JP5287673B2 - Abnormal site diagnosis device - Google Patents

Description

  The present invention relates to an abnormal part diagnostic apparatus for diagnosing so that an abnormal part of a feedback control system of an internal combustion engine can be specified.

  A general internal combustion engine includes a fuel injection valve that injects fuel to be used for combustion, a pump device that supplies pressurized fuel to the fuel injection valve, and a fuel pressure sensor that detects the pressure of the supplied fuel. The operation of the pump device is feedback-controlled so that the actual fuel pressure detected by the fuel pressure sensor becomes the target fuel pressure. Alternatively, when a pressure reduction control valve for controlling the pressure of the supplied fuel is provided, the operation of the pressure reduction control valve is feedback controlled so that the actual fuel pressure becomes the target fuel pressure (see Patent Document 1).

  When any abnormality occurs in a fuel injection system (feedback control system) including a fuel injection valve, a pump device, a fuel pressure sensor, a pressure reduction control valve, etc., the actual fuel pressure becomes abnormally lower than the target fuel pressure. The responsiveness of the actual fuel pressure to the target fuel pressure becomes worse, for example, the responsiveness of the actual fuel pressure to the target fuel pressure becomes worse. Therefore, conventionally, an abnormality in the fuel injection system has been detected based on the deviation between the target fuel pressure and the actual fuel pressure.

JP-T-2002-538368

  However, although the above-described abnormality detection method can detect an abnormality (system abnormality) of the fuel injection system, it cannot determine even the abnormal part. Therefore, even if a system abnormality is detected due to an abnormality in the fuel pressure sensor, repair work is inefficient, such as a repair worker replacing the entire fuel injection system including the pump device. It is the actual situation.

  The above problem is not limited to the feedback control of the operation of the pump device and the pressure reduction control valve using the detection value (actual fuel pressure) of the fuel pressure sensor, and various problems are detected using the detection values of various sensors mounted on the internal combustion engine. The same can occur when the actuator operation is feedback controlled.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an abnormal part diagnosis apparatus that performs diagnosis so that an abnormal part of a feedback control system can be identified.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

In the first invention, an actuator that controls the operating state of the internal combustion engine, a sensor that detects a physical quantity that changes in accordance with the operation of the actuator, and a detection value of the sensor that is a target value or an expected value for control. Feedback control means for feedback-controlling the operation of the actuator, and when the following value of the detected value with respect to the target value or the expected value is abnormal, the feedback control system A system abnormality determining means for determining that a system abnormality has occurred, and an open control means for stopping the feedback control to open control the operation of the actuator when it is determined that the system abnormality has occurred; Operating conditions of the internal combustion engine when the open control is performed The basis, characterized in that it comprises, and abnormalities specifying means for specifying a site that cause the system abnormality of the feedback control system.

  Here, if the feedback control is switched to the open control when a system abnormality occurs, there will be a considerable change in the operating state of the internal combustion engine. Depending on whether it is, it becomes a change of a different aspect.

  According to the above-described invention made by paying attention to this point, when it is determined that a system abnormality has occurred in the feedback control system, the feedback control is stopped and the open control is performed, and the internal combustion at the time of the open control is performed. Since the site causing the system abnormality is specified based on the operating state of the engine, not only the system abnormality is detected but also the abnormal site can be diagnosed.

In the second invention, the abnormal part specifying means diagnoses that the abnormal part is the sensor if the internal combustion engine can maintain a minimum operating state when the open control is performed. It is characterized by that.

  If the open control is performed when the system is abnormal, the operation state of the internal combustion engine is unlikely to deviate significantly from the desired state if other parts such as the actuator are normal even if the sensor is abnormal. On the other hand, if a part other than the sensor (for example, an actuator) is abnormal, the operation state of the internal combustion engine is highly likely to deviate from a desired state. According to the above invention in view of this point, as a result of performing the open control when the system is abnormal, if the internal combustion engine can maintain the minimum operating state, the abnormal part is diagnosed as a sensor. Can be realized with high accuracy.

In a third aspect of the invention, the actuator is a pump device that supplies boosted fuel to a fuel injection valve, and the sensor is a fuel pressure sensor that detects the pressure of fuel supplied to the fuel injection valve. And

  Abnormal parts other than the sensor in this case include a pump device, a fuel injection valve, a fuel pipe connected to the pump device or the fuel injection valve, and a pressure accumulation distribution container (delivery pipe) that distributes the accumulated fuel to a plurality of fuel injection valves. Etc. When such a fuel supply system is applied as a feedback control system as a diagnosis target, the internal combustion engine operating state at the time of open control when the sensor is abnormal and the other parts are abnormal The difference appears significantly in the driving state.

  For example, if a part other than the sensor (for example, the pump device) is abnormal, there is a high possibility that the actual fuel pressure supplied to the fuel injection valve is significantly lower than the target fuel pressure. Therefore, if open control is performed under such circumstances, the actual fuel pressure is regarded as the target fuel pressure and the fuel injection valve is operated to cause a shortage of injection amount, resulting in a significant increase in the output torque (operating state) of the internal combustion engine. There is a high possibility that it will decrease, and in some cases, misfire of the internal combustion engine will be caused. On the other hand, if the pump device is normal, the fuel pressure supplied to the fuel injection valve will not drop significantly even if the fuel pressure sensor is abnormal. Torque does not decrease significantly and the possibility of misfire is very low.

  Therefore, according to the above-described invention in which the fuel supply system is to be diagnosed, it is possible to suitably realize the identification of the part that is causing the system abnormality based on the operating state of the internal combustion engine during the open control.

In a fourth aspect of the invention, the pump device includes a high-pressure pump that raises the pressure of fuel to the target value or the expected value, and a low-pressure pump that supplies fuel to the high-pressure pump. It is determined that the system is abnormal, comprising low-pressure fail-safe control means for performing low-pressure fail-safe control of the pump device so that fuel is supplied to the fuel injection valve by the low-pressure pump in a state where pressure increase by the pump is stopped, And when it is not diagnosed that the abnormal part is the fuel pressure sensor, the low-pressure fail-safe control is performed by terminating the implementation of the open control.

  Here, when it is determined that the system is abnormal and it is not diagnosed that the abnormal part is the fuel pressure sensor, there is a concern about misfire of the internal combustion engine due to the insufficient injection amount described above, but the pressure is excessively increased. It is feared that the fuel is supplied from the pump device and the fuel pipe, the pressure distribution container (delivery pipe), and the fuel injection valve are damaged.

  According to the above invention in view of this point, in the case of a system abnormality due to an abnormality other than the fuel pressure sensor, the implementation of the open control is terminated and switched to the feedback control, thereby eliminating the fear of misfire due to insufficient injection amount by the open control. it can. Moreover, since the low-pressure fail-safe control is performed so that fuel is supplied from the low-pressure pump while the pressure increase by the high-pressure pump is stopped, the low-pressure pump is driven while the fear of damage due to excessive pressure increase is eliminated by stopping the high-pressure pump. Thus, the fuel supply to the fuel injection valve can be maintained. In addition, although the pressure of the fuel to be supplied is low in the low-pressure fail-safe control, since the valve opening time of the fuel injection valve is set long by the feedback control, the fear of misfire due to insufficient injection amount is solved. .

According to a fifth aspect of the invention, when it is determined that the system is abnormal and the abnormal part is diagnosed as the sensor, the open control is continued as fail-safe control.

Here, even if the system is abnormal, if a part other than the sensor (such as an actuator) is normal, breakage or injection due to excessive pressure increase without performing the low-pressure failsafe control of the fourth invention described above. The possibility of misfire due to lack of quantity is low. According to the above-mentioned invention in view of this point, since open control is continued as fail-safe control at the time of system abnormality caused by sensor abnormality, compared with the case where low-pressure fail-safe control is performed without causing the above-described damage and misfire. The actual fuel pressure can be brought close to the target fuel pressure. Further, the concern about the deterioration of controllability due to the feedback control using an abnormal sensor can be solved by continuing the open control.

  In short, in the above-described invention, when the sensor is abnormal, excessive fail-safe such as low-pressure fail-safe control is not performed, and open control is performed instead of feedback control using an abnormal sensor.

In a sixth aspect of the present invention, the implementation of the open control is forcibly terminated when the implementation duration time of the open control reaches a predetermined time limit.

  If the above open control is continued for a long time, the feedback control system may be damaged. For example, in the case of the fuel supply system described above, the fuel in a portion (for example, a pressure accumulating distribution container, a fuel pipe, or a fuel injection valve) located on the downstream side of the pump device becomes high temperature, and as a result, the fuel is abnormally boosted. This may cause damage to the part.

  On the other hand, according to the above invention, since the execution of the open control is forcibly terminated when the execution duration time of the open control reaches a predetermined time limit, the fear of damage can be solved.

1 is a diagram illustrating an overall configuration of a fuel supply system to which an abnormal region diagnosis apparatus according to a first embodiment of the present invention is applied. The flowchart which shows the process sequence which feedback-controls the action | operation of a high pressure pump in 1st Embodiment. The flowchart which shows the process sequence of fuel injection amount control in 1st Embodiment. The flowchart which shows the process sequence of the abnormality determination process and abnormal part diagnosis process of a fuel supply system in 1st Embodiment. The flowchart which shows the process sequence of the abnormality determination process of a fuel supply system, and an abnormal region diagnosis process in 2nd Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment in which an abnormal region diagnosis apparatus according to the present invention is applied to a fuel supply system for an internal combustion engine will be described with reference to the drawings.

  First, a schematic configuration of the entire fuel supply system of an in-cylinder injection engine (internal combustion engine) will be described with reference to FIG. In addition, although the ignition type gasoline engine is assumed in the engine of FIG. 1, this invention is applicable also to a self-ignition type diesel engine.

  A low pressure pump 12 that pumps up the fuel is installed in the fuel tank 11 that stores the fuel. The low-pressure pump 12 is driven by an electric motor (not shown) that uses a battery (not shown) as a power source. The fuel discharged from the low pressure pump 12 is supplied to the high pressure pump 14 through the low pressure fuel pipe 13.

  The high-pressure pump 14 is a piston pump that reciprocates a piston 19 in a cylindrical pump chamber 18 and sucks / discharges fuel. The piston 19 rotates by a cam 21 fitted to a camshaft 20 of the engine. Driven by. A fuel pressure control valve 23 is provided on the suction port 22 side of the high-pressure pump 14. The fuel pressure control valve 23 is a normally open type electromagnetic valve, and includes a valve body 24 that opens and closes the suction port 22, a spring 25 that urges the valve body 24 in the valve opening direction, and a valve body 24 in the valve closing direction. And a solenoid 26 that is electromagnetically driven.

  During the suction stroke of the high-pressure pump 14 (when the piston 19 is lowered), the fuel pressure control valve 23 is opened and fuel is sucked into the pump chamber 18, and during the discharge stroke of the high-pressure pump 14 (when the piston 19 is raised). By controlling the valve closing time of the fuel pressure control valve 23 (the valve closing time from the valve closing start time to the top dead center of the piston 19), the discharge amount of the high-pressure pump 14 is controlled to control the fuel pressure (discharge pressure). To control.

  That is, when increasing the fuel pressure, the valve closing start timing (energization timing) of the fuel pressure control valve 23 is advanced, thereby extending the valve closing time of the fuel pressure control valve 23 and increasing the discharge amount of the high pressure pump 14. Conversely, when lowering the fuel pressure, the valve closing start timing (energization timing) of the fuel pressure control valve 23 is retarded, thereby shortening the valve closing time of the fuel pressure control valve 23 and reducing the discharge amount of the high pressure pump 14. .

  On the other hand, a check valve 28 for preventing the backflow of discharged fuel is provided on the discharge port 27 side of the high-pressure pump 14. The fuel discharged from the high-pressure pump 14 is sent to a delivery pipe 30 (pressure accumulation container) through a high-pressure fuel pipe 29 (high-pressure fuel passage), and a fuel injection valve attached to the upper part of each cylinder of the engine from the delivery pipe 30. The high-pressure fuel is distributed to 31. The delivery pipe 30 is provided with a fuel pressure sensor 32 that detects the fuel pressure (fuel pressure) in the delivery pipe 30.

  The low-pressure pump 12, the low-pressure fuel pipe 13, and the high-pressure pump 14 described above correspond to the components of the “pump device”. The pump device, the fuel pressure sensor 32, the check valve 28, the high-pressure fuel pipe 29, the delivery pipe 30, and the fuel injection valve 31 correspond to the components of the “fuel supply system”.

  Further, the engine is provided with an air flow meter 36 for detecting the intake air amount V and a crank angle sensor 37 for outputting a crank angle signal pulse at every predetermined crank angle in synchronization with rotation of a crankshaft (not shown). It has been. Based on the output signal of the crank angle sensor 37, the crank angle and the engine speed NE are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU 38”). The ECU 38 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel of the fuel injection valve 31 depends on the engine operating state. The injection amount and the ignition timing of a spark plug (not shown) are controlled. At that time, the ECU 38 feedback controls the discharge amount of the high-pressure pump 14 (the closing time of the fuel pressure control valve 23) so that the fuel pressure in the delivery pipe 30 detected by the fuel pressure sensor 32 matches the target fuel pressure.

  FIG. 2 is a flowchart showing the processing procedure of the feedback control by the microcomputer of the ECU 38, and the process is repeatedly executed at a predetermined cycle (for example, every calculation cycle performed by the CPU of the microcomputer or every predetermined crank angle).

  First, in step S10 shown in FIG. 2, the engine rotational speed NE detected by the crank angle sensor 37 and the intake air amount V (engine load) detected by the air flow meter 36 are acquired, and based on these NE and V. Set the target fuel pressure. Specifically, the optimal fuel pressure for NE and V is tested in advance to create a map, and the target fuel pressure is calculated based on the map and the acquired NE and V.

  In subsequent step S11, the actual fuel pressure detected by the fuel pressure sensor 32 is acquired, and the deviation between the target fuel pressure set in step S10 and the actual fuel pressure is calculated. In the subsequent step S12 (feedback control means), the valve closing time of the fuel pressure control valve 23 of the high pressure pump 14 is feedback controlled based on the deviation calculated in step S11. Specifically, if the actual fuel pressure is higher than the target fuel pressure, the actual fuel pressure is increased by advancing the valve closing start timing (energization timing) of the fuel pressure control valve 23 by an amount corresponding to the deviation. On the other hand, if the actual fuel pressure is lower than the target fuel pressure, the actual fuel pressure is lowered by retarding the valve closing start timing of the fuel pressure control valve 23 by an amount corresponding to the deviation.

  FIG. 3 is a flowchart showing a processing procedure of fuel injection amount control by the microcomputer of the ECU 38, and this process is repeatedly executed at a predetermined cycle (for example, every calculation cycle performed by the microcomputer CPU or every predetermined crank angle).

  First, in step S20 shown in FIG. 3, the engine rotational speed NE detected by the crank angle sensor 37 and the intake air amount V (engine load) detected by the air flow meter 36 are acquired, and based on these NE and V. Then, a target injection amount of fuel to be injected from the fuel injection valve 31 is set. Specifically, the optimal injection amount for NE and V is tested in advance to create a map, and the target injection amount is calculated based on the map and the acquired NE and V.

  In the subsequent step S21, the valve opening command time of the fuel injection valve 31 is calculated based on the target injection amount calculated in step S20 and the actual fuel pressure detected by the fuel pressure sensor 32. That is, the fuel injection amount increases as the valve opening time of the fuel injection valve 31 increases, and the fuel injection amount increases as the actual fuel pressure increases even at the same valve opening time. Therefore, the valve opening command time is calculated based on the actual fuel pressure in addition to the target injection amount.

  Next, an abnormality determination process for the fuel supply system, which is a main part of the present embodiment, and a diagnosis process for identifying an abnormal part will be described below.

  FIG. 4 is a flowchart showing a processing procedure of the abnormality determination and abnormal part diagnosis by the microcomputer of the ECU 38, and the processing is repeatedly executed at a predetermined cycle (for example, every calculation cycle performed by the CPU of the microcomputer or every predetermined crank angle). The

  First, in step S30 (system abnormality determination means) shown in FIG. 4, whether or not an abnormality is observed in the followability of the actual fuel pressure (detected value) with respect to the target fuel pressure (target value) when performing the feedback control of FIG. Determine. If an abnormality is observed in the followability, it is determined that the abnormality is occurring in any of a plurality of parts constituting the fuel supply system if an abnormality is observed in the followability. In this embodiment, when it is determined that the system is abnormal, it is considered that there is a high possibility that an abnormality has occurred in either the high-pressure pump 14 or the fuel pressure sensor 32.

  Specifically, it is determined that there is a follow-up abnormality when a state where the deviation between the target fuel pressure and the actual fuel pressure is a predetermined amount or more continues for a predetermined time or more. For example, if an abnormality has occurred in the high-pressure pump 14 and sufficient pressure increase cannot be performed, the actual fuel pressure is significantly lower than the target fuel pressure, so that it is determined that the system is abnormal. Further, for example, when the fuel pressure sensor 32 deteriorates over time and the detection accuracy of the fuel pressure deteriorates, the followability of the actual fuel pressure with respect to the change in the target fuel pressure is deteriorated, so that it is determined that the system is abnormal.

  The fuel supply system is provided with a circuit (not shown) that detects disconnection and short circuit of the fuel pressure sensor 32. In addition to the system abnormality determination in step S30, the disconnection and short circuit detection is performed. The diagnosis process of FIG. 4 is executed on condition that a disconnection or a short circuit is not detected.

  If it is not determined in step S30 that the system is abnormal (S30: NO), the process in FIG. 4 is terminated. If it is determined that a system abnormality has occurred (S30: YES), the processes in subsequent steps S31 to S38 are performed. This diagnoses which part of the fuel supply system is abnormal.

  That is, first, in step S31 (open control means), the feedback control of the high-pressure pump 14 performed in step S12 of FIG. 2 is stopped, and the high-pressure pump 14 is open-controlled. For example, the actual fuel pressure is regarded as the target fuel pressure (the deviation in step S11 is regarded as zero), and the valve closing time of the fuel pressure control valve 23 may be controlled open (determination fail-safe control FS1). Further, with this open control, the actual fuel pressure is regarded as the target fuel pressure, and the valve opening command time is calculated in step S21 of FIG.

  In a succeeding step S32, it is determined whether or not the continuous duration of the open control in the step S31 has reached a predetermined time limit TH. If it is determined that the time limit TH has been reached (S32: NO), the open control is forcibly terminated in the subsequent step S33, and the process of FIG. 4 is terminated.

  On the other hand, if it is determined that the time limit TH has not been reached (S32: YES), whether or not the engine can no longer maintain the minimum operating state with the execution of the open control in the subsequent step S34 (abnormal part specifying means). Determine whether. For example, it may be determined whether the engine can no longer be started, it may be determined whether the engine speed NE is below a predetermined lower limit value, or the excess air ratio λ exceeds a predetermined range. It may be determined whether or not.

  Here, when it is determined that the system is abnormal because the fuel pressure sensor 32 is abnormal (S30: YES), when the high-pressure pump 14 is controlled to open, it is compared to the case where feedback control is performed at normal time. Since the actual fuel pressure cannot be brought close to the target fuel pressure, the actual injection amount deviates from the target injection amount of fuel. However, since the high-pressure pump 14 is normal, the actual fuel pressure does not deviate significantly from the target fuel pressure, and thus the actual injection amount does not deviate significantly from the target injection amount. Therefore, when the fuel pressure sensor 32 is abnormal and the high-pressure pump 14 is normal, the output torque and the exhaust emission are not significantly impaired even if the open control is performed. Specifically, the engine speed NE can be maintained at a predetermined value or higher, and no misfire occurs. Further, the excess air ratio λ can be maintained within a predetermined range.

  On the other hand, when it is determined that the system is abnormal (S30: YES) due to a pressure increase abnormality in which the high pressure pump 14 cannot normally increase the pressure, the actual fuel pressure supplied to the fuel injection valve 31 is less than the target fuel pressure. It drops significantly. Since the actual fuel pressure is assumed to be the target fuel pressure for performing the open control of the high-pressure pump 14, the valve opening command time is calculated in step S21 in FIG. It will be significantly less than the quantity. Therefore, when the high pressure pump 14 is abnormal and the fuel pressure sensor 32 is normal, the fuel injection amount becomes insufficient when the open control is performed, and the output torque and the exhaust emission are greatly impaired. Specifically, the engine cannot be started due to a misfire, and the excess air ratio λ exceeds a predetermined range to be in a lean state. For example, the exhaust cannot be properly purified by a purification device such as a three-way catalyst.

  In view of the above points, when it is determined in step S34 that the engine can be started (S34: YES), in the subsequent step S35 (abnormal part specifying means), the part causing the system abnormality is the fuel pressure sensor 32. Diagnose that. In this case, as described above, the engine output torque and the exhaust emission are not greatly impaired. In the subsequent step S36, the open control in step S32 is continued as fail-safe control.

  On the other hand, when it is determined that the engine cannot be started (S34: NO), in the subsequent step S37 (abnormal part specifying means), the part causing the system abnormality is diagnosed as the high-pressure pump 14 (actuator). . In this case, in order to start the engine, in the subsequent step S38 (low pressure fail safe control means), the open control in step S32 is terminated, and the operation of the pump device is controlled by the low pressure fail safe control FS2 described below. To do.

  That is, in the low pressure fail safe control FS2, the pressure increasing operation by the high pressure pump 14 is stopped, and the fuel is supplied to the delivery pipe 30 by the low pressure pump 12. Specifically, energization of the solenoid 26 is prohibited, and the valve body 24 is always opened. As a result, the fuel pressurized by the low pressure pump 12 is supplied to the delivery pipe 30 from the discharge port 27 through the pump chamber 18 while maintaining the low pressure. In the low pressure fail safe control FS2, the valve opening command time is calculated based on the actual fuel pressure in step S21 of FIG. As a result, the valve opening command time is set to be long as the supplied fuel is at a low pressure, so that it is possible to avoid a shortage of injection amount that may cause misfire, and the engine can be degenerated. Become.

  Incidentally, in the determination in step S34, an affirmative determination is made on the condition that the excess air ratio λ is within a predetermined range in addition to the condition that the engine can be started, and diagnosis that the fuel pressure sensor 32 is abnormal (S35). You may make it do.

  As described above, according to the present embodiment, the following effects can be obtained.

  (1) When a system abnormality is detected (S30: YES), the determination fail-safe control FS1 in which the engine operating state changes according to the abnormal part is performed, so that a diagnosis for specifying the abnormal part is possible. That is, the determination fail-safe control FS1 considers the actual fuel pressure to be the target fuel pressure, performs open control of the high-pressure pump 14 and calculates the valve opening command time. As a result, if the engine fails to start as a result of the determination fail-safe control FS1, it can be diagnosed that the part causing the system abnormality is the high-pressure pump 14, and if the engine can be started, the part causing the system abnormality is The fuel pressure sensor 32 can be diagnosed.

  (2) If it is diagnosed that the cause of the system abnormality is the high-pressure pump 14, the engine cannot be started. In this case, the determination fail-safe control FS1 (open control) is immediately stopped. The control is switched to the low-pressure fail-safe control FS2 for feedback control. Therefore, it is possible to quickly return to a state where the engine can be started. Moreover, in the low pressure fail safe control FS2, the fuel supply to the fuel injection valve 31 is performed by supplying the fuel with the low pressure pump 12 while eliminating the fear of the damage due to the excessive pressure increase by stopping the pressurization by the high pressure pump 14. Can be maintained.

  (3) Since the engine can be started if the pump device is normal even if the system is abnormal, the low-pressure fail-safe control is excessively safe and unnecessary. In this embodiment in view of this point, when it is diagnosed that the cause of the system abnormality is the fuel pressure sensor 32, the determination fail-safe control FS1 is continued, so that compared with the case where the low-pressure fail-safe control is performed. The actual fuel pressure can be sufficiently increased, so that the shortage of the fuel injection amount can be suppressed. Further, the concern about the deterioration of controllability due to the feedback control using the abnormal fuel pressure sensor 32 can be solved by continuing the open control.

  (4) Here, when the determination fail-safe control FS1 (open control) is continuously performed for a long time, the fuel in the delivery pipe 30 becomes high temperature, and as a result, the fuel pressure in the delivery pipe 30 becomes abnormally high. There is a concern that the delivery pipe 30 may be damaged. On the other hand, according to the present embodiment, the execution of the open control is forcibly terminated when the execution duration time of the open control reaches the predetermined limit time TH, so that the fear of damage can be solved.

(Second Embodiment)
In the first embodiment, it is diagnosed whether the cause of the system abnormality is the fuel pressure sensor 32 or the high-pressure pump 14, whereas in the present embodiment shown in FIG. 5, the fuel pressure sensor 32 and the low-pressure pump 12 are diagnosed. It is diagnosed whether it is either. Hereinafter, the difference between the processing contents of FIG. 5 and FIG. 4 will be described. In FIG. 5, the description of the same reference numerals as those in FIG. The hardware configuration of the fuel supply system in the present embodiment is the same as that in the first embodiment shown in FIG.

  Here, when the ignition switch is turned on (IG on), the low-pressure pump 12 using the electric motor as a drive source starts driving. Thereafter, when the crankshaft starts to rotate as the starter motor is started, the high-pressure pump 14 starts driving. That is, for a predetermined period after the IG is turned on, only the low-pressure pump 12 is driven while the high-pressure pump 14 is stopped. Therefore, during this predetermined period, the system abnormality determination similar to step S30 of FIG. 4 is performed, and as a result, when it is determined that the system is abnormal, either the low pressure pump 12 or the fuel pressure sensor 32 may be abnormal. Therefore, it can be diagnosed that the possibility that the high-pressure pump 14 is abnormal is low.

  In this embodiment in consideration of this point, first, in step S300 of FIG. 5, is there any abnormality in the followability of the actual fuel pressure with respect to the target fuel pressure when the feedback control of FIG. Determine whether or not. If an abnormality is found in the followability, it is determined that the system abnormality is occurring in any of a plurality of parts constituting the fuel supply system. When it is determined that the system is abnormal in the present embodiment, it is considered that there is a high possibility that an abnormality has occurred in either the low-pressure pump 12 or the fuel pressure sensor 32.

  Specifically, in the same manner as in step S30 of FIG. 4, for example, when the low pressure pump 12 is abnormal and the minimum pressure increase cannot be performed, the actual fuel pressure is significantly lower than the target fuel pressure. It is determined that the system is abnormal. Further, for example, when the fuel pressure sensor 32 deteriorates over time and the detection accuracy of the fuel pressure deteriorates, the followability of the actual fuel pressure with respect to the change in the target fuel pressure is deteriorated, so that it is determined that the system is abnormal. In the same manner as in FIG. 4, the diagnosis process in FIG. 5 is executed on condition that disconnection or short circuit of the fuel pressure sensor 32 is not detected.

  If it is not determined in step S300 that the system is abnormal (S300: NO), the process in FIG. 5 is terminated. If it is determined that a system abnormality has occurred (S300: YES), steps S31 to S38 in FIG. By performing similar processing, it is diagnosed in which part of the fuel supply system an abnormality has occurred.

  That is, in step S31, the actual fuel pressure is regarded as the target fuel pressure in accordance with the open control, and the valve opening command time is calculated in step S21 of FIG. If it is determined that the execution duration time of the open control has reached the limit time TH (S32: NO), the open control is forcibly terminated in the subsequent step S33, and the process of FIG. 5 is terminated.

  On the other hand, if it is determined that the time limit TH has not been reached (S32: YES), in the subsequent step S34, it is determined whether or not the engine can no longer maintain the minimum operating state due to the implementation of the open control. For example, it may be determined whether or not the engine can no longer be started, or it may be determined whether or not the engine speed NE is below a predetermined lower limit value. However, when it is determined that the engine cannot be started (S34: NO), in the first embodiment, the high pressure pump 14 is diagnosed as abnormal in step S37, whereas in this embodiment, the low pressure is determined in step S370. Diagnose that the pump 12 (actuator) is abnormal.

  As described above, according to the present embodiment, the same effects as the effects (3) and (4) according to the first embodiment can be obtained, and the following effects (1 ′) and (2) corresponding to the effects (1) and (2) can be obtained. 2 ′) is obtained.

  (1 ′) When the system abnormality is detected, it is assumed that the actual fuel pressure is the target fuel pressure, and the determination fail-safe control FS1 for calculating the valve opening command time is performed. Therefore, after the IG is turned on, the high-pressure pump 14 As a result of performing the fail-safe control FS1 for determination in a predetermined period until driving, if the engine cannot be started, it can be diagnosed that the site causing the system abnormality is the low-pressure pump 12, and if the engine can be started, the system It can be diagnosed that the abnormality cause site is the fuel pressure sensor 32.

  (2 ′) When the engine failure is diagnosed because the cause of the system abnormality is the low-pressure pump 12, the determination fail-safe control FS1 is immediately stopped and switched to the low-pressure fail-safe control FS2. Can be quickly returned to a state where it can be started. Moreover, in the low pressure fail safe control FS2, the fuel supply to the fuel injection valve 31 is performed by supplying the fuel with the low pressure pump 12 while eliminating the fear of the damage due to the excessive pressure increase by stopping the pressurization by the high pressure pump 14. Can be maintained.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  While the user is operating the engine, the ECU 38 mounted on the engine may perform the on-board diagnostic processing shown in FIGS. 4 and 5, or a repair operator such as a dealer may be able to The diagnostic processing shown in FIGS. 4 and 5 may be performed off-board using the diagnostic device provided in FIG.

  In each of the above embodiments, the diagnostic device of the present invention is applied to a control system that feedback-controls the pump device. However, the diagnosis target of the present invention is not limited to the feedback control system of the pump device (actuator). For example, a system that performs feedback control of the operation of the pressure reduction control valve (actuator) provided in the delivery pipe 30 based on a deviation between the actual fuel pressure and the target fuel pressure may be a diagnosis target, A system that performs feedback control of the actuator may be a diagnosis target.

  In the above embodiment, the operation of the high-pressure pump (actuator) is feedback controlled so that the detected value of the fuel pressure sensor 32 becomes the target fuel pressure (target value), but instead of the target fuel pressure set based on NE and V, Feedback control may be performed so that the detected value becomes an expected value in control.

  DESCRIPTION OF SYMBOLS 12 ... Low pressure pump (pump apparatus (actuator)) 14 ... High pressure pump (pump apparatus (actuator)) 32 ... Fuel pressure sensor (sensor), S12 ... Feedback control means, S30 ... System abnormality determination means, S31 ... Open control means , S34, S35, S37 ... abnormal part specifying means, S38 ... low pressure fail safe control means.

Claims (5)

An actuator that controls the operating state of the internal combustion engine, a sensor that detects a physical quantity that changes with the operation of the actuator, and feedback control of the operation of the actuator so that the detected value of the sensor becomes a target value or an expected value for control A feedback control means configured to be applied to a feedback control system,
System abnormality determination means for determining that a system abnormality has occurred in the feedback control system when the followability of the detection value with respect to the target value or the expected value is abnormal;
When it is determined that the system abnormality has occurred, an open control unit that stops the feedback control and performs open control of the operation of the actuator;
If the internal combustion engine when performing the open control can maintain a minimum operating state, it is diagnosed that the abnormal part causing the system abnormality in the feedback control system is the sensor. And, if the internal combustion engine when performing the open control is not able to maintain a minimum operating state, abnormal part specifying means for diagnosing that the abnormal part is the actuator ,
An abnormal site diagnosis apparatus comprising: The actuator is a pump device that supplies boosted fuel to a fuel injection valve,
The abnormal part diagnosis apparatus according to claim 1, wherein the sensor is a fuel pressure sensor that detects a pressure of fuel supplied to the fuel injection valve. The pump device includes a high-pressure pump that boosts the pressure of fuel to the target value or the expected value, and a low-pressure pump that supplies fuel to the high-pressure pump.
Low pressure fail safe control means for performing low pressure fail safe control of the pump device so as to supply fuel to the fuel injection valve by the low pressure pump in a state where the pressure increase by the high pressure pump is stopped,
If it is determined that the system is abnormal and the abnormal part is not diagnosed as the fuel pressure sensor, the open control is terminated and switched to the feedback control and the low-pressure fail-safe control is performed. The abnormal part diagnosis apparatus according to claim 2 , wherein the abnormality part diagnosis apparatus is implemented. Is determined to be the system abnormality, and, when the abnormal position is diagnosed with said sensor, claim 1-3, characterized in that to continue the open control as a fail-safe control The abnormal part diagnostic apparatus as described in one. The abnormal part diagnosis apparatus according to any one of claims 1 to 4 , wherein the execution of the open control is forcibly terminated when the continuous duration of the open control reaches a predetermined time limit.

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