those in Embodiment 2 will be omitted. Although the basic configuration and processing of the internal combustion engine 10 and the controller 40 according to the present embodiment are the same as those of Embodiment 1, the operation amount limiting processing of the operation amount calculation unit 405 is partially different.

[0069] As in the case of Embodiment 1, the basic operation amount calculation unit 405A implements the basic operation amount calculation processing that calculates the basic operation amount DT1 in order to bring the real opening degree close to the target opening degree.As in the case of Embodiment 1, the final operation amount calculation unit 405B implements the operation amount limitation processing that, in the case of determining that the supercharging driving state exists, calculates an operation amount determined by performing an upper limit on the magnitude of the basic operation amount DT1 by a preset first limit value L1 as the final operation amount DT2, and in the case of determining that a non-supercharging driving state exists, calculates an operation amount determined by performing an upper limit on the magnitude of the basic operation amount DT1 by the second limit value L2, which is preset to a value smaller than the first limit value L1, as the final operation amount DT2.

[0070] Unlike Embodiment 1, in the case of determining that the supercharge driving state exists, when a state in which the magnitude of the basic operation amount DT1 is upper-limited by the first limit value L1 continues for more than a preset switching determination time, the final operation amount calculation unit 405B switches the limit value used for performing the upper limit on the magnitude of the basic operation amount DT1 from the first limit value L1 to the second limit value L2, and calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 by the second limit value L2 as the final operation amount DT2.

[0071] Depending on specifications such as heat transfer from the exhaust pipe to the solenoid valve actuator 34 and the cooling performance of the solenoid valve actuator 34, even if the magnitude of the operating amount is reduced to the first limit value L1, the electric motor may overheat due to driving at the first limit value L1 for a long time. According to the above-mentioned configuration, when the state of being upper-limited by the first limit value L1 continues for longer than the switching determination time, since the limit value is switched from the first limit value L1 to the second limit value L2 and the operating amount is reduced to the second limit value L2, the overheating of the electric motor can be more safely reduced.When the magnitude of the operation amount is reduced from the first limit value L1 in the supercharge driving state to the second limit value L2, although the wastegate valve 31 can open under the condition that the pressure of the exhaust gas is large, overheating of the electric motor is preferentially suppressed.

[0072] In the case of determining that the supercharged state prevails, when the magnitude of the basic operation amount DT1 is no longer upper-limited by the second limit value L2 used for performing the upper limit of the magnitude of the basic operation amount DT1 after switching the limit value from the first limit value L1 to the second limit value L2, the final operation amount calculation unit 405B switches again the limit value used for performing the upper limit of the magnitude of the basic operation amount DT1 from the second limit value L2 to the first limit value L1 and ends a limit-forced switching processing.

[0073] According to this configuration, when no longer upper-limited by the second limit value L2, after switching the limit value to the second limit value L2, since it can be determined that the state where the operation amount became excessive ceased to continue, the limit value can be returned to the first limit value L1 which is a larger value, and the control performance of the opening degree control can be improved. <flussdiagramm>

[0074] The processing of each of the control units 400 to 406 and the like of the controller 40 according to Embodiment 2 can be carried out as shown in Fig. 10 shown flowchart. The processing of the flowchart in Fig. 10 is implemented recurrently, for example, in each constant operation cycle, while the arithmetic processing unit 90 implements software (a program) stored in the storage unit 91.

[0075] Since the processing from step S201 to step S210 is the same as the processing from step S101 to step S110 in Fig. 9 of Embodiment 1, explanation is omitted.

[0076] In steps S211 to S224, the final operation amount calculation unit 405B implements the operation amount limiting processing and the limit value forcible switching processing according to the above-mentioned present embodiment. In step S211, the final operation amount calculation unit 405B determines whether or not the supercharged state determination flag FA is set to 1, which represents the supercharged driving state.

[0077] In the case where the supercharged state determination flag FA is set to 1, representing the supercharged driving state, the final operation amount calculation unit 405B proceeds to step S212 and determines whether a threshold compulsory switching flag FB described below is set to 0. In the case where the threshold compulsory switching flag FB is set to 0, representing non-execution of the threshold compulsory switching processing, the final operation amount calculation unit 405B proceeds to step S213 and sets the threshold value LM to the first threshold value L1; and in the case where the threshold compulsory switching flag FB is set to 1, representing execution of the threshold compulsory switching, the final operation amount calculation unit 405B proceeds to step S214 and sets the threshold value LM to the second threshold value L2.

[0078] Then, in step S215, the final operation amount calculation unit 405B determines whether the magnitude (absolute value) of the basic operation amount DT1 is larger than the limit value LM or not. If determining that the magnitude is larger than the limit value LM, the final operation amount calculation unit 405B proceeds to step S216, determines that the magnitude of the basic operation amount DT1 is upper-limited by the limit value LM, and increments a switching determination counter CT by 1 to measure a time duration of a state in which the magnitude of the basic operation amount DT1 is upper-limited by the limit value LM. The value obtained by thus multiplying the calculation cycle by the switching determination counter CT corresponds to the time.On the other hand, in the case of determining that the size is not larger than the limit value LM, the final operation amount calculation unit 405B proceeds to step S217, determines that the size of the basic operation amount DT1 is not upper-limited by the first limit value L1 or upper-limited by the second limit value L2 to which switching is forcibly carried out, and resets the switching determination counter CT to 0.

[0079] Then, in step S218, the final operation amount calculation unit 405B determines whether the switching determination counter CT is less than or equal to a preset switching determination value C1. If the switching determination counter CT is determined to be less than or equal to the switching determination value C1, the final operation amount calculation unit 405B proceeds to step S219, determines that the state in which the magnitude of the basic operation amount DT1 is limited by the first limit value L1 above does not continue for longer than the switching determination time, or that the magnitude of the basic operation amount DT1 is not limited by the second limit value L2 above, and sets the limit value compulsory switching flag FB to 0, which represents the non-execution of the limit value compulsory switching processing.On the other hand, in the case of determining that the switching determination counter CT is not less than or equal to the switching determination value C1, the final operation amount calculation unit 405B proceeds to step S220, determines that the state where the magnitude of the basic operation amount DT1 is limited by the first limit value L1 above continues longer than or equal to the switching determination time, and sets the limit value compulsory switching flag FB to 1, which represents the execution of the limit value compulsory switching processing.

[0080] On the other hand, in the case where the supercharged state determination flag FA is not set to 1, representing the supercharged driving state, in step S211, and it is determined that the non-supercharged driving state exists, the final operation amount calculation unit 405B proceeds to step S21 and sets the second threshold value L2 to the weight LM. Then, since the threshold forced switching processing is not implemented in the non-supercharged state, the final operation amount calculation unit 405B sets the switching determination counter CT to 0 in step S222 and sets the threshold forced switching flag FB to 0 in step S223.

[0081] Then, in step S224, the final operation amount calculation unit 405B performs minimum value picking (min) that picks out a smaller value between the basic operation amount DT1 and the positive limit value (+LM), performs maximum value picking (max) that picks out a larger value between the picked minimum value and the negative limit value (-LM), and calculates the picked maximum value as the final operation amount DT2.

[0082] In the final step S225, the actuator driving unit 406 implements the drive processing (the valve driving step) that executes the drive control of the electric valve actuator 34 based on the final operation amount DT2 calculated in step S224. Embodiment 3

[0083] Next, the controller 40 according to Embodiment 3 will be explained. The discharge of the constituent elements, which are the same as those in Embodiment 1, will be omitted. Although the basic configuration and processing of the internal combustion engine 10 and the controller 40 according to the present embodiment are the same as those of Embodiment 1, the operation amount limit calculation of the operation amount calculation unit 405 is partially different.

[0084] As in the case of Embodiment 1, the basic operation amount calculation unit 405A implements the basic operation amount calculation processing that calculates the basic operation amount DT1 to bring the real opening degree close to the target opening degree.As in Embodiment 1, the final operation amount calculation unit 405B implements the operation amount limitation processing that, in the case of determining that the supercharging driving state exists, calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 by the preset first limit value L1 as the final operation amount DT2, and, in the case of determining that the non-supercharging driving state exists, calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 by the second limit value L2, which is set in advance to a value smaller than the first value L1, as the final operation amount DT2.

[0085] Unlike Embodiment 1, when the operating position of the wastegate valve 31 is within a preset variation range of the fully closed position, and the basic operation amount DT1 that operates the wastegate valve 31 in the closing direction is calculated, the final operation amount calculation unit 405B implements the operation amount limitation calculation that calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 of the closing direction by the first limit value L1 or the second limit value L2 as the final operation amount DT2; and otherwise, the final operation amount calculation unit 405B does not implement the operation amount limitation processing and calculates the basic operation amount DT1 to the final operation amount DT2.

[0086] According to this configuration, when the wastegate valve 31 is approaching the fully closed position and the solenoid valve actuator 34 is controlled in the closing direction, the operating amount can be limited and prevented from becoming excessively large due to erroneous setting or erroneous learning of the fully closed position. On the other hand, since the operating amount is otherwise not limited, the operating amount can be set to a large value, and the actual opening degree can be brought close to the target opening degree with good responsiveness.Even in the case where the operating position of the wastegate valve 31 is within the variation range of the fully closed position, since the operation amount is not limited when the electric valve actuator 34 is controlled in the opening direction, at the time of opening the wastegate valve 31 from the fully closed position, the wastegate valve 31 can be opened with good responsiveness.

[0087] In the present embodiment, when the output voltage Vs of the valve position sensor 43 is within the variation range of the fully closed position and the basic operation amount DT1 is less than 0, the final operation amount calculation unit 405B calculates an operation amount determined by performing the upper limit on the magnitude of the basic operation amount DT1 of the flowing direction by the first limit value L1 or the second limit value L2 as the final operation amount DT2; and otherwise, the final operation amount calculation unit 405B calculates the basic operation amount DT1 as the final operation amount DT2. As shown in Fig. 6, the variation range of the fully closed position is set in advance according to the fluctuation range of the output voltage Vs of the valve position sensor 43 corresponding to the fully closed position by factors such as the deviation of the mounting position of the wastegate valve 31, the drift of the output voltage by the temperature characteristic of the valve position sensor 43, and the thermal expansion of the turbocharger element. <flussdiagramm>

[0088] The processing of each of the control units 400 to 406 and the like of the controller 40 according to Embodiment 3 can be performed as shown in Fig. 11 shown flowchart. The processing of the flowchart in Fig. 11 is implemented recurrently, for example, in each constant operation cycle, while the arithmetic processing unit 90 implements software (a program) stored in the storage device 91.

[0089] Since the processing from step S301 to step S310 is the same as the processing from step S101 to step S110 in Fig. 9 of Embodiment 1, the explanation is omitted.

[0090] From step S311 to step S316, the final operation amount calculation unit 405B implements the operation amount limit calculation and the limit value forced switching processing according to the above-mentioned present embodiment. In step S311, the final operation amount calculation unit 405B determines whether the operation position of the wastegate valve is within a preset variation range of the fully closed position, and calculates the basic operation amount that operates the wastegate valve in a closing direction.

[0091] In case of determining that the working position is within the variation range of the fully closed position and the basic operation amount DT1 of the closing direction is calculated in step S311, the final operation amount calculation unit 405B proceeds to step S312 and determines whether or not the supercharged state determination flag FA is set to 1, which represents the supercharged driving state. In the case where the supercharged state determination flag FA is set to 1, representing the supercharged driving state, the final operation amount calculation unit 405B proceeds to step S313 and sets a limit value LM to the first limit value L1, and in the case where the supercharged state determination flag FA is set to 0, representing the non-supercharged state, the final operation amount calculation unit 405B proceeds to step S314 and sets the limit value LM to the second limit value L2.

[0092] Then, in step S315, the final operation amount calculation unit 405B performs maximum value picking (max) which picks out a larger value between the basic operation amount DT1 and the negative limit value (-LM), and calculates the picked maximum value as the final operation amount DT2.

[0093] On the other hand, in case of determining that the operation position is not within the variation range of the fully closed position, or the basic operation amount DT1 of the closing direction is not calculated in step S311, the final operation amount calculation unit 405B proceeds to step S316 and calculates the basic operation amount DT1 as the final operation amount DT2 without implementing the operation amount limiting processing.

[0094] In the final step S317 as described above, the actuator driving unit 406 implements the valve driving processing (the valve driving step) that performs the drive control of the electric valve actuator 34 based on the final operation amount DT2 calculated in step S315 or step S316. <Andere Ausführungsformen>

[0095] Finally, other embodiments of the present invention will be explained. Each of the configurations of embodiments to be explained below is not limited to being set separately, but can be used in combination with the configurations of other embodiments as long as no discrepancy occurs. (1) In the above-mentioned Embodiments 1 and 2, the case where the operation amount calculation unit 405 calculates an operation amount obtained by performing an upper limit on the magnitude of the basic operation amount DT1 in both the closing direction and the opening direction by the first limit value L1 or the second limit value L2 as the final operation amount DT2 has been explained. However, embodiments of the present invention are not limited to the above case. That is, the operation amount calculation unit 405 may perform an upper limit on the magnitude of the basic operation amount DT1 in only the closing direction by the first limit value L1 or the second limit value L2, or may perform an upper limit on the magnitude of the basic operation amount DT1 in only the opening direction by the first limit value L1 or the second limit value L2. (2) In each of the above embodiments, the case where the operation amount in the closing direction becomes a negative value and the operation amount in the opening direction becomes a positive value has been explained. However, embodiments of the present invention are not limited to the above case. That is, the operation amount in the closing direction may be given a positive value and the operation amount in the opening direction may be given a negative value. (3) In the above-mentioned Embodiment 3, when the operating position of the wastegate valve 31 is within a preset variation range of the fully open position, and the basic operation amount DT1 that operates the wastegate valve 31 in the opening direction is calculated, the final operation amount calculation unit 405B may implement the operation amount limiting processing that calculates an operation amount obtained by performing an upper limit on the size of the basic operation amount DT1 of the opening direction by the first limit value L1 or the second limit value L2 as the final operation amount DT2; and otherwise, the final operation amount calculation unit 405B may not implement the operation amount limiting processing and calculates the basic operation amount DT1 of the final operation amount DT2.< / flussdiagramm> < / flussdiagramm> < / flussdiagramm>

Claims

[1] A controller (40) for an internal combustion engine (10) provided with a turbocharger (20) having a turbine (202) provided in an exhaust path (15), a compressor (201) provided in an intake path (11) and rotating integrally with the turbine (202), an exhaust bypass path (30) allowing the upstream and downstream sides of the turbine (202) to communicate, a wastegate valve (31) adjusting the flow rate of exhaust gas flowing through the exhaust bypass path (30), and an electrovalve actuator (34) changing an actuating position of the wastegate valve (31), the controller (40) for the internal combustion engine (10) comprising: a driving condition detection unit (400) that detects the actuating position of the wastegate valve (31) and a true supercharging pressure, which is an actual value of a pressure of intake air compressed by the compressor (201); a supercharging state determination unit (402) that determines whether a supercharging driving state exists in which the actual supercharging pressure is higher than atmospheric pressure or is expected to become higher than atmospheric pressure, or a non-supercharging driving state exists in which the actual supercharging pressure is less than or equal to atmospheric pressure or is expected to become less than or equal to atmospheric pressure; a target opening degree calculation unit (403) that calculates a target opening degree of the wastegate valve (31); a true opening degree calculation unit (404) that calculates a true opening degree of the wastegate valve (31) based on the operating position of the wastegate valve (31); an operation amount calculation unit (405) that calculates a basic operation amount (DT1) to bring the actual opening degree close to the target opening degree; in the case of determining that a supercharging driving state exists, calculates an operation amount determined by upper-limiting a magnitude of the basic operation amount (DT1) by a preset first limit value (L1) as a final operation amount (DT2); and in the case of determining that a non-supercharging driving state exists, calculates an operation amount determined by upper-limiting the magnitude of the basic operation amount by a second limit value, which is preset to a smaller value than the first limit value, as the final operation amount; and an actuator drive unit (406) that performs drive control of the electric valve actuator (34) based on the final operation amount. [2] The controller (40) for the internal combustion engine (10) according to claim 1, wherein the first limit value (L1) is set in advance to a value corresponding to a minimum operation amount that can maintain a state in which the wastegate valve (31) has been pushed to a fully closed position against a pressure of the exhaust gas acting on the wastegate valve (31) in a driving position where a pressure of the exhaust gas at the upstream side of the turbine (202) becomes maximum in the supercharging operation state, and wherein the second limit value (L2) is set in advance to a value corresponding to a minimum operation amount that can maintain a state in which the wastegate valve (31) has been pushed to the fully closed position against the pressure of the exhaust gas acting on the wastegate valve (31) in a driving condition,where the pressure of the exhaust gas on the upstream side of the turbine (202) becomes maximum in the non-supercharged drive state., [3] A controller (40) for the internal combustion engine (10) according to claim 1 or 2, further comprising a target supercharging pressure calculation unit (401) that calculates a target supercharging pressure which is a target value of the pressure of the intake air compressed by the compressor (201), wherein, in the case of determining that the supercharging driving state exists, the target opening degree calculation unit (403) calculates an opening degree of the wastegate valve (31) to bring the real supercharging pressure close to the target supercharging pressure as the target opening degree; and in case of determining that the non-supercharging driving state prevails, the target opening degree calculation unit (403) calculates an opening degree of the wastegate valve (31), which is set in advance for each driving condition of the internal combustion engine (10), as the target opening degree. [4] The controller (40) for the internal combustion engine (10) according to any one of claims 1 to 3, wherein, in the case of determining that the supercharged driving state exists, when a state in which the magnitude of the basic operation amount (DT1) is upper limited by the first limit value (L1) continues for more than a predetermined set switching determination time, the operation amount calculation unit (405) switches a limit value used for performing the upper limit on the magnitude of the basic operation amount (DT1) from the first limit value (L1) to the second limit value (L2), and calculates an operation amount obtained by performing the upper limit on the magnitude of the basic operation amount (DT1) by the second limit value (L2) as the final operation amount (DT2). [5] The controller (40) for the internal combustion engine (10) according to claim 4, wherein, in the case of determining that the supercharged driving state exists when the magnitude of the basic operation amount (DT1) is no longer upper limited by the second limit value (L2) after switching the limit value used for performing the upper limit on the magnitude of the basic operation amount (DT1) from the first limit value (L1) to the second limit value (L2), the operation amount calculation unit (405) switches the limit value used for performing the upper limit on the magnitude of the basic operation amount (DT1) from the second limit value (L2) to the first limit value (L1) again. [6] The controller (40) for the internal combustion engine (10) according to any one of claims 1 to 5, wherein, when the operating position of the wastegate valve (31) is within a preset variation range of the fully closed position and the basic operation amount (DT1) that operates the wastegate valve (31) in a closing direction is calculated, the operation amount calculation unit (405) calculates an operation amount determined by performing the upper limit on the magnitude of the basic operation amount (DT1) of the closing direction by the first limit value (L1) or the second limit value (L2) as the final operation amount (DT2); otherwise, the operation amount calculation unit (405) calculates the basic operation amount (DT1) as the final operation amount (DT2). [7] A control method for an internal combustion engine (10) equipped with a turbocharger (20) having a turbine (202) provided in an exhaust path (15), a compressor (201) provided in an intake path (11) and rotating integrally with the turbine (202), an exhaust bypass path (30) allowing the upstream and downstream sides of the turbine (202) to communicate with each other, a wastegate valve (31) adjusting the flow rate of exhaust gas flowing through the exhaust bypass path (30), and an electrovalve actuator (34) changing the operating position of the wastegate valve (31), the control method for the internal combustion engine (10) comprising: a driving condition detection step that detects the operating position of the wastegate valve (31) and a true supercharging pressure, which is an actual value of a pressure of intake air compressed by the compressor (201); a supercharging state determining step that determines whether a supercharging driving state exists in which the actual supercharging pressure is higher than atmospheric pressure or is expected to become higher than atmospheric pressure, or a non-supercharging driving state exists in which the actual supercharging pressure is less than or equal to atmospheric pressure or is expected to become less than or equal to atmospheric pressure; a target opening degree calculation step that calculates a target opening degree of the wastegate valve (31); a true opening degree calculation step that calculates a true opening degree of the wastegate valve (31) based on the operating position of the wastegate valve (31); an operation amount calculation step that calculates a basic operation amount (DT1) to bring the actual opening degree close to the target opening degree; in the case of determining that a supercharge driving state exists, an operation amount determined by performing an upper limit on a magnitude of the basic operation amount (DT1) by a preset first limit value (L1) is calculated as a final operation amount (DT2); and in the case of determining that a non-supercharge driving state exists, an operation amount determined by performing an upper limit on the magnitude of the base operating amount (DT1) is determined by a second limit value (L2) which is set in advance to a smaller value than the first limit value (L1), is calculated as a final operating amount (DT2); and an actuator driving step that performs drive control of the solenoid valve actuator (34) based on the final operation amount (DT2).

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