JP2010209825A - Failure diagnostic device for engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To specify a broken portion causing supercharging failure when the supercharging failure occurs. <P>SOLUTION: An ECU 30 diagnoses whether or not the supercharging failure occurs in an engine 10 based on the actual boost pressure. The ECU 30 diagnoses that air is leaked between a supercharger 13 and the engine 10 when it diagnoses that the supercharging failure occurs and the actual intake air volume is larger than a normal intake volume, and diagnoses that the supercharger 13 fails when the actual intake air volume is smaller than the normal intake air volume. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to failure diagnosis of a supercharged engine.

  If supercharging failure occurs in an engine with a supercharger, the output of a gasoline engine whose fuel injection amount is determined according to the intake air amount is reduced. Further, in a diesel engine in which the fuel injection amount is determined according to the accelerator opening and the engine speed, the air-fuel ratio becomes rich due to the reduction of the intake air amount, and the exhaust temperature rises. For this reason, in an engine with a supercharger, it is necessary to perform a fault diagnosis and switch to control corresponding to a supercharging failure when a diagnosis that a supercharging failure has occurred is made.

  In this regard, Patent Document 1 models a turbocharger, and based on a deviation between a supercharging pressure (model calculation value) calculated using the model and an actual measurement value of the supercharging pressure, A method for fault diagnosis is proposed.

JP 2005-155384 A

  The supercharging failure is caused not only by the failure of the supercharger but also by air leakage from the intake passage. In order to perform the control for the supercharging failure more appropriately, it is necessary to identify the faulty part causing the supercharging failure.

  The present invention has been made in view of such a technical problem, and an object of the present invention is to be able to identify a failure site that causes a supercharging failure when a supercharging failure occurs.

  According to an aspect of the present invention, there is provided a failure diagnosis device for a supercharged engine, an actual intake air amount detecting means for detecting an actual intake air amount of the engine, and an actual boost pressure for detecting an actual boost pressure of the engine. Detection means, supercharging failure diagnosis means for diagnosing whether or not supercharging failure has occurred in the engine based on the actual boost pressure, and the intake air amount (hereinafter referred to as “normal intake air amount”) of the engine obtained during normal supercharging. ) On the basis of the operating state of the engine, and the supercharger when the supercharging failure is diagnosed and the actual intake amount is greater than the normal intake amount And a failure site diagnosis means for diagnosing that the turbocharger has failed when the actual intake air amount is smaller than the normal intake air amount. Prepared Failure diagnosis apparatus is provided, wherein the door.

  According to the said aspect, it is diagnosed whether the supercharging defect has arisen in the engine based on the actual boost pressure. If it is diagnosed that a supercharging failure has occurred, whether the supercharging failure is due to air leakage or a turbocharger failure is based on the relationship between the actual intake air amount and the normal intake air amount. Further diagnosis is made. That is, according to the above aspect, it is possible not only to diagnose whether a supercharging failure has occurred, but also to identify the failure site that is the cause.

1 is a schematic configuration diagram of a failure diagnosis apparatus according to a first embodiment of the present invention. It is the flowchart which showed the content of the failure diagnosis process which an electronic control unit (ECU) performs. It is a figure for demonstrating the effect of this invention. It is a figure for demonstrating the effect of this invention. It is another example of the flowchart which showed the content of the failure diagnosis process which ECU performs (2nd Embodiment).

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

-First embodiment-
FIG. 1 shows a schematic configuration of a failure diagnosis apparatus according to the first embodiment of the present invention. This failure diagnosis device performs failure diagnosis of the engine 10.

  The engine 10 is a diesel engine with a supercharger. An air cleaner 12, a compressor 13 c of a supercharger 13, and an intercooler 14 are disposed in the intake passage 11 of the engine 10. The air from which the dust has been removed by the air cleaner 12 is compressed by the compressor 13 c, cooled by the intercooler 14, and then supplied to the engine 10.

  Between the air cleaner 12 and the compressor 13c, an air flow meter 21 for detecting an intake air amount (hereinafter referred to as “actual intake air amount”) Qa of the engine 10 is attached. A boost pressure sensor 22 for detecting a boost pressure (hereinafter referred to as “actual boost pressure”) Pa is attached between the intercooler 14 and the engine 10. These sensors 21 and 22 are electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 30. The attachment position of the air flow meter 21 may be on the inlet side of the air cleaner 12, and the attachment position of the boost pressure sensor 22 may be between the compressor 13 c and the intercooler 14.

  The air supplied to the engine 10 is compressed by a piston (not shown). When fuel is injected into the compressed air from an injector (not shown), the fuel self-ignites and combustion occurs. Exhaust gas from the engine 10 is discharged into the atmosphere via a three-way catalyst, a DPF, and a silencer (not shown) by rotating a turbine 13t of a supercharger 13 disposed in the exhaust passage 15.

  The supercharger 13 has a nozzle vane (not shown) on the inlet side of the turbine 13t. The boost pressure can be controlled to an arbitrary pressure by adjusting the flow rate of the exhaust gas flowing toward the turbine vane by displacing the nozzle vane.

  An atmospheric pressure sensor 23 that detects atmospheric pressure is electrically connected to the ECU 30. The ECU 30 is electrically connected to an engine controller (not shown) that controls the engine 10. A signal indicating the operating state of the engine 10 (rotational speed Ne, fuel injection amount Qf, accelerator opening ACC, etc.) is input to the ECU 30 from the engine controller.

  The ECU 30 includes a CPU 31, a storage device 32 including a RAM / ROM, an input / output interface 33, and the like. The storage device 32 stores a program and a map for executing failure diagnosis processing described later. The various signals are input to the input / output interface 33. The CPU 31 reads and executes a program stored in the storage device 32, and performs diagnosis of supercharging failure and identification of a faulty part that causes supercharging failure by a failure diagnosis process described below.

  FIG. 2 is a flowchart showing the contents of the failure diagnosis process. This failure diagnosis process is executed in the ECU 30 every predetermined time (for example, 10 msec). Hereinafter, the contents of the failure diagnosis process will be described with reference to this.

  In S11, the ECU 30 calculates a normal boost pressure Pn that is a boost pressure at the time of normal supercharging. Specifically, the ECU 30 sets the target boost pressure Pt by searching for values corresponding to the engine rotational speed Ne and the fuel injection amount Qf from a target boost pressure map prepared in advance. The target boost pressure Pt is set to be high in the high load region and the low rotation partial region, and to be low in the no load region. The ECU 30 calculates the normal boost pressure Pn by limiting the target boost pressure Pt below the upper limit boost pressure determined according to the atmospheric pressure, and further performing a delay process corresponding to the boost rise delay. Note that the target boost pressure Pt may be used as it is as the normal boost pressure Pn in a simplified manner.

  In S12, the ECU 30 reads a value obtained by subjecting the detected value of the boost pressure sensor 22 to a smoothing process as the actual boost pressure Pa. This annealing process is for removing noise included in the detected value.

  In S13, the ECU 30 calculates a deviation (hereinafter referred to as “boost deviation”) ΔPd between the normal boost pressure Pn and the actual boost pressure Pa (ΔPd = Pn−Pa).

  In S14, the ECU 30 sets a boost deviation limit ΔPdth, which is a diagnostic threshold value for diagnosing supercharging failure. Specifically, the ECU 30 sets a boost deviation limit ΔPdth by searching values corresponding to the engine speed Ne and the accelerator opening ACC from a boost deviation limit map prepared in advance. The boost deviation limit ΔPdth is set to a larger value as the engine speed Ne becomes higher and as the accelerator opening ACC becomes larger.

  In S15, the ECU 30 compares the boost deviation ΔPd with the boost deviation limit ΔPdth. If it is determined that boost deviation ΔPd is larger than boost deviation limit ΔPdth, the process proceeds to S16, and if not, the process proceeds to S24.

  In S16, the ECU 30 increments the counter. This counter has an initial value of zero and is used to measure an elapsed time after the boost deviation ΔPd becomes larger than the boost deviation limit ΔPdth.

  In S17, the ECU 30 determines whether the counter is greater than a predetermined value. The predetermined value is set to 200, for example. Since the execution interval of the process shown in FIG. 2 is 10 msec, in S17, the ECU 30 determines whether or not the boost deviation ΔPd continues for 2 sec or longer and is larger than the boost deviation limit ΔPdth. If it is determined that the counter is greater than the predetermined value, the process proceeds to S18, and if not, the process ends.

  When the process proceeds to S18, since the state where the boost pressure of the engine 10 does not increase continues, in S18, the ECU 30 diagnoses that the supercharging failure of the engine 10 has occurred. Further, the ECU 30 performs a diagnosis for identifying the cause (failure part) of the supercharging failure after S19.

  In S19, the ECU 30 calculates a normal intake air amount Qn that is an intake air amount during normal supercharging. Specifically, the ECU 30 sets the target intake air amount Qt by searching for a value corresponding to the engine rotational speed Ne and the fuel injection amount Qf from a target intake air amount map prepared in advance. The target intake air amount Qt is set to increase as the engine speed Ne increases and as the fuel injection amount Qf increases. The ECU 30 calculates a normal intake air amount Qn by performing a delay process corresponding to a delay until the throttle opening is changed and the change in the intake air amount appears with respect to the target intake air amount Qt. The target intake air amount Qt may be used as it is as the normal intake air amount Qn in a simplified manner.

  In S20, the ECU 30 reads the actual intake air amount Qa.

  In S21, the ECU 30 determines whether the actual intake air amount Qa is larger than the normal intake air amount Qn. If the actual intake air amount Qa is larger than the normal intake air amount Qn, the process proceeds to S22, and if not, the process proceeds to S23.

  When air leakage occurs due to pipe disconnection, cracks, etc. between the supercharger 13 and the engine 10, the pressure loss on the downstream side of the air leaking portion decreases, so the actual intake air amount Qa is normal. It becomes larger than the intake amount Qn. On the other hand, when the supercharger 13 has failed due to blade loss, bearing seizure, or the like, the actual intake air amount Qa is smaller than the normal intake air amount Qn because the supercharger 13 does not function.

  Therefore, in S22, the ECU 30 diagnoses that the supercharging failure is due to air leakage, and in S23, the ECU 30 diagnoses that the supercharging failure is due to the failure of the supercharger 13.

  On the other hand, when the process proceeds from S15 to S24, the ECU 30 makes a normal diagnosis that there is no supercharging failure in the engine 10.

  In S25, the ECU 30 resets the counter and ends the process.

  Then, the effect by performing the said process is demonstrated.

  According to the above process, it is diagnosed whether a supercharging failure has occurred in the engine 10 based on the actual boost pressure Pa (S11 to S18). When it is diagnosed that a supercharging failure has occurred, whether the supercharging failure is caused by air leakage or a failure of the turbocharger 13 is determined by the magnitude of the actual intake air amount Qa and the normal intake air amount Qn. Further diagnosis is made based on the relationship (S19 to S23). That is, according to the above process, it is possible not only to diagnose whether a supercharging failure has occurred, but also to identify the fault site that is the cause.

  The diagnosis result of the ECU 30 is transmitted to the engine controller. When the engine controller receives a diagnosis result that the supercharging failure has occurred, the engine controller performs control in consideration of the supercharging failure (for example, a calculation that takes into account a reduction in the intake air amount in fuel injection amount control or DPF regeneration processing, For example, the supercharger 13 is protected by reducing the exhaust flow rate to the vane.

  Further, according to the above processing, the supercharging failure is diagnosed based on the boost deviation ΔPd that is the deviation between the actual boost pressure Pa of the engine 10 and the normal boost pressure Pn (S11 to S18). When the supercharging failure occurs, the boost deviation ΔPd increases. According to this method, it is possible to accurately diagnose that the supercharging failure has occurred.

  Further, according to the above processing, the boost deviation limit ΔPdth used for the supercharging failure diagnosis is set to a larger value as the engine 10 becomes higher and the engine 10 becomes higher (S14). Since the boost deviation ΔPd at the time of poor supercharging changes according to the operating state of the engine 10, by making the boost deviation limit ΔPdth variable accordingly, the supercharging failure is diagnosed regardless of the operating state of the engine 10 can do.

  Further, according to the above processing, it is diagnosed that a supercharging failure has occurred when a state in which the boost deviation ΔPd is larger than the boost deviation limit ΔPdth continues for a predetermined time (S15 to S18). Thereby, the influence of noise can be eliminated and the diagnostic accuracy can be improved.

  FIG. 3 shows a state where diagnosis is performed when acceleration is started from 0 km / h in an air leak state, and FIG. 4 is a view when acceleration is started from 50 km / h in an air leak state. It shows how diagnosis is performed. In either case, even if the deviation ΔPd between the actual boost pressure Pa and the normal boost pressure Pn becomes larger than the boost deviation limit ΔPdth, the supercharging failure is not immediately diagnosed, and the supercharging failure is not made until this state continues for 2 seconds Is diagnosed.

  The above process can be performed regardless of whether the vehicle on which the engine 10 is mounted is accelerating or traveling in a steady manner, but is limited to accelerating when the difference between the actual boost pressure Pa and the normal boost pressure Pn is increased. If the above processing is performed, the diagnostic accuracy can be further improved.

  Further, in the above processing, the boost deviation limit ΔPdth is made variable according to the operating state of the engine 10, but this can be simplified and set to a fixed value.

-Second Embodiment-
Next, a second embodiment of the present invention will be described.

  The configuration of the failure diagnosis apparatus according to the second embodiment is the same as the configuration of the first embodiment shown in FIG. The second embodiment is different from the first embodiment in the content of the failure diagnosis process performed by the ECU 30, and will be described below focusing on the differences.

  FIG. 5 is a flowchart showing the contents of the failure diagnosis process. This failure diagnosis process is executed in the ECU 30 every predetermined time (for example, 10 msec).

  In S31, the ECU 30 determines whether the vehicle on which the engine 10 is mounted is accelerating. Whether or not the vehicle is accelerating can be determined based on the fuel injection amount of the engine 10, for example. If it is determined that the vehicle is accelerating, the process proceeds to S32. If not, the process ends.

  In S32, the ECU 30 reads the atmospheric pressure Po.

  In S33, the ECU 30 reads a value obtained by subjecting the detected value of the boost pressure sensor 22 to a smoothing process as the actual boost pressure Pa. This annealing process is for removing noise included in the detected value.

  In S34, the ECU 30 calculates a deviation (hereinafter referred to as “atmospheric pressure deviation”) ΔPo between the atmospheric pressure Po and the actual boost pressure Pa (ΔPo = Pa−Po).

  In S35, the ECU 30 sets an atmospheric pressure deviation limit ΔPoth that is a diagnosis threshold value for diagnosing supercharging failure. Specifically, the ECU 30 sets the atmospheric pressure deviation limit ΔPoth by searching values corresponding to the engine rotational speed Ne and the accelerator opening ACC from an atmospheric pressure deviation limit map prepared in advance. The atmospheric pressure deviation limit ΔPoth is set to a larger value as the engine speed Ne becomes higher and as the accelerator opening ACC becomes larger.

  In S36, the ECU 30 compares the atmospheric pressure deviation ΔPo with the atmospheric pressure deviation limit ΔPoth. If it is determined that the atmospheric pressure deviation ΔPo is smaller than the atmospheric pressure deviation limit ΔPoth, the process proceeds to S16, and if not, the process proceeds to S24.

  The processing after S16 and the processing after S24 are the same as the processing shown in FIG.

  Then, the effect by performing the said process is demonstrated.

  According to the above process, it is diagnosed whether a supercharging failure has occurred in the engine 10 based on the actual boost pressure Pa (S32 to S36, S16 to S18). When it is diagnosed that a supercharging failure has occurred, whether the supercharging failure is caused by air leakage or a failure of the turbocharger 13 is determined by the magnitude of the actual intake air amount Qa and the normal intake air amount Qn. Further diagnosis is made based on the relationship (S19 to S23). That is, according to the above process, it is possible not only to diagnose whether a supercharging failure has occurred, but also to identify the fault site that is the cause.

  Further, according to the above processing, the supercharging failure is diagnosed based on the atmospheric pressure deviation ΔPo that is the deviation between the atmospheric pressure Po and the actual boost pressure Pa (S32 to S36, S16 to S18). When a supercharging failure occurs, the pressure between the supercharger 13 and the engine 10 (= actual boost pressure Pa) is close to the atmospheric pressure Po as in the case of the naturally aspirated engine, and the atmospheric pressure deviation ΔPo becomes smaller. According to this method, it is possible to accurately diagnose that supercharging failure has occurred. However, since it is difficult to make a difference in the atmospheric pressure deviation ΔPo depending on whether the supercharging is normal or defective during steady running, the supercharging failure diagnosis by this method is performed only during acceleration (S31). By limiting the diagnosis to acceleration, the diagnosis accuracy can be ensured.

  Further, according to the above process, it is diagnosed that a supercharging failure has occurred when the atmospheric pressure deviation ΔPo is smaller than the atmospheric pressure deviation limit ΔPoth for a predetermined time (S36, S16 to S18). Thereby, the influence of noise can be eliminated and the diagnostic accuracy can be improved.

  In the above process, the atmospheric pressure deviation limit ΔPoth is made variable according to the operating state of the engine 10, but this can be simplified to a fixed value.

  The embodiment of the present invention has been described above, but the above embodiment is merely an example of application of the present invention, and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment.

  For example, in the above embodiment, the engine 10 is a turbocharged diesel engine, but the failure diagnosis device according to the present invention can also be used for failure diagnosis of a turbocharged gasoline engine.

DESCRIPTION OF SYMBOLS 10 ... Engine 11 ... Intake passage 13 ... Supercharger 15 ... Exhaust passage 21 ... Air flow meter (actual intake air amount detection means)
22 ... Boost pressure sensor (actual boost pressure detection means)
23 ... Atmospheric pressure sensor (atmospheric pressure detecting means)
30 ... Electronic control unit (ECU)
S19: Normal intake air amount calculation means S11-S18, S32-S36 ... Supercharging failure diagnosis means S19-S23 ... Failure part diagnosis means S31 ... Acceleration determination means

Claims (7)

A failure diagnosis device for a turbocharged engine,
An actual intake air amount detecting means for detecting an actual intake air amount of the engine;
An actual boost pressure detecting means for detecting an actual boost pressure of the engine;
Supercharging failure diagnosis means for diagnosing whether supercharging failure has occurred in the engine based on the actual boost pressure;
Normal intake air amount calculating means for calculating the intake air amount of the engine (hereinafter referred to as “normal intake air amount”) obtained during normal supercharging, based on the operating state of the engine;
When the supercharging failure is diagnosed, and when the actual intake amount is larger than the normal intake amount, it is diagnosed that an air leak has occurred between the supercharger and the engine, When the actual intake air amount is smaller than the normal intake air amount, a failure part diagnosis means for diagnosing that the turbocharger has failed,
A failure diagnosis apparatus comprising: The failure diagnosis device according to claim 1,
A normal boost pressure calculating means for calculating a boost pressure obtained during normal supercharging (hereinafter referred to as “normal boost pressure”) based on the operating state of the engine;
The supercharging failure diagnosis means diagnoses that the supercharging failure has occurred when a deviation between the actual boost pressure and the normal boost pressure is larger than a diagnosis threshold value.
A fault diagnosis apparatus characterized by that. The failure diagnosis apparatus according to claim 2,
The supercharging failure diagnosis means sets the diagnosis threshold to a larger value as the engine becomes higher in rotation and as the engine becomes higher in load.
A fault diagnosis apparatus characterized by that. The failure diagnosis apparatus according to claim 2 or 3,
The supercharging failure diagnosis means diagnoses that the supercharging failure has occurred when a state where a deviation between the actual boost pressure and the normal boost pressure is larger than the diagnosis threshold value continues for a predetermined time period.
A fault diagnosis apparatus characterized by that. The fault diagnosis apparatus according to any one of claims 2 to 4,
Accelerating determination means for determining whether the vehicle equipped with the engine is accelerating,
The supercharging failure diagnosis means diagnoses the supercharging failure only when it is determined that the vehicle is accelerating.
A fault diagnosis apparatus characterized by that. The failure diagnosis device according to claim 1,
Acceleration determination means for determining whether the vehicle on which the engine is mounted is accelerating;
Atmospheric pressure detection means for detecting atmospheric pressure;
With
The supercharging failure diagnosis means determines that the supercharging failure has occurred when it is determined that the vehicle is accelerating and a deviation between the actual boost pressure and the atmospheric pressure is smaller than a diagnostic threshold value. To diagnose,
A fault diagnosis apparatus characterized by that. The fault diagnosis apparatus according to claim 6,
The supercharging failure diagnosis means determines that the vehicle is accelerating, and the state where the deviation between the actual boost pressure and the atmospheric pressure is smaller than the diagnosis threshold value continues for a predetermined time. Diagnosing supercharging failure,
A fault diagnosis apparatus characterized by that.

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