JP6518612B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device of an internal combustion engine.

An internal combustion engine equipped with a turbocharger, which is an example of a turbocharger, is conventionally known (for example, Patent Document 1). The supercharging pressure control of the turbocharger is performed, for example, by adjusting the degree of opening of an exhaust bypass valve (waste gate valve) disposed in an exhaust bypass passage that bypasses the turbine of the turbocharger.
In the conventional example, when a failure occurs in the opening / closing mechanism of the exhaust bypass valve, control is performed to ensure the drivability of the vehicle at the time of the failure.

JP 2003-328766 A

  However, in the prior art, although the failure on the opening / closing mechanism side of the exhaust bypass valve is considered, the failure of the sensor for detecting the opening degree of the exhaust bypass valve is not particularly considered. Therefore, the decrease in drivability in the case where the sensor for detecting the operating state of the adjustment means of the supercharging pressure in the exhaust gas bypass valve etc. becomes defective becomes a problem.

  Therefore, in view of the above problems, the present invention has an object to provide a control device of an internal combustion engine that suppresses a decrease in drivability when a sensor for detecting the operating state of the supercharging pressure adjusting means fails. .

In order to solve the above problems, according to the present invention, when the adjusting means for adjusting the supercharging pressure of the supercharger and the sensor for detecting the operating state of the adjusting means fail, the supercharging pressure changes to the operating state of the internal combustion engine. Control means for controlling the adjusting means to converge to a second target boost pressure which is lower than the first target boost pressure by a predetermined value than the first target boost pressure , the control means responding to an increase in the number of revolutions of the internal combustion engine , Gradually increase the predetermined value.

  According to the control device of the present invention, even when the sensor for detecting the operating state of the supercharging pressure adjusting means fails, the lowering of the supercharging pressure is suppressed, so the lowering of the drivability is suppressed. Can.

It is an explanatory view showing an example of composition of an internal-combustion engine in this embodiment. It is an explanatory view showing an example of hardware constitutions of ECU (Engine Control Unit) in this embodiment. It is an explanatory view showing the relation between target torque, rotation speed, and target supercharging pressure. It is explanatory drawing of the characteristic which shows an example of the output voltage of the opening degree sensor for WGV (Waste Gate Valve). It is an explanatory view showing an example of a timing chart of control processing in this embodiment. It is a flowchart which shows an example of the drive processing of WGV in this embodiment. It is a flowchart which shows an example of the supercharging pressure control processing in this embodiment. It is a flowchart which shows a 1st modification. It is explanatory drawing which shows an example of the timing chart of a 1st modification. It is explanatory drawing which shows an example of the timing chart of a 2nd modification. It is a flowchart which shows an example of a 2nd modification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.
[Overview of the embodiment]
The technology described in the present embodiment relates to, for example, a control device for an internal combustion engine that can perform control to suppress a decrease in drivability when a sensor that detects the opening degree of an electronically controlled waste gate valve (WGV) breaks down. .

  Conventionally, when a sensor for detecting the opening degree of the electronically controlled WGV fails, it is necessary to suppress unexpected acceleration (UA: Unexpected Acceleration) and to suppress excessive supercharging. Therefore, in the case of a sensor failure, as an example of fail-safe control to control on the safe side, WGV is forcibly opened in the direction to suppress the increase in boost pressure to bypass the exhaust gas, and the turbocharger turbine and compressor are To reduce the rotation of the That is, in failsafe control at the time of failure of the sensor, for example, the internal combustion engine is driven in a state where supercharging is suppressed to perform retraction operation (so-called limp home operation).

  Further, as a means for suppressing the occurrence of excessive supercharging at the time of failure of the sensor, for example, when the target supercharging pressure is higher than the equivalent of the atmospheric pressure (about 100 [KPa]), an electronically controlled throttle valve is used. It is closing the valve and implementing fuel cut.

  By the way, in recent years, in order to compensate for the reduction in engine displacement due to the downsizing of the internal combustion engine, a downsizing engine that achieves engine output by supercharging intake air with a turbocharger such as a turbocharger is attracting attention. There is. In the case of an automobile equipped with such a downsizing engine, if the WGV is forcibly opened at the time of a failure of the above sensor to suppress the supercharging pressure, the amount of intake air will be low in the low speed rotation range around 1500 to 2000 [rpm], for example. It does not increase, and as a result, there is a concern that the lack of engine torque will occur and the drivability will decrease. That is, in the case of the downsizing engine, there is a concern that the shortage of the engine torque in the low speed range makes the evacuation operation difficult.

  Therefore, in the present embodiment, as will be described in detail in the following description, in the case of a failure of the sensor in an automobile equipped with a downsizing engine, for example, the supercharging pressure in the low speed rotation region while avoiding unexpected acceleration. To provide a control device capable of obtaining the required engine torque. The control means provided by this control device is an example of failsafe control. Thereby, when the said sensor fails, the fall of drivability can be suppressed.

[Configuration Example of Internal Combustion Engine]
FIG. 1 is an explanatory view showing a configuration example of an internal combustion engine in the present embodiment. An engine control unit (hereinafter referred to as "ECU") 1 shown in FIG. 1 realizes control of an internal combustion engine. The ECU 1 is an example of a control device, and is, for example, a device that electronically controls various devices mounted on a vehicle.

  In FIG. 1, an engine 30 is an example of an internal combustion engine, and is a gasoline engine for a motor vehicle that performs spark ignition combustion. This gasoline engine is, for example, a downsizing engine.

  Further, in the intake system, an intake air amount sensor for detecting the flow rate of air having passed through the air cleaner 22 (hereinafter referred to as "intake air amount") in the intake pipe 21 for introducing air (intake air) in the atmosphere. 23 are attached. The air cleaner 22 removes dust and the like contained in the air. The intake air amount sensor 23 can use, for example, a hot-wire type flow meter such as an air flow meter.

  In the intake pipe 21 located downstream of the intake air amount sensor 23, for example, the compressor 24 a of the turbocharger 24, the intercooler 25, and an air bypass valve (hereinafter referred to as “ABV” (Air Bypass Valve)) 26. An ABV opening sensor 26a, a supercharging pressure sensor 27, a throttle valve 28, and a throttle opening sensor (TPS: Throttle Position Sensor) 28a are provided.

  The turbocharger 24 is a device that feeds compressed air into the engine 30 and boosts the thermal efficiency of the engine 30 in order to supercharge air. The turbocharger 24 has a compressor 24a, a turbine 24b, and a shaft 24c coaxially connecting them. The compressor 24a compresses air using rotational energy obtained via the shaft 24c as the turbine 24b is rotated by exhaust gas.

  The intercooler 25 cools the air that has passed through the turbocharger 24. The intercooler 25 may be either an air-cooling type or a water-cooling type.

ABV26 is, Ru valve der of the electronically controlled. A bypass pipe 26b for bypassing between the upstream side of the compressor 24a and the downstream side of the compressor 24a of the turbocharger 24 is disposed to connect between the ABV 26 and the intake pipe 21 to which the intake air amount sensor 23 is attached. It is done.

  The ABV opening sensor 26a detects the opening of the ABV 26. Here, the configuration of the ABV opening degree sensor 26a is not particularly limited as long as the opening degree of the ABV 26 can be detected.

  The supercharging pressure sensor 27 is an output value indicating the pressure (absolute pressure) in the intake pipe 21 located upstream of the throttle valve 28 and located between the compressor 24 a of the turbocharger 24 and the throttle valve 28. The feed pressure P [Pa] (throttle upstream pressure) is detected.

The throttle valve 28 is disposed in the intake pipe 21 and opens and closes in conjunction with an accelerator pedal (not shown) to control the intake air amount Q. In this embodiment, as an example, an electronic control type that opens and closes in accordance with the opening degree of the accelerator pedal (accelerator opening degree (angle) [θ]) is adopted. Here, the opening degree of the accelerator pedal is detected by an accelerator position sensor (APS) (not shown).
The throttle opening degree sensor 28a detects an opening degree (TVO [%]) indicating the open / close state of the throttle valve 28. The configuration of the throttle opening degree sensor 28a is not particularly limited as long as the opening degree of the throttle valve 28 can be detected.

  Further, a fuel injection valve 33 that injects fuel toward the intake port 32 is attached to the intake pipe 21 located downstream of the throttle valve 28. Further, at an intake port 32 for introducing air into the combustion chamber 34, an intake valve 31 for opening and closing its opening is disposed. The fuel injection valve 33 is, for example, an electromagnetic fuel injection valve.

  The fuel injected from the fuel injection valve 33 is introduced into the combustion chamber 34 along with the intake air through the gap between the intake port 32 and the intake valve 31, and is ignited and burned by the spark ignition of the spark plug 35. Then, the pressure due to the combustion pushes the piston 36 toward the crankshaft (not shown) to rotationally drive the crankshaft.

  Further, at an exhaust port 37 for leading the exhaust gas from the combustion chamber 34, an exhaust valve 38 for opening and closing the opening is disposed. By opening the exhaust valve 38, the exhaust gas is discharged to the exhaust pipe 39 through the gap between the exhaust port 37 and the exhaust valve 38. In the exhaust pipe 39, a turbine 24b of the turbocharger 24 and a catalytic converter 41 are arranged in this order along the exhaust flow direction.

  The WGV 40 is an electronically controlled valve and is disposed in a bypass pipe 40 b that bypasses the turbine 24 b of the turbocharger 24. The WGV 40 is an example of the adjusting means. The WGV opening sensor 40a detects the opening of the WGV 40. Here, the WGV opening degree sensor 40a is not particularly limited as long as the opening degree of the WGV 40 can be detected. The ECU 1 controls the opening degree (WGVO [%]) of the WGV 40. As a result, the exhaust gas flows through the bypass pipe 40b according to the WGV 40 opening degree, and, for example, the rotational force of the turbine 24b of the turbocharger 24 is reduced to suppress an increase in the supercharging pressure.

  The water temperature sensor 50 detects the temperature (water temperature) Tw [° C.] of the cooling water of the engine 30. The rotational speed sensor 51 detects an engine rotational speed (hereinafter referred to as “rotational speed”) Ne [rpm] in the engine 30. The atmospheric pressure sensor 52 detects atmospheric pressure (absolute pressure).

The catalytic converter 41 purifies harmful substances in the exhaust gas into harmless components, and simultaneously purifies, for example, CO (carbon monoxide), HC (hydrocarbon) and NO _x (nitrogen oxide) in the exhaust gas. It consists of a three-way catalyst.

[Example of hardware configuration of ECU 1]
FIG. 2 is an explanatory view showing an example of the hardware configuration of the ECU in the present embodiment. The ECU 1 shown in FIG. 2 includes a processor 10, a random access memory (RAM) 11, a flash memory 12, an input / output unit 13, and a bus 14. The processor 10, the RAM 11, the flash memory 12, and the input / output unit 13 are connected to one another via a bus 14.

  The processor 10 executes overall control of the ECU 1. Specifically, the processor 10 controls, for example, the RAM 11, the flash memory 12, and the input / output unit 13. However, the processor 10 may be a multi-core processor in which a plurality of CPUs (Central Processing Unit) cores are provided. The processor 10 incorporates a timer for measuring time. Details of the processing of the processor 10 will be described later with reference to a flowchart and the like.

The RAM 11 is, for example, a memory serving as a temporary work area for data used for arithmetic processing, and is a volatile memory in which stored contents disappear when power supply is shut off. The RAM 11 may be, for example, a dynamic RAM or a static RAM.
The flash memory 12 is, for example, a non-volatile semiconductor memory in which data is held even when the power supply is shut off.

  The input / output unit 13 receives the signal output from each sensor shown in FIG. 1 according to an instruction from the processor 10. The input / output unit 13 performs, for example, A / D conversion according to the received signal and stores the same in the RAM 11. The processor 10 generates control signals for driving vehicle-mounted devices such as the fuel injection valve 33, the spark plug 35, the throttle valve 28, the ABV 26 and the WGV 40 based on the signals from the respective sensors. Then, the processor 10 transmits these control signals to each in-vehicle device via the input / output unit 13 to control them.

  In addition, the processor 10 obtains, for example, the required target torque from the accelerator opening, reads the data of the map shown in FIG. 3, and obtains the target boost pressure based on the rotational speed and the target torque. Further, the processor 10 performs feedback control so that the boost pressure (actual boost pressure) detected by the boost pressure sensor 27 matches the target boost pressure.

  FIG. 3 is an explanatory view showing the relationship between the target torque, the rotational speed, and the target boost pressure. In FIG. 3, the x-axis represents the rotational speed, the y-axis represents the target torque, and the z-axis represents the target boost pressure. The map shown in FIG. 3 is based on, for example, simulation of numerical analysis, and illustrates the outline of the result for the convenience of description. In the map shown in FIG. 3, when the rotational speed and the target torque are determined, it means that the target boost pressure is determined, and one combination (rotational speed, target torque, target boost pressure) is illustrated. Data of the map shown in FIG. 3 is stored in advance in the flash memory 12. In addition, in this embodiment, the map shown in FIG. 3 can be calculated | required by experiment by a real machine. Moreover, how to obtain | require the target supercharging pressure by a map is an example, It is not limited to this, You may obtain | require the target supercharging pressure by another well-known means.

  The processor 10 opens the WGV 40 by the electric actuator (not shown) when, for example, the turbocharger 24 is driven and becomes higher than the target boost pressure in a normal state other than a failure in the WGV opening sensor 40a. Adjust to the side. As a result, the exhaust gas is bypassed by the bypass pipe 40b, and the rotational speed of the turbine 24b is reduced. When the rotational speed of the turbine 24b is reduced, the rotational speed of the compressor 24a is also reduced and the supercharging pressure is reduced.

  Conversely, the processor 10 adjusts the opening degree of the WGV 40 to the closing side by the electric actuator when the WGV opening sensor 40a is in a normal state, for example, when the actual charging pressure becomes lower than the target charging pressure to be targeted. . As a result, the bypass of the exhaust gas to the bypass pipe 40b is reduced, and the rotational speed of the turbine 24b is increased. As the rotational speed of the turbine 24b is increased, the rotational speed of the compressor 24a is also increased and the supercharging pressure is increased. The processor 10 repeats such boost pressure control to control the boost pressure to the target boost pressure.

  In the present embodiment, when adjusting the supercharging pressure using the opening degree signal of the WGV opening degree sensor 40a, the processor 10, for example, responds to the deviation between the target supercharging pressure and the actual supercharging pressure. Feedback control is performed on the amount of opening to be controlled by the WGV 40.

  Then, if the WGV opening sensor 40a fails due to any factor, for example, the opening of the WGV 40 becomes unknown, and the processor 10 can not determine to which opening the WGV 40 is controlled. Then, if the processor 10 continues the valve closing operation, for example, although the WGV 40 is closed, the probability that the component such as the motor of the electric actuator is burnt increases.

  FIG. 4 is an explanatory view of a characteristic showing an example of an output voltage of the WGV opening degree sensor. As shown in FIG. 4, the output characteristics of the WGV opening sensor 40a are such that the output voltage is low when the WGV 40 is fully closed and is linear when the WGV 40 is fully open so that the output voltage is high. It has become. However, the opposite characteristics may be obtained. Therefore, if the output voltage is associated with the opening degree of WGV 40, the opening degree of WGV 40 can be detected from the output voltage. The processor 10 temporarily stores, for example, the opening degree detected during operation in the RAM 11.

  In the present embodiment, when the WGV opening sensor 40a is shorted or disconnected and becomes an abnormal state, for example, even if the processor 10 tries to control the WGV 40 from the closed to the open side, the output characteristic is a broken line A or a broken line It is fixed to the value shown in B. Therefore, the processor 10 can diagnose the presence or absence of a failure of the WGV opening sensor 40a. Therefore, if no failure occurs, the processor 10 writes, for example, a value (0) indicating that the flag for failure diagnosis (hereinafter referred to as "failure diagnosis flag") is off in the RAM 11, and a failure occurs. For example, a value (1) indicating that the fault diagnosis flag is on is written in the RAM 11. Thereby, the processor 10 can diagnose the presence or absence of a failure of the WGV opening sensor 40a. Here, when a failure occurs, if the WGV 40 is forcibly opened to suppress the supercharging pressure, as described above, there is a concern that the engine torque will be insufficient and the drivability may be reduced.

  Therefore, in the present embodiment, as described in detail in the following description of the operation, when the WGV opening sensor 40a breaks down, a sufficient boost pressure is secured even in the low speed rotation region, and the necessary engine torque is Execute the obtained control.

[Description of operation]
Next, as an example of the control method of the internal combustion engine in the present embodiment, first, an outline of control of the engine 30 will be described. In the present embodiment, when the WGV opening sensor 40a breaks down, control for parallel processing of driving of the WGV 40 and supercharging pressure control is executed.

  As an outline of control of the engine 30, for example, the ECU 1 reads the intake air amount Q from the intake air amount sensor 23, reads the rotational speed Ne from the rotational speed sensor 51, and calculates the intake air amount Q and the rotational speed Ne. Based on the calculated basic fuel injection amount according to the operating state of the engine 30. Further, the ECU 1 further reads the atmospheric pressure (absolute pressure) from the atmospheric pressure sensor 52, reads the water temperature Tw from the water temperature sensor 50, and obtains a fuel injection amount obtained by correcting the basic fuel injection amount with the atmospheric pressure and the water temperature Tw.

  Then, the ECU 1 injects a fuel according to the fuel injection amount from the fuel injection valve 33 at a timing according to the operating state of the engine 30, operates the spark plug 35 appropriately, and ignites the mixture of fuel and air. Let At this time, the ECU 1 reads the air-fuel ratio from an air-fuel ratio sensor (not shown) and performs feedback control of the fuel injection valve 33 so that the air-fuel ratio in the exhaust approaches the stoichiometric air-fuel ratio. Hereinafter, the control processing in the case where the WGV opening sensor 40a breaks down will be described in detail.

  FIG. 5 is an explanatory view showing an example of a timing chart of control processing in the present embodiment. In FIG. 5, the horizontal axis indicates time. FIG. 5A shows the state of the result of failure diagnosis with the failure diagnosis flag turned on and off.

  FIG. 5 (b) shows an example of the driving state of the WGV 40. The vertical axis indicates the duty ratio [%] of the drive of the WGV 40, and expresses the amount of operation for opening and closing the WGV 40 by the processor 10 via the electric actuator (not shown). The processor 10 opens and closes the WGV 40 in accordance with the operation amount from the open side (100 [%]) to the close side (−100 [%]). In addition, in FIG.5 (b), it will not fully open if an operation amount does not become 100 [%], and does not fully close if an operation amount does not become -100 [%].

  In the present embodiment, as a method of controlling the WGV 40 in a failure state of the WGV opening sensor 40 a (hereinafter referred to as “sensor failure state”), when a failure occurs, the WGV 40 is first fully closed. That is, when the WGV opening sensor 40a breaks down, it is impossible to detect the subsequent opening. Therefore, the processor 10 may use another sensor that functions properly, for example, to completely close the WGV 40 from the degree of opening immediately before failure and the actual supercharging pressure in the intake pipe 21 to maintain the valve closed state. The possible time (hereinafter referred to as "valve closing transition time") is estimated as ΔT1. For example, in FIG. 5B, ΔT1 is ΔT1 = (t2−t1). In this case, the processor 10 executes control to set the duty ratio to the set value D2 (hereinafter, referred to as “D2”) during ΔT1.

  In the present embodiment, based on the operating characteristics of the WGV 40, ΔT1 is determined in advance by experiment from the relationship between the opening degree and the actual supercharging pressure, and the determined values are tabulated and stored in the flash memory 12 It is also good. ΔT1 may be, for example, a time that is recognized as the WGV 40 shifts from the fully open state to the fully closed state.

  Then, in the present embodiment, after the passage of ΔT1, the duty ratio is controlled in a sawtooth waveform to maintain the valve closing and for the heat countermeasure, and shift to the set value D1 (hereinafter referred to as “D1”) in a constant cycle. Control. That is, as shown in FIG. 5B, the processor 10 controls the duty ratio to monotonously increase up to the set value D0 (hereinafter referred to as “D0”) in accordance with a predetermined cycle, and D0 (0 [%] , And the process of setting the duty ratio to D1 is repeated. Note that D1 is an example, and it may be D2 as long as the duty ratio can be controlled in a sawtooth shape. That is, by controlling the duty ratio in a sawtooth shape, burning of parts such as a motor and the like in the electric actuator can be avoided. The specific flow of processing will be described with reference to the flowchart shown in FIG.

  Further, FIG. 5C shows an example of the supercharging pressure control in the case where the WGV opening degree sensor 40a fails, and the vertical axis shows the supercharging pressure. The graph shown in FIG. 5C shows the supercharging upper limit value p1 indicating the upper limit of the supercharging pressure, the target supercharging pressure p2 in the normal state, the target supercharging pressure p3 in the sensor failure state, and the actual supercharging pressure p4. ing. The target boost pressure p2 in the normal state corresponds to the first target boost pressure, and the target boost pressure p3 in the sensor failure state corresponds to the second target boost pressure. The processor 10 also controls the second target boost pressure lower than the first target boost pressure by a predetermined value (Δp = p2-p3) in the sensor failure state.

  Further, the graph shown in FIG. 5D shows an example of the driving state of the throttle valve 28. The opening degree of the throttle valve 28 based on the accelerator position sensor (APS) request and the opening degree of the throttle valve 28 based on the supercharging pressure control request are set, for example, in the direction (select low) from the viewpoint of safety. It is desirable to do. Further, for the control of the throttle valve 28 based on the supercharging pressure control request, it is desirable from the viewpoint of safety that pressure rising side speed <pressure falling side speed. The specific process flow shown in FIGS. 5C and 5D will be described in conjunction with the flowchart shown in FIG. FIG. 5E shows an example of the driving state of the ABV 26. The vertical axis indicates the open / close state.

  FIG. 6 is a flowchart showing an example of drive processing of the WGV in the present embodiment. In response to the activation of the ECU 1, the processor 10 of the ECU 1 repeatedly executes this flowchart at regular intervals (for example, on the order of milliseconds).

  Step S101: The processor 10 diagnoses whether or not a failure has occurred in the WGV opening sensor 40a. If a failure has not occurred (step S101: No), the processor 10 turns off the failure diagnosis flag, and ends the flowchart shown in FIG. On the other hand, when a failure has occurred (step S101: Yes), the processor 10 turns on the failure diagnosis flag and shifts to the processing of step S102. FIG. 5A exemplifies a state in which a failure occurs at time t1 from the off state (normal state) of the failure diagnosis flag and changes to the on state (sensor failure state).

  Step S102: The processor 10 determines whether or not ΔT1 (valve closing transition time) has elapsed since the failure occurrence of the WGV opening sensor 40a. When detecting the occurrence of a failure, the processor 10 starts measuring the time from the occurrence of the failure. If ΔT1 has elapsed since the failure occurrence (step S102: Yes), the process proceeds to step S103. When ΔT1 has not elapsed from the occurrence of the failure (step S102: No), the process proceeds to the process of step S106 described later.

  Step S103: The processor 10 determines whether the duty ratio has reached D0. When it reaches D0 (step S103: Yes), it transfers to the process of step S105. When it does not reach D0 (Step S103: No), it shifts to processing of Step S104.

  Step S104: The processor 10 changes the duty ratio to drive the WGV 40 by making the duty ratio into a sawtooth waveform. Specifically, the processor 10 executes the closed drive of the WGV 40 by adding a preset increment (Δd) to the current duty ratio. Then, the processor 10 ends the processing of the flowchart illustrated in FIG.

  Step S105: The processor 10 sets the duty ratio to D1 and executes the closing drive of the WGV 40. Then, the processor 10 ends the processing of the flowchart illustrated in FIG.

Step S106: The processor 10 sets the duty ratio to D2 and executes the closing drive of the WGV 40. Then, the processor 10 ends the processing of the flowchart illustrated in FIG.
As described above, in the sensor failure state, the processor 10 repeats the processing of the flowchart shown in FIG. 6 to execute control so as to be the timing chart shown in FIG.

Next, the supercharging pressure control process will be described.
FIG. 7 is a flowchart showing an example of the supercharging pressure control process in the present embodiment.
Step S201: The processor 10 diagnoses whether or not a failure has occurred in the WGV opening sensor 40a as in the process of step S101 shown in FIG. When the failure has not occurred (step S201: No), the processing of the flowchart shown in FIG. 7 is ended. On the other hand, if a failure has occurred (step S201: Yes), the process proceeds to step S202.

  Step S202: The processor 10 executes a process for obtaining a target boost pressure. Specifically, the processor 10 determines the current target boost pressure based on the map shown in FIG. However, this target boost pressure is corrected in step S204, as necessary.

  Step S203: The processor 10 determines whether the value of the target boost pressure is higher than the value of the atmospheric pressure. Specifically, the processor 10 reads the value of the atmospheric pressure sensor 52, and determines whether or not the value of the target boost pressure obtained in step S202 is higher. If this determination condition is satisfied (step S203: Yes), the processor 10 proceeds to the process of step S204. If the determination condition is not satisfied (step S203: No), the pressure is lower than atmospheric pressure. Therefore, the process of the flowchart shown in FIG. 7 is ended without executing the supercharging pressure control after step S204 at the time of failure.

Step S204: The processor 10 executes a correction process of the target boost pressure. That is, the processor 10 corrects the target boost pressure to apply the target boost pressure (second target boost pressure) at the time of failure. In this case, the processor 10 sets the target boost pressure (second target boost pressure) in the sensor failure state, and sets the target boost pressure (first target boost pressure, FIG. It calculates | requires so that it may become a value by the side of low voltage | pressure rather than p2 shown to 5 (c), and correct | amends (refer p3 shown in FIG.5 (c)). This makes it possible to prevent the engine torque from becoming excessively large.
As a method of calculating the second target boost pressure, in addition to the processing for setting the value lower than the first target boost pressure, in order to further suppress a malfunction due to noise superposition, Not only the calculated second target supercharging pressure, but also a filtering process using a moving average may be executed.

  That is, the processor 10 adjusts the opening degree of the WGV 40 to control the actual boost pressure so as to converge to the target boost pressure (second target boost pressure). For convenience of explanation, hereinafter, the actual boost pressure will be referred to as an actual boost pressure p4 shown in FIG. 5C as an example. Here, by repeating the process of the flow chart shown in FIG. 7, even if the WGV opening sensor 40 a fails, the processor 10 operates the engine 30 in the supercharging pressure (actual supercharging pressure). Since the opening degree of the WGV 40 is controlled to converge to the second target boost pressure which is lower by a predetermined value than the first target boost pressure according to the above, it is possible to suppress the decrease in drivability.

  Step S205: The processor 10 executes a setting process of the supercharging upper limit value. Specifically, the processor 10 sets the supercharging upper limit value under the sensor failure state higher than the corrected target supercharging pressure (second target supercharging pressure, see p3 shown in FIG. 5C). (See p1 shown in FIG. 5 (c)).

  Step S206: The processor 10 executes a feedback control of the supercharging pressure (F / B) with the throttle valve 28. Specifically, processor 10 controls the throttle valve 28 when the actual boost pressure p4 reaches the second target boost pressure (see, for example, time t3 shown in FIG. 5C). The pressure is stabilized (see time t3 shown in FIG. 5 (d)).

  Step S207: The processor 10 determines whether the actual supercharging pressure p4 has reached the supercharging upper limit value. If the actual supercharging pressure p4 has reached the supercharging upper limit value (step S207: Yes), the processor 10 proceeds to the process of step S208 (time t4 shown as an example in FIG. 5C). On the other hand, when the actual supercharging pressure p4 has not reached the supercharging upper limit value (step S207: No), the processor 10 does not have to suppress the increase in the actual supercharging pressure p4, so the supercharging pressure in step S208 and subsequent steps. The control ends the processing of the flowchart shown in FIG. 7 without executing the control.

  Step S208: The processor 10 operates the ABV 26 to the fully open side, cuts the fuel, and operates the throttle valve 28 to the fully closed side in order to suppress a further increase with respect to the actual supercharging pressure p4. However, with regard to the process of step S208, the processor 10 repeats the process of the flowchart shown in FIG. 7 to operate the ABV 26 fully open and operate the throttle valve 28 fully closed.

  Step S209: The processor 10 determines whether or not the actual boost pressure p4 has changed to, for example, the atmospheric pressure or less. If the actual supercharging pressure p4 has changed to the atmospheric pressure or lower (step S209: Yes), the processor 10 proceeds to the process of step S210. On the other hand, when the actual supercharging pressure p4 is higher than the predetermined value (step S209: No), the processor 10 ends the processing of the flowchart shown in FIG. 7 without executing the supercharging pressure control of step S210 and subsequent steps.

  Step S210: The processor 10 resumes the fuel injection and returns to the state of normal control for controlling the opening degree of the throttle valve 28 according to the operating state of the engine 30.

  Step S211: The processor 10 determines whether or not the state in which the actual supercharging pressure p4 has changed below the atmospheric pressure has continued for a preset time. If the preset time has been continued (step S211: YES), the processor 10 proceeds to the process of step S212. On the other hand, when the time set in advance has not been continued (step S211: No), the processor 10 ends the processing of the flowchart shown in FIG. If the actual supercharging pressure p4 is equal to or lower than the atmospheric pressure, the processor 10 may skip the process of step S211 and shift to the process of step S212.

  Step S212: The processor 10 operates the ABV 26 to the fully closed side. Then, the processor 10 ends the process of the flowchart illustrated in FIG.

  Here, when the boost pressure control process shown in FIG. 7 is summarized, the processor 10 repeats the process of the flowchart shown in FIG. 7 to obtain the result of the graph of FIG. 5C as an example. As shown in FIG. 5C, at time t3, when the actual boost pressure p4 reaches the target boost pressure under the sensor failure state, the processor 10 controls the throttle valve 28 to set the actual excess pressure. The feed pressure p4 is stabilized. Subsequently, at time t4, when the actual supercharging pressure p4 reaches the supercharging upper limit value, the processor 10 controls the ABV 26 to the fully open side, cuts the fuel, closes the throttle valve 28, and the actual supercharging pressure. A process of decreasing p4 is executed (see time t4 shown in FIG. 5 (d)). Furthermore, after the pressure (supercharging pressure) in the intake pipe 21 becomes atmospheric pressure at time t5, for example, the processor 10 fully closes the ABV 26 at time t6 after the elapse of a preset setting time (ΔT4). Execute the process to

  That is, if the WGV opening sensor 40a fails, feedback (F / B) of the supercharging pressure can not be performed based on the normal control by the WGV 40. Therefore, as described in step S206, the throttle valve 28 Feed pressure feedback (F / B) control processing is executed. Here, closing the throttle valve 28 means that the amount of intake air is reduced, so the flow rate of exhaust gas is reduced, and as a result, the supercharging pressure is reduced. On the other hand, opening the throttle valve 28 means that the amount of intake air is increased, so the flow rate of exhaust gas is increased, and as a result, the supercharging pressure is increased.

  The processor 10 may gradually increase the predetermined value (the suppression amount of the decrease in the actual boost pressure p4: Δp = (p2-p3)) according to the increase in the rotation speed of the engine 30. That is, the actual boost pressure p4 may be converged to the second target boost pressure by increasing the width of Δp as the rotational speed of the engine 30 increases. Even with such a control method, it is possible to suppress the decrease in drivability while avoiding unexpected acceleration according to the rotation speed of the engine 30.

  As described above, according to the present embodiment, for example, in the case of an automobile equipped with a downsizing engine, when the WGV opening sensor 40a breaks down, for example, supercharging pressure is also prevented in a low speed rotation region while avoiding unexpected acceleration. To realize the control that can obtain the required engine torque. Thereby, according to this embodiment, when sensors, such as WGV opening degree sensor 40a, fail, a fall of operativity can be controlled. In the present embodiment, as a supercharger, for example, it may be applied to a variable geometry (VG (Variable Geometry)) turbocharger.

  Next, first and second modified examples of the drive processing of the WGV 40 in the present embodiment will be described. The same components as those in the above-described embodiment are denoted by the same reference numerals and descriptions thereof will be omitted, and differences will be mainly described in detail. In the driving process of the WGV 40 described above, controlling the WGV 40 to fully close is given top priority. However, it is needless to say that this duty ratio is a level which does not burn parts such as the motor of the electric actuator. Here, in the first modified example, control is performed in which a duty ratio smaller than the duty ratio (the level of D1 shown in FIG. 5B) in the WGV 40 described above is continuously applied for a predetermined time. Even with such a method, similar effects can be obtained. The details will be described below.

  FIG. 8 is a flowchart showing a first modification. FIG. 9 is an explanatory view showing an example of a timing chart of the first modified example. The horizontal axis shows time, and the vertical axis is the same as FIG. 5 (b).

  Step S301: The processor 10 diagnoses whether or not a failure has occurred in the WGV opening sensor. If a failure has not occurred (step S301: No), the processor 10 turns off the failure diagnosis flag and ends the flowchart shown in FIG. On the other hand, when a failure has occurred (step S301: Yes), the processor 10 turns on the failure diagnosis flag and shifts to the process of step S302.

  Step S302: The processor 10 determines whether or not ΔT1 (valve closing transition time) has elapsed since the failure occurrence. When it passes (Step S302: Yes), it shifts to processing of Step S303. If it has not elapsed (step S302: No), the process proceeds to step S304.

  Step S303: The processor 10 sets the duty ratio to the set value D3 (hereinafter, referred to as "D3"). Then, the processor 10 executes the closing drive of the WGV 40 with this duty ratio, and ends the processing of the flowchart shown in FIG.

  Step S304: The processor 10 sets the duty ratio to a set value D4 (hereinafter, referred to as "D4"). Note that D4 shown in FIG. 9 may be, for example, at the same level as D2 shown in FIG. 5 (b). Then, the processor 10 executes the closing drive of the WGV 40 with this duty ratio, and ends the processing of the flowchart shown in FIG.

  As described above, according to the first modification, the timing chart shown in FIG. 9 is obtained as an example by repeating the process of the flowchart shown in FIG. Therefore, in the first modified example, when the sensor such as the WGV opening sensor 40a fails, the processor 10 changes the duty ratio to D3 and maintains it after ΔT1 elapses, thereby lowering the drivability. The supercharging pressure control process can be executed to suppress.

  Next, a second modification will be described. In the second modification, when the failure of the WGV opening sensor 40a occurs, the opening of the WGV 40 is controlled in a feedforward manner. This is because it is difficult to control the opening of the WGV 40 in a feedback manner. Specifically, when the WGV opening sensor 40a breaks down, the processor 10 leads to a predetermined F / S (Fale / Safe) opening. Note that the F / S opening degree is an experimental determination of an opening degree compatible with suppression of unexpected acceleration (UA), suppression of excessive supercharging, and maintenance of limp home operation. In the embodiment described above, the fully-closed state of the electronically controlled WGV 40 is maintained, but in the second modification, the WGV 40 is driven to close based on the experimentally determined opening for F / S. After opening, consider the case of opening the valve for a predetermined time as needed.

  FIG. 10 is an explanatory view showing an example of a timing chart in the second modified example. Similar to FIG. 5A, FIG. 10A shows the state of the result of the fault diagnosis with the fault diagnosis flag turned on and off. FIG. 10 (b) shows the state of a flag for determining the low pressure of the intake pipe pressure (hereinafter referred to as "low pressure determination flag"), and the processor 10 determines the low pressure if the pressure in the intake pipe 21 is lower than a predetermined pressure. Turn on the flag. FIG. 10C shows the duty ratio [%] of the drive of the WGV 40 as in FIG. 5C.

  In the second modification, as a precondition, when a failure occurs in the WGV opening sensor 40a, the processor 10 first controls the duty ratio to drive the WGV 40 closed during ΔT1 (valve closing transition time). D6 (see FIG. 10C) is applied as the duty ratio. Next, the processor 10 controls the WGV 40 to the open side after the elapse of ΔT1, for example, to maintain the target boost pressure (the second target boost pressure), the time for shifting to the F / S opening degree (hereinafter referred to It is referred to as "F / S opening transition time".) It leads to the F / S opening. That is, the processor 10 controls the duty ratio to D5 (see FIG. 10C). For example, in FIG. 10C, ΔT2 (F / S opening shift time) is ΔT2 = (t3−t2). This ΔT 2 is, for example, a value obtained in advance by experiment, and is stored in the flash memory 12.

  Furthermore, after the elapse of ΔT2, the processor 10 controls the duty ratio to maintain the F / S opening degree, sets D0 (0 [%]), and turns off the drive of the WGV 40. Control processing (hereinafter referred to as “WGV driving cycle processing”) is executed.

  When the WGV 40 moves to the open side due to some influence, the processor 10 executes the process of returning to the F / S opening again. Specifically, when the state of low pressure determination (the on state of the low pressure determination flag) continues for a predetermined time (ΔT3), the processor 10 executes the WGV drive cycle process to drive the WGV 40. The flow of the actual processing will be described later using the flowchart shown in FIG.

  FIG. 11 is a flowchart showing an example of the second modification. The processor 10 starts the flowchart shown in FIG. 11 triggered by the activation of the ECU 1 and repeatedly executes, for example, every time this flowchart is ended. The flowchart shown in FIG. 11 corresponds to the timing chart shown in FIG. First, the process in which the failure diagnosis flag is switched from off to on and the first WGV driving cycle is executed will be described.

  In step S401, the processor 10 diagnoses whether or not a failure has occurred in the WGV opening sensor 40a as in the process of step S301 shown in FIG. If a failure has not occurred (step S401: No), the processor 10 turns off the failure diagnosis flag, and ends the flowchart shown in FIG. On the other hand, if a failure has occurred (step S401: Yes), the processor 10 turns on the failure diagnosis flag and shifts to the process of step S402.

  The processor 10 executes the pressure determination of the intake pipe 21 in step S402. Specifically, the processor 10 determines the target boost pressure, and determines the presence or absence of a low pressure (below a predetermined pressure) based on whether the difference between the target boost pressure and the actual boost pressure is higher than a preset threshold. Do. More specifically, the processor 10 reads the value of the actual supercharging pressure (supercharging pressure P) output by the supercharging pressure sensor 27, and the difference with the value of the target supercharging pressure (second target supercharging pressure) The low pressure determination is performed based on whether or not the absolute value of (| target boost pressure−actual boost pressure |) is higher than a preset threshold value. As a result, if the pressure in the intake pipe 21 is lower than or equal to the predetermined pressure (step S402: Yes), the processor 10 proceeds to the process of step S403 as the low pressure determination, and if the pressure in the intake pipe 21 is higher than the predetermined pressure Step S402: No), the process proceeds to step S408.

  Here, when the failure diagnosis flag is switched on in FIG. 10A, since the low pressure determination flag is off in FIG. 10B, the process proceeds to step 408 and the processor 10 The determination is cleared, and the process proceeds to step S409.

  The processor 10 sets the timer (T3) to clear in step S409. In order to make the description easy to understand, when repeating the flow chart shown in FIG. 11, the processor 10 performs the process of determining the passage of time when each timer (T1 to T3) is already set to clear (step S405). , S411, and S415) are processed as No determination. In addition, when the timer (T1 to T3) is already set to clear in steps S409, S412, and S416, the processor 10 skips the process simply by passing through. Furthermore, when the timer (T1 to T3) has already started counting in steps S404, S416, and S413, the processor 10 skips the process simply by passing since it is currently counting.

  When the process flows from step S409 to step S405, the processor 10 proceeds to step S410 because the timer (T3) is set to clear. In step S410, the processor 10 determines whether it is the timing for the determination of the diagnosis failure of WGV. Here, this step 410 is executed for the first time at the timing when the failure diagnosis flag is switched on at t1 in FIG. 10A, in other words, since it is the timing of the determination establishment, the process proceeds to step S406. . Thereafter, in the process of step S410, in FIG. 10A, since the failure diagnosis flag is maintained in the on state, the processor 10 determines that it is not the timing of determination establishment (step S410: No), step It will progress to S411.

  Here, the processor 10 starts counting the timer (T1) when it proceeds to step S406 at the timing when the determination failure of the WGV diagnosis is established (step S410: Yes), and starts WGV 40 during ΔT1 in step S407. D6 is applied as a duty ratio for close driving (see t1 to t2 in FIG. 10C). Then, the processor 10 ends the processing of the flowchart shown in FIG. 11 and starts the processing of this flowchart again. In this case, as apparent from the timing chart of FIG. 10, this processor 10 performs step S401 (Yes determination) → S402 (No determination) → S408 → S409 → S405 (No determination) → as processing indicating that ΔT1 is being counted. A series of processes of S410 (No determination) → S411 (No determination) → S415 (No determination) are repeated. When the timer (T1) has passed ΔT1 (step S411: Yes), the process proceeds to step S412 (see t2 in FIG. 10C).

  Then, the processor 10 clears the timer (T1) in step S412, and starts counting of the timer (T2) in step S413. Then, in step S414, the processor 10 controls the duty ratio to D5 in order to open drive the WGV 40 (see t2 to t3 in FIG. 10C), and ends the processing of the flowchart illustrated in FIG. The processing of this flowchart is started. In this case, as apparent from the timing chart of FIG. 10, the processor 10 performs step S401 (Yes determination) → S402 (No determination) → S408 → S409 → S405 (No determination) → S410 as processing indicating that ΔT2 is being counted. A series of processes (No determination) → S411 (No determination) → S415 (No determination) are repeated. When the timer (T2) has passed ΔT2 (step S415: Yes), the process proceeds to step S416 (see t3 in FIG. 10C). Then, the processor 10 clears the timer (T2) in step S416, controls the duty ratio in step S417, sets D0 (0 [%]), and turns off the driving of the WGV 40. From the above, the first WGV driving cycle process is completed.

  Next, when the processing of this flowchart is started again, the processor 10 proceeds to step S401 (Yes determination) → S402 (step S402) until the pressure in the intake pipe 21 becomes lower than the predetermined pressure (the low pressure determination flag is on). No determination) → S408 → S409 → S405 (No determination) → S410 (No determination) → S411 (No determination) → S415 (No determination) a series of processing is repeated. When the pressure in the intake pipe 21 becomes lower than or equal to the predetermined pressure (step S402: Yes), the processor 10 determines the low pressure in step S403 (the low pressure determination flag is on), and counts the timer (T3) in step S404. Start (see t4 in FIG. 10 (c)). Subsequently, the processor 10 executes S405 (No determination) → S410 (No determination) → S411 (No determination) → S412 (No determination), and ends the processing of the flowchart shown in FIG. Start processing In this case, the processor 10 proceeds to step S401 (Yes determination) → S402 (Yes determination) → S403 → S404 → S405 (No determination) → as processing indicating that ΔT3 is being counted until the timer (T3) passes ΔT3. A series of processes of S410 (No determination) → S411 (No determination) → S415 (No determination) are repeated. Then, when the timer (T3) has passed ΔT3 (step S405: Yes), the processor 10 starts counting of the timer (T1) again in step S406 in order to execute the WGV driving cycle process, and step S407. Then, D6 (see t5 in FIG. 10C) is applied with the WGV 40 as the duty ratio for close driving during ΔT1.

  Then, the processor 10 ends the processing of the flowchart shown in FIG. 11 and starts the processing of this flowchart again. In this case, when the pressure in the intake pipe 21 is not lower than the predetermined pressure in step S402, the processor 10 clears the low pressure determination in step S408 (the low pressure determination flag is off), and in step S409 the timer (T3) clear. The subsequent processing repeats the WGV driving cycle processing described above.

  From the above, in the driving state of the WGV 40 in the second modification, if the WGV opening sensor 40a breaks down, feedback (F / B) control can not be performed, but the opening of the electronically controlled WGV 40 in a feedforward manner. Can be controlled. That is, when the WGV opening sensor 40a fails, the processor 10 repeatedly executes the WGV driving cycle process as necessary.

  As a result, also in the second modified example, when the WGV opening degree sensor 40a breaks down, the decrease in supercharging pressure is suppressed, so that the decrease in drivability can be suppressed. Furthermore, in the second modification, it is possible to achieve both suppression of unexpected acceleration (UA), suppression of excessive supercharging, and maintenance of limp home operation.

[Supplementary matter of the above embodiment]
(A) The control means may set the second target boost pressure higher than the atmospheric pressure and lower than the first target boost pressure. This makes it possible to prevent the engine torque from becoming excessively large.
(B) The control means may set the supercharging upper limit value higher than the first target supercharging pressure by a predetermined value. Thus, the upper limit value of supercharging in the mechanical waste gate valve is uniquely determined structurally, but in the case of the electronically controlled waste gate valve, it can be set according to the first target supercharging pressure. Therefore, it is possible to control the supercharging pressure so as to converge to the second target supercharging pressure while changing the supercharging upper limit value according to the first target supercharging pressure.

  As mentioned above, although embodiment indicated to this matter was explained using a specification, a drawing, etc., art of this indication is not limited to the above-mentioned embodiment, and various change in the range which does not deviate from the meaning of the present invention Is possible.

1 ... ECU
21: Intake pipe 24: Turbocharger 26: ABV
28: Throttle valve 30: Engine 40: WGV
40a ... WGV opening sensor

Claims (2)

Adjusting means for adjusting the supercharging pressure of the supercharger;
When the sensor for detecting the operating state of the adjusting means fails, the charging pressure converges to a second target charging pressure lower by a predetermined value than the first target charging pressure according to the operating state of the internal combustion engine. Control means for controlling the adjusting means ;
A control device for an internal combustion engine, wherein the control means gradually increases the predetermined value according to an increase in the rotational speed of the internal combustion engine. The supercharger is a turbocharger,
The adjustment means is a waste gate valve attached to the turbocharger,
The sensor is an opening degree sensor that detects the opening degree of the waste gate valve, and
The control device for an internal combustion engine according to claim 1, wherein the control means controls the waste gate valve to a closed side to suppress a decrease in the supercharging pressure.