JP2007009877A - Abnormality diagnostic device for supercharging pressure control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect abnormalities of change characteristics of actual supercharging pressure with respect to change in a TCV (turbine control valve) control duty value, in a system to control actual supercharging pressure of intake air supercharged by a supercharger by performing duty control of current-carrying to a TCV and controlling an opening of a WGV (waste gate valve). <P>SOLUTION: When an engine 11 is in a steady operation condition, the TCV control duty value is forcibly changed e.g. by a predetermined amount from 0% (value corresponding to full opening of the WGV 36) to 100% (value corresponding to full closing of the WGV 36). A deviation between target supercharging pressure (value corresponding to actual supercharging pressure in a normal system) corresponding to the TCV control duty value and actual supercharging pressure is calculated each time the TCV control duty value is changed by the predetermined amount. This deviation is compared with an abnormality determination value to determine presence/absence of the abnormality (decline in linearity etc.) in the change characteristics of the actual supercharging pressure relative to the change in the TCV control duty value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis device for a supercharging pressure control system that controls a supercharging pressure of intake air supercharged by a supercharger.

  Conventionally, some internal combustion engines mounted on vehicles are equipped with an exhaust turbine-driven supercharger (so-called turbocharger) for the purpose of increasing output. A general configuration of this exhaust turbine driven supercharger is to connect an exhaust turbine provided in an exhaust passage of an internal combustion engine and a compressor provided in an intake passage to rotationally drive the exhaust turbine with the kinetic energy of the exhaust gas. The compressor is driven to rotate to supercharge intake air.

  As a technique for controlling the supercharging pressure of the intake air supercharged by this supercharger, as described in Japanese Patent Application Laid-Open No. 2000-345852, an exhaust bypass passage that bypasses the exhaust turbine. Is provided with a WGV (waste gate valve), and the amount of exhaust gas supplied to the exhaust turbine by feedback control of the opening of the WGV so that the actual boost pressure detected by the boost pressure sensor matches the target boost pressure. By controlling the above, there is one in which the actual supercharging pressure is controlled to the target supercharging pressure by controlling the rotational speed of the compressor that rotates integrally with the exhaust turbine.

Further, as an abnormality diagnosis technique of this supercharging pressure control system, as described in Patent Document 1, the deviation between the actual supercharging pressure and the target supercharging pressure and the feedback correction calculated based on this deviation In some cases, the amount is compared with a predetermined determination value to determine whether or not there is a failure in the supercharging pressure control component.
JP 2000-345852 A

  By the way, as shown in FIG. 3, in a normal supercharging pressure control system, an actual excess is detected with respect to a change in the WGV control signal (control duty value Duty of the solenoid valve driving the WGV) for controlling the opening degree of the WGV. The supply pressure changes with a certain degree of linearity (linearity). For example, in a supercharging pressure control system in which foreign matter such as oil adheres to the solenoid valve that drives the WGV, the WGV control signal The change characteristic of the actual supercharging pressure with respect to the change may change, and the linearity of the change characteristic of the actual supercharging pressure with respect to the change of the WGV control signal may decrease. When such an abnormality occurs, the controllability of the supercharging pressure control may be reduced.

  However, the abnormality diagnosis technique disclosed in Patent Document 1 does not take into account the change characteristic of the actual supercharging pressure with respect to the change of the WGV control signal. Therefore, an abnormality in the change characteristic of the actual supercharging pressure (such as a decrease in linearity) is detected. There is a drawback that it cannot be detected.

  The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to provide an abnormality diagnosis device for a supercharging pressure control system capable of detecting an abnormality in the change characteristic of the actual supercharging pressure. It is to provide.

  In order to achieve the above object, an invention according to claim 1 is directed to a supercharger that drives a compressor by an exhaust turbine provided in an exhaust passage of an internal combustion engine to supercharge intake air, and an exhaust that bypasses the exhaust turbine. A waste gate valve (hereinafter referred to as “WGV”) that opens and closes the bypass passage, and controls the actual supercharging pressure of the intake air supercharged by the supercharger by controlling the opening of the WGV In the pressure control system, the WGV control signal for controlling the opening degree of the WGV is forcibly changed when the internal combustion engine is in a steady operation state, and the change in the WGV control signal is changed based on the actual supercharging pressure at that time. Whether or not there is an abnormality in the change characteristic of the actual supercharging pressure is determined.

  If the WGV control signal is forcibly changed when the internal combustion engine is in a steady operation state, and the behavior of the actual boost pressure at that time is monitored, the change characteristic of the actual boost pressure with respect to the change of the WGV control signal is evaluated. It is possible to determine whether or not there is an abnormality in the change characteristic of the actual supercharging pressure with respect to a change in the WGV control signal (such as a decrease in linearity). As a result, when an abnormality in the change characteristic of the actual supercharging pressure occurs, the abnormality can be detected at an early stage.

  As in the abnormality diagnosis of the present invention, when the WGV control signal is forcibly changed when the internal combustion engine is in a steady operation state to change the opening of the WGV, the actual supercharging pressure changes and the intake air amount changes. Therefore, torque fluctuation may occur and drivability may be reduced.

  Therefore, the present invention is preferably applied to a system that executes torque demand control for calculating a control parameter of the internal combustion engine so as to realize the required torque of the internal combustion engine, as in claim 2. In this way, even when the WGV control signal is forcibly changed during abnormality diagnosis to change the opening of the WGV, a torque change due to the change in the opening of the WGV does not occur (that is, the required torque Torque parameter control automatically corrects internal combustion engine control parameters (for example, target throttle opening, etc.), preventing torque fluctuations and improving drivability Can be made.

  Further, in the case of a system that does not execute torque demand control, torque correction that corrects the control parameter of the internal combustion engine so as to suppress torque fluctuation when the WGV control signal is forcibly changed is performed. It is better to do it. In this way, even in the case of a system that does not execute torque demand control, when the WGV control signal is forcibly changed at the time of abnormality diagnosis and the WGV opening is changed, the change in the opening of the WGV is caused. By correcting a control parameter (for example, a target throttle opening degree) of the internal combustion engine so as to cancel the torque change, it is possible to prevent the occurrence of torque fluctuation and improve drivability.

  By the way, in order to reliably detect an abnormality in the change characteristic of the actual supercharging pressure with respect to the change of the WGV control signal, the change region when the WGV control signal is forcibly changed is made as wide as possible (for example, the opening degree of the WGV is reduced). It is preferable to change from near fully closed to near fully open. However, when the internal combustion engine is in the low load region or the low rotation speed region, the throttle opening is already small, and there is not enough room left to correct the throttle opening, so the torque when the WGV opening is reduced. There is a possibility that the increase cannot be canceled out by the torque decrease due to the throttle opening decrease correction. On the other hand, when the internal combustion engine is in a high load region or a high rotation speed region, the throttle opening is already large, and there is not enough room left to increase the throttle opening, so the torque when the WGV opening is increased. There is a possibility that the decrease cannot be canceled out by the torque increase due to the increase correction of the throttle opening.

  Taking these circumstances into consideration, as shown in claim 4, when the internal combustion engine is in a steady operation state in a medium load / medium rotational speed region, the WGV control signal is forcibly changed to change the actual supercharging pressure. It is advisable to execute the abnormal diagnosis. When the internal combustion engine is in the middle load / medium speed range, the throttle opening is in the middle region and there is sufficient room to correct the throttle opening in both the increasing and decreasing directions. The torque increase when it is reduced can be canceled out with the torque decrease due to the throttle opening decrease correction, and the torque decrease when the WGV opening is increased is compensated for by the throttle opening increase correction. It is possible to cancel with an increase. This makes it possible to widen the change region of the WGV control signal (for example, to change the opening degree of the WGV from near fully closed to near fully open) while reliably preventing the occurrence of torque fluctuation during abnormality diagnosis. When an abnormality in the change characteristic of the actual supercharging pressure occurs, the abnormality can be reliably detected.

  The specific abnormality diagnosis method for the change characteristic of the actual supercharging pressure is a target supercharging pressure corresponding to the WGV control signal every time the WGV control signal is forcibly changed by a predetermined amount as in claim 5. It is preferable to determine whether there is an abnormality in the change characteristic of the actual supercharging pressure with respect to the change of the WGV control signal based on the deviation between the actual supercharging pressure and the actual supercharging pressure. If the system is normal, when the WGV control signal is forcibly changed to change the opening of the WGV, the actual supercharging pressure becomes almost the same as the target supercharging pressure corresponding to the WGV control signal. Every time the WGV control signal is forcibly changed by a predetermined amount, the deviation between the target boost pressure corresponding to the WGV control signal (a value corresponding to the actual boost pressure of a normal system) and the actual boost pressure is evaluated. For example, it is possible to accurately determine whether there is an abnormality in the change characteristic of the actual supercharging pressure with respect to a change in the WGV control signal.

  Alternatively, each time the WGV control signal is forcibly changed by a predetermined amount, the change characteristic of the actual supercharging pressure with respect to the change of the WGV control signal based on the change amount or change rate of the actual supercharging pressure. The presence or absence of an abnormality may be determined. Even in this case, it is possible to accurately determine whether there is an abnormality in the change characteristic of the actual supercharging pressure with respect to the change in the WGV control signal.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 (intake passage) of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. On the downstream side of the air flow meter 14, a compressor 30 of an exhaust turbine drive supercharger 28 described later and an intercooler 31 for cooling the intake air pressurized by the compressor 30 are provided. A supercharging pressure sensor 32 that detects an intake pressure upstream of the throttle valve 16 (hereinafter referred to as “supercharging pressure”) is provided downstream of the intercooler 31. Note that an intake air temperature sensor may be provided integrally with the supercharging pressure sensor 32. A throttle valve 16 whose opening is adjusted by the motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the supercharging pressure sensor 32. Yes.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pressure sensor 19 for detecting an intake pressure on the downstream side of the throttle valve 16 (hereinafter simply referred to as “intake pressure”) is provided in the surge tank 18. Is provided. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. A spark plug 22 is attached to each cylinder of the cylinder head of the engine 11, and the air-fuel mixture of each cylinder is ignited by spark discharge of each spark plug 22.

  On the other hand, the exhaust pipe 23 of the engine is provided with an upstream catalyst 24 such as a three-way catalyst for purifying exhaust gas and a downstream catalyst 25 at a predetermined interval in one catalyst case. A first exhaust gas sensor 26 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas is provided upstream of the upstream catalyst 24, and the upstream catalyst 24 and the downstream catalyst are detected. 25, a second exhaust gas sensor 27 is provided.

  An exhaust turbine driven supercharger 28 is mounted on the engine 11. In the supercharger 28, an exhaust turbine 29 is disposed upstream of the first exhaust gas sensor 26 in the exhaust pipe 23, and a compressor 30 is disposed between the air flow meter 14 and the throttle valve 16 in the intake pipe 12. ing. In the supercharger 28, an exhaust turbine 29 and a compressor 30 are connected, and the exhaust turbine 29 is rotationally driven by the kinetic energy of the exhaust gas, whereby the compressor 30 is rotationally driven to supercharge intake air. .

  Further, the intake pipe 12 is provided with an intake bypass passage 33 that bypasses the upstream side and the downstream side of the compressor 30 on the upstream side of the throttle valve 16. The intake bypass passage 33 is opened and closed in the middle of the intake bypass passage 33. An air bypass valve 34 is provided.

  On the other hand, the exhaust pipe 23 is provided with an exhaust bypass passage 35 that bypasses the upstream side and the downstream side of the exhaust turbine 29, and a waste gate valve (hereinafter referred to as “open”) that opens and closes the exhaust bypass passage 35 in the middle of the exhaust bypass passage 35. 36 (denoted as “WGV”). The WGV 36 is configured such that the opening degree of the WGV 36 is controlled by controlling the diaphragm actuator 38 by duty-controlling the energization to a turbine control valve (hereinafter referred to as “TCV”) 37 constituted by an electromagnetic valve. It has become.

  A cooling water temperature sensor 39 that detects the cooling water temperature and a crank angle sensor 40 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 40, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 41. The ECU 41 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 21 according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  Further, as shown in FIG. 2, the ECU 41 executes torque demand control for controlling the throttle opening so as to realize the required torque according to the accelerator opening (depressing amount of the accelerator pedal) and the like as follows. Thus, it serves as a torque demand control means in the claims.

  First, a required torque is calculated by a map or a mathematical formula based on the accelerator opening, etc., and this required torque is converted into a required intake air amount. Based on the required intake air amount and the upper limit supercharging pressure, the target intake pressure is calculated by a map or a mathematical formula, and the target intake pressure and the required intake air amount are guarded with the upper limit guard value corresponding to the upper limit supercharging pressure. The final target intake pressure and the final required intake air amount are obtained by processing.

  Further, the target boost pressure is calculated by a map or a mathematical formula based on the atmospheric pressure detected by an atmospheric pressure sensor (not shown), the actual boost pressure detected by the boost pressure sensor 32, the upper limit boost pressure, and the like. At that time, when the driving mode is switched between the sport mode and the economy mode, a map or a mathematical expression of the target boost pressure is switched according to the driving mode.

  Thereafter, a target throttle opening for realizing the required intake air amount is calculated by a map or a mathematical formula based on the target boost pressure, the target intake pressure, the required intake air amount, the intake air temperature, etc., and the actual throttle opening is calculated. The throttle valve 16 is feedback-controlled so as to match the target throttle opening.

  Further, as shown in FIG. 2, the ECU 41 controls the supercharging pressure of the intake air supercharged by the supercharger 28 as follows. First, after calculating the target supercharging pressure by the above-described method, a TCV control duty value (TCV37 control) for realizing the target supercharging pressure by a map or a mathematical formula based on the target supercharging pressure and the engine speed, etc. Duty value) Duty is calculated. By controlling the opening of the WGV 36 by duty-controlling the TCV 37 with this TCV control duty value Duty, the exhaust gas flow supplied to the exhaust turbine 29 is controlled to rotate integrally with the exhaust turbine 29. The actual supercharging pressure is controlled to the target supercharging pressure by controlling the rotational speed of the compressor 30.

  Incidentally, as shown in FIG. 3, in a normal supercharging pressure control system, the actual supercharging pressure changes with a certain degree of linearity (linearity) with respect to the change in the TCV control duty value Duty. In the supercharging pressure control system in which foreign matters such as oil adhere to the TCV 37 that drives the TCV, the change characteristic of the actual supercharging pressure with respect to the change of the TCV control duty value Duty changes in a part of the region, and the TCV control duty value Duty In some cases, the linearity of the change characteristic of the actual supercharging pressure with respect to the change in the pressure drops. When such an abnormality occurs, the controllability of the supercharging pressure control may be reduced.

  Accordingly, the ECU 41 executes each routine for supercharging pressure control system abnormality diagnosis shown in FIGS. 4 to 7 to be described later, thereby setting the TCV control duty value Duty to 0% (for example, 0%) when the engine 11 is in a steady operation state. Each time the TCV control duty value Duty is changed by the predetermined amount a by forcibly changing the WGV 36 from the fully open equivalent value of the WGV 36 to 100% (equivalent value of the fully closed WGV 36), the TCV control duty value Duty is handled. The deviation ΔP between the target supercharging pressure Ptbp to be performed and the actual supercharging pressure Pabp is calculated, the absolute value of the deviation ΔP is compared with a predetermined abnormality judgment value TP, and the actual supercharging pressure with respect to the change in the TCV control duty value Duty The presence / absence of abnormality in the change characteristic of Pabp (decrease in linearity, etc.) is determined.

  If the system is normal, when the TCV control duty value Duty is forcibly changed to change the opening of the WGV 36, the actual supercharging pressure Pabp becomes equal to the target supercharging pressure Ptbp corresponding to the TCV control duty value Duty. Therefore, every time the TCV control duty value Duty is changed by a predetermined amount a, the target boost pressure Ptbp (a value corresponding to the actual boost pressure of a normal system) corresponding to the TCV control duty value Duty If the deviation ΔP from the supercharging pressure Pabp is compared with the abnormality determination value TP, it is possible to accurately determine whether there is an abnormality in the change characteristic of the actual supercharging pressure Pabp with respect to the change in the TCV control duty value Duty (such as a decrease in linearity). Can do.

  As in the abnormality diagnosis of the present embodiment, when the TCV control duty value Duty is forcibly changed when the engine 11 is in a steady operation state and the opening of the WGV 36 is changed, the actual boost pressure Pabp is changed and suction is performed. Since the air amount changes, torque fluctuation may occur. However, in this embodiment, since the torque demand control described above is executed, the TCV control duty value Duty is forcibly changed at the time of abnormality diagnosis. Even if the opening degree of the WGV 36 is changed, the target throttle opening degree is automatically corrected by torque demand control so that the torque change due to the opening degree change of the WGV 36 does not occur (that is, the required torque is maintained). Thus, the occurrence of torque fluctuation can be prevented.

  By the way, in order to reliably detect an abnormality in the change characteristic of the actual supercharging pressure Pabp with respect to a change in the TCV control duty value Duty, the change region when forcibly changing the TCV control duty value Duty is made as wide as possible (for example, It is preferable that the opening degree of the WGV 36 is changed from near fully closed to near fully open. However, when the engine 11 is in the low load region or the low rotation speed region, the throttle opening is already small, and there is not enough room left to correct the throttle opening, so the torque when the opening of the WGV 36 is reduced. There is a possibility that the increase cannot be canceled out by the torque decrease due to the throttle opening decrease correction. On the other hand, when the engine 11 is in a high load region or a high rotation speed region, the throttle opening is already large, and there is not enough room left to increase the throttle opening. Therefore, the torque when the opening of the WGV 36 is increased. There is a possibility that the decrease cannot be canceled out by the torque increase due to the increase correction of the throttle opening.

  Therefore, the ECU 41 forcibly changes the TCV control duty value Duty and performs abnormality diagnosis of the change characteristic of the actual boost pressure Pabp when the engine 11 is in a steady operation state in the medium load / medium rotational speed region. I have to. This is because when the engine 11 is in the middle load / medium rotational speed region, the throttle opening is in the intermediate region, and there is sufficient room for correcting the throttle opening in both the increasing and decreasing directions. The amount of torque increase when the opening of the WGV 36 is reduced can be surely canceled by the torque decrease due to the decrease correction of the throttle opening, and the torque decrease when the opening of the WGV 36 is increased This is because the torque can be canceled with certainty by the increase correction.

  The abnormality diagnosis of the supercharging pressure control system described above is executed by the ECU 41 according to each routine for supercharging pressure control system abnormality diagnosis shown in FIGS. Hereinafter, the processing content of each of these routines will be described.

[Normal determination routine]
The steady state determination routine shown in FIG. 4 is executed at a predetermined cycle while the ECU 41 is powered on. When this routine is started, first, at step 101, the engine rotational speed NE detected by the crank angle sensor 40 and the engine load Load (intake air amount or intake pressure) detected by the air flow meter 14 or the intake pressure sensor 19 are calculated. After the reading, the routine proceeds to step 102, where the engine speed change amount ΔNE (for example, the difference between the current value of the engine speed NE and the previous value) and the engine load change amount ΔLoad (for example, the current value of the engine load Load) The difference from the previous value is calculated.

  Thereafter, the routine proceeds to step 103, where it is determined whether or not the absolute value of the change amount ΔNE of the engine rotational speed is smaller than the steady state determination TNE value, and the absolute value of the change amount ΔLoad of the engine load is smaller than the steady state determination value TLoad. It is determined whether or not it is small.

  As a result, when it is determined that the absolute value of the engine speed change amount ΔNE is smaller than the steady-state determination value TNE and the absolute value of the engine load change amount Load is determined to be smaller than the steady-state determination value TLoad. Advances to step 104 and sets the steady state determination flag XStable to “1” which means that the engine 11 is in a steady operation state.

  On the other hand, if it is determined in step 103 that the absolute value of the change amount ΔNE of the engine rotation speed is equal to or greater than the steady determination value TNE, or the absolute value of the change amount ΔLoad of the engine load is the steady determination value TLoad. If it is determined as above, the routine proceeds to step 105, where the steady determination flag XStable is reset to “0” which means that the engine 11 is in a transient operation state.

  In this routine, it is determined whether or not the engine 11 is in a steady operation state based on the change amount of the engine speed and the change amount of the engine load. However, the present invention is not limited to this. It may be determined whether the engine 11 is in a steady operation state based on the amount of change, the amount of change in the required torque, the amount of change in the required intake air amount, the amount of change in the required intake pressure, etc. The method for determining whether or not is in a steady operation state may be changed as appropriate.

[WGV forced open / close mode determination routine]
The WGV forced opening / closing mode determination routine shown in FIG. 5 is executed at a predetermined cycle while the ECU 41 is powered on. When this routine is started, first, in step 201, it is determined whether or not the engine 11 is in a steady operation state depending on whether or not the steady determination flag XStable is set to “1”.

  As a result, when it is determined that the engine 11 is in the steady operation state (XStable = 1), the process proceeds to step 202, and the engine speed NE detected by the crank angle sensor 40 is within a predetermined range (MaxNE> NE> MinNE). ), It is determined whether or not the engine 11 is in the middle rotational speed region, and whether or not the intake air amount Q detected by the air flow meter 14 is within a predetermined range (MaxQ> Q> MinQ). To determine whether or not the engine 11 is in the middle load region.

  If it is determined in step 202 that the engine 11 is in the medium rotation speed region and it is determined that the engine 11 is in the medium load region, the process proceeds to step 203 where the WGV forced open / close mode flag XDiag is set. Is set to “1”, which means that the WGV forced opening / closing mode is permitted.

  On the other hand, if it is determined in step 202 that the engine 11 is not in the middle rotation speed region, or if it is determined that the engine 11 is not in the middle load region, the process proceeds to step 204 to force WGV The open / close mode flag XDiag is reset to “0” which means that it is not the WGV forced open / close mode.

[Error diagnosis execution flag operation routine]
The abnormality diagnosis execution flag operation routine shown in FIG. 6 is executed at a predetermined cycle while the ECU 41 is powered on. When this routine is started, first, at step 301, it is determined whether or not an IG switch (ignition switch) (not shown) has been switched from OFF to ON. When the IG switch is switched from OFF to ON, Proceeding to 302, the abnormality diagnosis execution flag XDone is reset to “0” which means that abnormality diagnosis of the supercharging pressure control system has not been executed during the current trip (while the IG switch is on).

[Supercharging pressure control system abnormality diagnosis routine]
The supercharging pressure control system abnormality diagnosis routine shown in FIG. 7 is executed at a predetermined cycle while the ECU 41 is turned on, and serves as abnormality diagnosis means in the claims. When this routine is started, first, in step 401, whether or not abnormality diagnosis of the boost pressure control system is not performed during the current trip, depending on whether or not the abnormality diagnosis execution flag XDone is reset to “0”. In the next step 402, it is determined whether or not the WGV forced opening / closing mode permits the WGV 36 to be forcibly opened / closed depending on whether or not the WGV forced opening / closing mode flag XDiag is set to “1”.

  If it is determined in step 401 that the abnormality diagnosis of the supercharging pressure control system has already been performed once during this trip (XDone = 1), or in step 402, the WGV forced switching mode is not set. If it is determined that (XDiag = 0), the process proceeds to step 403 without executing the processing related to abnormality diagnosis of the boost pressure control system after step 404, and the TCV control duty value Duty is set to the normal duty value Normal. Return or hold Duty. At that time, when returning the TCV control duty value Duty to the normal duty value Normal Duty from the duty value Diag Duty for WGV forcible opening / closing described later, the TCV control duty value Duty is smoothed and gradually processed at the normal time. It approaches the duty value Normal Duty.

  On the other hand, in step 401, it is determined that the abnormality diagnosis of the supercharging pressure control system has not been performed once during this trip (XDone = 0), and in step 402, the WGV forced open / close mode is set. When it is determined that (XDiag = 1), the processing related to abnormality diagnosis of the supercharging pressure control system after step 404 is executed as follows.

  First, in step 404, it is determined whether or not the initial determination flag XInitial has been reset to “0”. When starting the process relating to the abnormality diagnosis of the supercharging pressure control system, since the initial determination flag XInitial is reset to “0”, it is determined “Yes” in this step 404, the process proceeds to step 405, and the WGV After the forced opening / closing duty value Diag Duty is set to the initial value Initial (eg, 0%), the process proceeds to step 406, the initial determination flag XInitial is set to “1”, and the process proceeds to step 407.

  After the initial determination flag XInitial is set to “1” in step 406, it is determined as “No” in step 404, the processing in steps 405 and 406 is skipped, and the process proceeds to step 407.

  In the next step 407, the duty value Diag Duty for WGV forced opening / closing is increased by a predetermined amount a, and then the process proceeds to step 408, where the TCV control duty value Duty is set to the duty value Diag Duty for WGV forced opening / closing. As a result, the TCV control duty value Duty is forcibly increased by a predetermined amount a.

  Thereafter, the process proceeds to step 409, and after reading the actual supercharging pressure Pabp detected by the supercharging pressure sensor 32, the process proceeds to step 410, where the target supercharging pressure Ptbp corresponding to the TCV control duty value Duty (the normal system Read the value corresponding to the boost pressure). Thereafter, the process proceeds to step 411, and after calculating the deviation ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp, the process proceeds to step 412, where the absolute difference ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp is calculated. It is determined whether or not the value is larger than the abnormality determination value TP.

  As a result, if it is determined in step 412 that the absolute value of the deviation ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp is equal to or less than the abnormality determination value TP, the process proceeds to step 413 and the TCV control duty value It is determined whether or not Duty has reached an upper limit value MaxDuty (for example, 100%).

  If it is determined in step 413 that the TCV control duty value Duty is smaller than the upper limit value MaxDuty, the TCV control duty value Duty is forcibly set to a predetermined amount until the TCV control duty value Duty reaches the upper limit value MaxDuty. Every time the value a is increased, the process of determining whether or not the absolute value of the deviation ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp is larger than the abnormality determination value TP is repeated (steps 401 to 412).

  Before it is determined in step 413 that the TCV control duty value Duty has reached the upper limit value MaxDuty, in step 412, the absolute value of the deviation ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp is determined to be abnormal. If it is determined that the value is greater than the value TP, it is determined that there is an abnormality (change in linearity, etc.) in the change characteristic of the actual boost pressure Pabp with respect to the change in the TCV control duty value Duty, and the process proceeds to step 414 to determine abnormality. After the flag XFault is set to “1”, the process proceeds to step 415, the abnormality diagnosis execution flag XDone is set to “1”, and the duty value Diag Duty for WGV forced opening / closing is reset to “0” in the next step 416. At the same time, the initial determination flag XInitial is reset to “0”, and this routine ends.

  On the other hand, in step 412, the absolute value of the deviation ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp is not determined to be larger than the abnormality determination value TP. If it is determined that the duty value Duty has reached the upper limit value MaxDuty, it is determined that there is no abnormality (normal) in the change characteristic of the actual boost pressure Pabp with respect to the change in the TCV control duty value Duty, and the process proceeds to step 415. The abnormality diagnosis execution flag XDone is set to “1”, and in the next step 416, the duty value Diag Duty for forced opening / closing of the WGV is reset to “0”, and the initial determination flag XInitial is reset to “0”. This routine ends.

  In the present embodiment described above, every time the engine 11 is in a steady operation state, the TCV control duty value Duty is forcibly changed by a predetermined amount a and the TCV control duty value Duty is changed by the predetermined amount a. The absolute value of the deviation ΔP between the target boost pressure Ptbp corresponding to the control duty value Duty and the actual boost pressure Pabp is compared with the abnormality determination value TP, and the change in the actual boost pressure Pabp with respect to the change in the TCV control duty value Duty Since it is determined whether or not there is a characteristic abnormality (decrease in linearity, etc.), it is possible to accurately determine whether or not there is an abnormality in the change characteristic of the actual boost pressure Pabp, and an abnormality in the change characteristic of the actual boost pressure Pabp. When (such as a decrease in linearity) occurs, the abnormality can be detected early.

  In addition, in this embodiment, since torque demand control is executed, even if the TCV control duty value Duty is forcibly changed at the time of abnormality diagnosis and the opening degree of the WGV 36 is changed, the torque due to the opening change of the WGV 36 is changed. Torque demand control automatically corrects the target throttle opening, etc. so that no change occurs (that is, the required torque is maintained), and torque fluctuations can be prevented. Drivability can be improved.

  Further, in this embodiment, when the engine 11 is in the middle load / medium rotational speed region, the throttle opening is in the intermediate region, and a sufficient margin remains to correct the throttle opening in both the increasing direction and the decreasing direction. Therefore, paying attention to the fact that the torque change when the opening degree of the WGV 36 is changed can be canceled with certainty by the torque change due to the decrease correction or increase correction of the throttle opening, In the speed range, the TCV control duty value Duty is forcibly changed to perform abnormality diagnosis of the change characteristic of the actual boost pressure Pabp, so that torque fluctuations can be reliably generated during abnormality diagnosis. TCV control duty value Duty change range can be widened while preventing (opening of WGV 36 is changed from near fully closed to near fully open), and change in actual supercharging pressure Pabp When a characteristic abnormality occurs, the abnormality can be reliably detected.

  In the above embodiment, every time the TCV control duty value Duty is forcibly changed by a predetermined amount a, the deviation ΔP between the target boost pressure Ptbp and the actual boost pressure Pabp corresponding to the TCV control duty value Duty is determined as an abnormality. Compared with the value TP, it is determined whether or not there is an abnormality in the change characteristic of the actual boost pressure Pabp with respect to the change in the TCV control duty value Duty, but the abnormality determination method of the change characteristic of the actual boost pressure Pabp is changed as appropriate You may do it.

  For example, as shown in FIG. 8, after calculating the deviation ΔP between the actual boost pressure Pabp and the target boost pressure Ptbp in step 411, the process proceeds to step 411a and the previous deviation ΔP (i-1) and the current deviation are calculated. An integrated value ΔP [ΔP = ΔP (i−1) + ΔP (i)] obtained by integrating ΔP (i) is obtained, the absolute value of the integrated value ΔP is compared with the abnormality determination value TP, and the TCV control duty value Duty It may be determined whether or not there is an abnormality in the change characteristic of the actual boost pressure Pabp with respect to the change.

  In the routine of FIG. 8, the integrated value ΔP of the previous deviation ΔP (i−1) and the current deviation ΔP (i) is obtained, but the current deviation is calculated from the previous deviation twice or more. Alternatively, the integrated value ΔP from the start of the forced change of the TCV control duty value Duty to the current deviation may be obtained.

  Further, every time the TCV control duty value Duty is forcibly changed by a predetermined amount a, the amount or rate of change of the actual supercharging pressure Pabp is compared with the abnormality judgment value, and the actual supercharging with respect to the change of the TCV control duty value Duty. The presence or absence of an abnormality in the change characteristic of the pressure Pabp may be determined.

  In the above embodiment, the TCV control duty value Duty itself is forcibly changed. However, the TCV control duty value Duty may be changed by forcibly changing the target boost pressure Ptbp. .

  In the above embodiment, the present invention is applied to a system that executes torque demand control. However, in the case of a system that does not execute torque demand control, torque fluctuation when the TCV control duty value Duty is forcibly changed. Torque correction for correcting the control parameter of the engine 11 may be executed so as to suppress the engine torque. This function serves as torque correction means in the claims. In this way, even in the case of a system that does not execute torque demand control, when the TCV control duty value Duty is forcibly changed during abnormality diagnosis and the opening degree of the WGV 36 is changed, the opening degree of the WGV 36 is changed. By correcting the control parameter (for example, target throttle opening degree) of the engine 11 so as to cancel the torque change due to the change, occurrence of torque fluctuation can be prevented, and drivability can be improved.

  In the above embodiment, the present invention is applied to a system that controls the opening of the WGV 36 by controlling the TCV 37 (solenoid valve). However, the WGV configured by an electrically controllable actuator such as a solenoid valve is directly controlled. The present invention may be applied to such a system to determine whether or not there is an abnormality in the change characteristic of the actual supercharging pressure with respect to a change in the control signal input to the WGV.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a block diagram for demonstrating torque demand control and supercharging pressure control. It is a change characteristic figure of the actual supercharging pressure with respect to the change of TCV control duty value. It is a flowchart which shows the flow of a process of a regular determination routine. It is a flowchart which shows the flow of a process of WGV forced opening / closing mode determination routine. It is a flowchart which shows the flow of a process of abnormality diagnosis implementation flag operation routine. It is a flowchart which shows the flow of a process of a supercharging pressure control system abnormality diagnosis routine. It is a flowchart which shows the flow of a process of the supercharging pressure control system abnormality diagnosis routine in the modification of a present Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter, 16 ... Throttle valve, 17 ... Throttle opening sensor, 19 ... Intake pressure sensor, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust Pipe, 28 ... supercharger, 29 ... exhaust turbine, 30 ... compressor, 32 ... supercharging pressure sensor, 35 ... exhaust bypass passage, 36 ... WGV, 37 ... TCV, 40 ... crank angle sensor, 41 ... ECU (abnormality diagnosis) Means, torque demand control means, torque correction means)

Claims (6)

A supercharger that drives a compressor by an exhaust turbine provided in an exhaust passage of an internal combustion engine to supercharge intake air, and a waste gate valve (hereinafter referred to as “WGV”) that opens and closes an exhaust bypass passage that bypasses the exhaust turbine. A supercharging pressure control system that controls the actual supercharging pressure of the intake air supercharged by the supercharger by controlling the opening of the WGV.
The WGV control signal for controlling the opening degree of the WGV is forcibly changed when the internal combustion engine is in a steady operation state, and the actual excess with respect to the change of the WGV control signal is based on the actual boost pressure at that time. An abnormality diagnosing device for a supercharging pressure control system, comprising an abnormality diagnosing means for determining whether there is an abnormality in a change characteristic of the supply pressure.   2. The abnormality diagnosis device for a supercharging pressure control system according to claim 1, further comprising torque demand control means for calculating a control parameter of the internal combustion engine so as to realize a required torque of the internal combustion engine.   2. The torque correction means for correcting a control parameter of the internal combustion engine so as to suppress a torque fluctuation when the WGV control signal is forcibly changed by the abnormality diagnosis means. Abnormality diagnosis device for supercharging pressure control system.   The abnormality diagnosis means performs an abnormality diagnosis of the change characteristic of the actual supercharging pressure by forcibly changing the WGV control signal when the internal combustion engine is in a steady operation state in a medium load / medium rotational speed region. The abnormality diagnosis device for a supercharging pressure control system according to claim 2 or 3.   Each time the abnormality diagnosis means forcibly changes the WGV control signal by a predetermined amount, the abnormality diagnosis means responds to a change in the WGV control signal based on a deviation between a target boost pressure corresponding to the WGV control signal and an actual boost pressure. The abnormality diagnosis device for a supercharging pressure control system according to any one of claims 1 to 4, wherein presence / absence of abnormality of the change characteristic of the actual supercharging pressure is determined.   The abnormality diagnosing means changes the actual boost pressure change characteristic with respect to the change in the WGV control signal based on the change amount or change rate of the actual boost pressure every time the WGV control signal is forcibly changed by a predetermined amount. The abnormality diagnosis device for a supercharging pressure control system according to any one of claims 1 to 4, wherein presence or absence of abnormality is determined.

Images