JP4407608B2 - Abnormality judgment device for pressure accumulating injector - Google Patents

Description

  The present invention relates to an abnormality determination device for an accumulator injection device.

  As a diesel engine fuel injection system, a high-pressure fuel equivalent to the fuel injection pressure is stored in a common rail, and the high-pressure fuel stored in the common rail is injected into the engine via a fuel injection valve. The system has been put into practical use. In this accumulator fuel injection system, when fuel injection is performed by the fuel injection valve, the fuel pressure in the common rail decreases. At this time, the high pressure fuel is discharged from the fuel supply pump to the common rail, and the common rail is thereby discharged. It is held at a predetermined high pressure state.

  For example, an electromagnetically driven fuel metering valve is provided in the fuel intake portion of the fuel supply pump, and the fuel discharge amount by the fuel supply pump is controlled by operating the opening of the fuel metering valve, The common rail pressure is controlled to a desired pressure. The fuel metering valve has a valve body for controlling the opening area (flow path area) of the fuel path. When the valve body is displaced in a sliding state in the valve case, the opening area of the fuel path is reduced. Be controlled. At this time, the valve body is displaced according to the command current value for the solenoid coil.

  In the system described above, the command current value for the fuel metering valve is controlled so that the actual fuel pressure in the common rail matches the target fuel pressure, thereby performing fuel pressure feedback control.

  By the way, in this system, it is considered that the sliding resistance of the valve body in the fuel metering valve increases due to some cause such as deposit accumulation, resulting in deterioration of the slidability. If a sliding abnormality occurs due to the deterioration of the slidability in this way, the delay of the follow-up operation of the valve body with respect to the instruction current value to the solenoid coil becomes large, and inconveniences such as hunting of the fuel pressure occur. If this state is left unattended, problems such as poor engine start-up and unstable engine rotation speed during idle operation occur. Therefore, there is a demand for a technique that can detect the sliding abnormality of the valve body in the intake metering valve at an early stage.

  Incidentally, in the pump abnormality diagnosis device disclosed in Patent Document 1, in a high-pressure supply pump having a plurality of pumping systems, the pump pumping amount is estimated and the estimated pump pumping amount is compared with a predetermined determination value. As a result, when the pump pumping amount is excessive or insufficient, it is detected that the corresponding pumping system is abnormal. Alternatively, in a high-pressure supply pump that also has a plurality of pumping systems, when the pump pumping amount is estimated and the previous value of the estimated pump pumping amount is compared with the current value, and as a result, the pump pumping amount is excessive or insufficient In addition, it is detected that the corresponding pumping system is abnormal.

However, the technique of Patent Document 1 described above does not make an abnormality determination regarding the abnormal sliding of the valve body in the fuel metering valve, and it is difficult to detect the abnormal sliding. That is, the above-mentioned patent document detects a pumping system that has become abnormal due to foreign object biting among a plurality of pumping systems, and the followability of the valve body is delayed with respect to the indicated current value to the solenoid coil. It was not possible to detect it suitably.
JP 2004-108171 A

  It is an object of the present invention to provide an abnormality determination device for an accumulator type injection device capable of determining a sliding abnormality of a valve body in a fuel metering valve at an early stage and appropriately, and thus suppressing adverse effects on engine operation. This is the main purpose.

  In the present invention, a control command is output to the fuel metering valve so that the fuel pressure in the common rail becomes a target fuel pressure in a pressure accumulating injector provided with a common rail, a fuel supply pump, and a fuel metering valve. Thus, fuel pressure feedback control is performed. At this time, when a control command is output to the fuel metering valve, the opening of the fuel metering valve is manipulated by sliding of the valve body according to the control command, and fuel pressure feed from the fuel supply pump to the common rail The amount is adjusted.

  The abnormality determination device according to claim 1, wherein the first abnormality determination means is based on the behavior of the fuel pressure in the common rail or the drive current of the fuel metering valve when a predetermined fuel pressure stabilization condition is satisfied. Then, it is temporarily determined that a sliding abnormality of the valve body has occurred. Further, the second abnormality determining means drives the fuel metering valve according to a predetermined abnormality determination control command when the valve abnormality of the valve body is provisionally determined by the first abnormality determining means, Based on the behavior of the fuel pressure at that time or the drive current of the fuel metering valve, it is finally determined that a sliding abnormality of the valve element has occurred.

  The fuel pressure stabilization condition is a condition that is satisfied when the fuel pressure in the common rail is stable, for example, when the engine is in an idle operation state. In other words, the fuel pressure in the common rail is This is a condition that is satisfied when the engine is not in a transient operation state that varies greatly.

In short, if an abnormal sliding of the valve in the fuel metering valve occurs due to deposits, etc., the behavior of the fuel pressure in the common rail and the drive current of the fuel metering valve are different from normal ones as a sign of abnormality. Become. In such a case, according to the first abnormality determining means, it is possible to detect the sliding abnormality of the valve body in the fuel metering valve at an early stage (in the predictive stage) in an idle stable state or the like. However, in this case, it is also conceivable that the fuel pressure fluctuates due to factors other than abnormal sliding of the valve body in the fuel metering valve. In this regard, after the temporary determination by the first abnormality determination unit, the control command is positively operated by the second abnormality determination unit and the final determination is performed, so that the accuracy of the final abnormality determination can be improved. In this case, the second abnormality determining means forcibly operates the control command regardless of the engine operating state at each time (in other words, interrupting the fuel pressure feedback control). Since the general operation is performed only when the provisional determination is made, the influence on the engine operating state or the like can be minimized. As described above, the sliding abnormality of the valve body in the fuel metering valve can be determined at an early stage and appropriately, and as a result, adverse effects on the operation of the engine can be suppressed.
In the second abnormality determination means, it is effective to forcibly change the lift amount of the valve body of the fuel metering valve based on the output of the abnormality determination control command, and to use the behavior of the fuel pressure in response to that as an abnormality determination parameter. It is thought that. In this case, as described in claim 1, a control command that changes stepwise in a predetermined pattern to increase or decrease is output to the fuel metering valve as an abnormality determination control command, and the control command step When the variation amount of the fuel pressure at the time of the change is equal to or greater than the determination threshold value, it is finally determined that the sliding abnormality of the valve body has occurred. Alternatively, as described in claim 2, a control command that changes in a pulse shape is output to the fuel metering valve as the abnormality determination control command, and the amount of change in the fuel pressure when the control command pulse changes is determined. When it is equal to or greater than the threshold value, it is finally determined that a sliding abnormality of the valve body has occurred.
According to the first and second aspects of the present invention, since the abnormality determination is performed based on the behavior of the fuel pressure that should appear originally, the sliding abnormality of the fuel metering valve can be correctly determined.

In the invention according to claim 3 , since the determination threshold value or determination period is set so as to exclude the temporary fluctuation of the fuel pressure due to the disturbance factor and the fluctuation of the driving current of the fuel metering valve, When fluctuations or fluctuations in the drive current of the fuel metering valve occur, it can be discriminated whether it is due to a disturbance factor or a sliding abnormality of the valve body.
In addition, according to a third aspect of the present invention, the first abnormality determining means includes an amplitude amount of a pulsation of fuel pressure in the common rail, an amplitude amount of a drive current of the fuel metering valve, or the fuel metering valve. When the predetermined fuel pressure stabilization condition is satisfied and the abnormality determination parameter is equal to or larger than the set determination threshold value, the offset amount of the drive current is calculated as an abnormality determination parameter. It may be determined that the sliding is abnormal.

In a fourth aspect of the invention, a determination threshold value for abnormality determination is variably set based on the abnormality determination control command. Thereby, the accuracy of abnormality determination can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. The present embodiment embodies the present invention as a common rail fuel injection system for a vehicle diesel engine, and a detailed configuration thereof will be described below.

  FIG. 1 is a configuration diagram showing an outline of a common rail fuel injection system. In FIG. 1, a multi-cylinder diesel engine (hereinafter referred to as an engine) 10 is provided with an electromagnetic injector 11 for each cylinder, and these injectors 11 are connected to a common rail (pressure accumulation pipe) 12 common to each cylinder. A high pressure pump 13 as a fuel supply pump is connected to the common rail 12, and high pressure fuel corresponding to the injection pressure is continuously accumulated in the common rail 12 as the high pressure pump 13 is driven. The high-pressure pump 13 is driven as the engine 10 rotates, and fuel is repeatedly sucked and discharged in synchronization with the engine rotation. The high pressure pump 13 is provided with an electromagnetically driven suction metering valve (SCV) 14 at its fuel suction portion, and the low pressure fuel pumped from the fuel tank 16 by the feed pump 15 passes through the suction metering valve 14. And sucked into the fuel chamber of the pump 13.

  In practice, the high-pressure pump 13, the suction metering valve 14, and the feed pump 15 are integrated into a pump unit. Since the configuration is well known, a detailed description thereof will be omitted, and the configuration will be briefly described here. That is, in the pump unit, a low pressure fuel path and a high pressure fuel path are formed in the housing member, and the feed pump 15 and the intake metering valve 14 are provided in the low pressure fuel path. When the intake metering valve 14 is opened, the low-pressure fuel supplied through the low-pressure fuel path is increased in pressure by the high-pressure pump 13 and the high-pressure fuel is discharged through the high-pressure fuel.

  The common rail 12 is provided with a common rail pressure sensor 17, and the common rail pressure sensor 17 detects a fuel pressure in the common rail 12 (hereinafter also referred to as an actual rail pressure). Although not shown, the common rail 12 is provided with an electromagnetically driven (or mechanical) pressure reducing valve. When the common rail pressure rises excessively, the pressure reducing valve is opened to perform pressure reduction. It has become.

  The ECU 20 is an electronic control unit including a known microcomputer composed of a CPU, ROM, RAM, EEPROM, and the like. The ECU 20 includes a rotation signal for detecting the rotation speed of the engine in addition to the detection signal of the common rail pressure sensor 17. Detection signals are sequentially input from various sensors such as a speed sensor, an accelerator opening sensor that detects the amount of accelerator operation by the driver, a water temperature sensor that detects the temperature of engine cooling water, and a fuel temperature sensor that detects the fuel temperature in the common rail 12. The Then, the ECU 20 determines an optimal fuel injection amount and injection timing based on engine operation information such as the engine rotation speed and the accelerator opening, and outputs an injection control signal corresponding to the fuel injection amount to the injector 11. Thus, fuel injection from the injector 11 to the combustion chamber is controlled in each cylinder.

  Further, the ECU 20 calculates a target value of the common rail pressure (injection pressure) based on the engine speed and the fuel injection amount at that time, and sets the fuel discharge amount of the high-pressure pump 13 so that the actual rail pressure becomes the target rail pressure. Feedback control. Actually, the target discharge amount of the high-pressure pump 13 is determined based on the deviation between the actual rail pressure and the target rail pressure, and the opening degree of the intake metering valve 14 is controlled accordingly. At this time, by controlling the command current value (drive current) for the electromagnetic solenoid of the suction metering valve 14, the opening of the suction metering valve 14 is increased or decreased, and the fuel discharge amount by the high-pressure pump 13 is adjusted accordingly. The

  Here, the configuration of the intake metering valve 14 will be described with reference to FIG. The intake metering valve 14 is configured as a normally open valve that is held in an open state (fully open state) when the electromagnetic solenoid is not energized, and increases the indicated current value to the electromagnetic solenoid to open the fuel intake passage. The area is increased. Thereby, the fuel intake amount of the high-pressure pump 13 is increased, and as a result, the fuel discharge amount by the high-pressure pump 13 is increased.

  In the intake metering valve 14, a valve body 32 as a spool is slidably accommodated in a substantially cylindrical valve case 31. The valve body 32 is formed with a fuel introduction path 33 extending in the axial direction and a plurality of communication paths 34 extending in the radial direction. Low pressure fuel is introduced from the feed pump 15 into the fuel introduction path 33. A plurality of flow paths 35 are formed in the valve case 31. In this case, the valve body 32 is urged to the left in the figure by the spring 36, and in the state shown in the figure, the flow path 35 of the valve case 31 and the communication path 34 of the valve body 32 are in communication (intake metering). The valve 14 is fully open). As a result, the low pressure fuel introduced into the fuel introduction passage 33 from the tip end portion (left end portion in the figure) of the intake metering valve 14 is supplied to the high pressure pump 13 side through the communication portion between the communication passage 34 and the flow passage 35. Is done.

  A housing 38 is assembled to the valve case 31, and a solenoid 39 is accommodated in an annular space formed between the valve case 31 and the housing 38. Reference numeral 40 in the figure is a connector portion for supplying an energization signal to the solenoid 39.

  In the intake metering valve 14 configured as described above, when the solenoid 39 is energized, the valve body 32 moves in the right direction in the figure against the urging force of the spring 36, and the valve of the intake metering valve 14 correspondingly. Opening is reduced. At this time, the valve opening degree of the intake metering valve 14 is adjusted according to the command current value for the solenoid 39, and the larger the command current value, the more the valve opening is reduced and the fuel suction amount is reduced. . In the present embodiment, in particular, a duty drive signal is output to the intake metering valve 14 (solenoid 39) at a predetermined drive frequency, and the command current value is controlled by the duty drive signal. The drive frequency of the intake metering valve 14 is about 250 Hz, for example.

  By the way, in the intake metering valve 14, it is considered that the sliding resistance of the valve body 32 increases due to deposits and the like accompanying long-term use, resulting in a sliding abnormality. If the sliding abnormality occurs in this way, the delay of the follow-up operation of the valve body 32 with respect to the energization signal to the solenoid 39 becomes large, and inconveniences such as hunting of the actual rail pressure occur. This causes inconveniences such as an engine start failure or an unstable engine rotation speed during idle operation.

  FIG. 3 is a time chart showing the relationship between the drive current of the intake metering valve 14 (hereinafter referred to as the SCV drive current) and the lift operation of the valve body 32. FIG. (B) shows a case where a sliding abnormality of the valve body 32 occurs.

  In the case of (a), the valve lift amount changes following the periodic change of the SCV drive current. Specifically, the valve body lift amount increases in response to an increase in SCV drive current, and the valve body lift amount decreases in response to a decrease in SCV drive current. On the other hand, in the case of (b), the periodic change in the valve body lift amount does not follow the change in the SCV drive current, and the amount of change varies greatly. If the valve lift amount does not follow the SCV drive current in this way, an event such as an excessive increase in the actual rail pressure (swell) occurs.

  Therefore, in the present embodiment, a sliding abnormality of the intake metering valve 14 is determined using the fluctuation amount of the actual rail pressure as an abnormality determination parameter. In particular, the abnormality determination is performed in two stages, a temporary determination stage and a final determination stage. First, when the fuel pressure stabilization condition is satisfied, such as when the engine is in an idling stable state, the actual rail pressure Based on the fluctuation amount, a provisional determination of a sliding abnormality is performed, and then the instruction current value for the suction metering valve 14 (solenoid 39) is forcibly increased or decreased in a predetermined pattern, and the fluctuation amount of the actual rail pressure at that time Based on the above, the final determination of the sliding abnormality is performed.

  FIG. 4 is a flowchart showing a sliding abnormality determination process of the intake metering valve 14, and this process is repeatedly executed by the ECU 20 at a predetermined time period.

  In FIG. 4, in step S101, it is determined whether or not the current engine operation state is an idle stable state. For example, when the accelerator opening (or even the throttle opening) is 0 and the idle rotation speed is in a predetermined rotation range, it is determined that the idle stable state is established. In the subsequent step S102, it is determined whether or not a predetermined sliding abnormality determination condition is satisfied. Specifically, the sliding abnormality determination condition includes that the water temperature and the fuel temperature are within a predetermined temperature range, and that the final injection amount is within a predetermined range.

  If either step S101 or S102 is not established, the present process is terminated as it is. If both steps S101 and S102 are established, the process proceeds to step S103.

  In step S103, it is determined whether or not provisional determination processing for sliding abnormality has not been performed after both of steps S101 and S102 have been established this time. Then, if it has not been performed, the process proceeds to step S104, and the provisional determination process of the sliding abnormality of the intake metering valve 14 is performed. If the sliding abnormality provisional determination processing has been performed, step S104 is skipped and the process proceeds to step S105.

  Details of the provisional determination process will be described with reference to a subroutine shown in FIG. In FIG. 5, in step S <b> 201, ΔPc calculation processing for calculating the actual rail pressure fluctuation amount (pressure fluctuation amount ΔPc) is performed. At this time, whenever the actual rail pressure pulsates and reaches the peak value or the bottom value, the peak value or the bottom value is sequentially obtained, and the pressure fluctuation amount ΔPc is calculated from the pressure difference. Next, in step S202, it is determined whether or not the pressure fluctuation amount ΔPc for one cycle has been calculated. At this time, if the actual rail pressure is midway or midway, step S202 is negatively determined, the actual rail pressure becomes a peak value (or bottom value), and the pressure fluctuation amount ΔPc is calculated from a set of peak value and bottom value. If so, step S202 is positively determined.

  If the pressure fluctuation amount ΔPc for one cycle is calculated, it is determined in step S203 whether or not the pressure fluctuation amount ΔPc is equal to or greater than a predetermined determination value K1. If ΔPc <K1, it is considered that no sliding abnormality has occurred in the intake metering valve 14, and after the abnormality determination counter is cleared to 0 in step S204, this process is terminated.

  On the other hand, if ΔPc ≧ K1, the process proceeds to step S205, where the abnormality determination counter CNT1 is incremented by 1. In subsequent step S206, it is determined whether or not the value of the abnormality determination counter CNT1 is equal to or greater than a predetermined determination value K2. If CNT1 ≧ K2, the process proceeds to step S207, where it is temporarily determined that a sliding abnormality of the intake metering valve 14 has occurred, and in response, 1 is set to the temporary determination flag Ferr1.

  The determination values K1 and K2 in steps S203 and S206 are set to values that eliminate erroneous determination due to disturbance factors. That is, when a disturbance due to electric noise or air mixing in the fuel path occurs, the actual rail pressure fluctuates temporarily due to the disturbance, but the pressure fluctuation is not continuous. In this case, erroneous determination due to disturbance factors can be avoided by determination using the determination values K1 and K2.

  The provisional determination process of FIG. 5 will be described more specifically with reference to FIG. When a sliding abnormality of the intake metering valve 14 has occurred, as shown in FIG. 7, the fluctuation of the actual rail pressure with respect to the target rail pressure increases. At this time, the pressure fluctuation amount ΔPc of the actual rail pressure becomes equal to or greater than the determination value K1, and the state is continued. When the continuation time reaches a provisional determination time (a time corresponding to the determination value K2), it is temporarily determined that a sliding abnormality of the intake metering valve 14 has occurred.

  Returning to the description of FIG. 4, in step S <b> 105, it is determined whether or not the temporary determination flag Ferr <b> 1 is 1, that is, whether or not it is temporarily determined that a sliding abnormality of the intake metering valve 14 has occurred. If Ferr1 = 0, the process is terminated as it is. If Ferr1 = 1, the process proceeds to the subsequent step S106. In step S106, a final determination process for abnormal sliding of the intake metering valve 14 is performed.

  Details of the final determination process will be described with reference to a subroutine shown in FIG. In the process of FIG. 6, the instruction current value of the intake metering valve 14 is actively operated to increase or decrease every predetermined time, and the sliding abnormality of the intake metering valve 14 is determined based on the fluctuation amount of the actual rail pressure. Is finally determined.

  In FIG. 6, in step S301, it is determined whether or not this time is the timing to change the command current value of the intake metering valve 14 stepwise (stepwise). The indicated current value at the time is changed to the increase side or the decrease side by a predetermined amount α. At this time, the control command for changing the command current value corresponds to an “abnormality determination control command”.

  After that, in each step subsequent to step S303, the sliding abnormality of the intake metering valve 14 is finally determined using the actual rail pressure fluctuation amount (pressure fluctuation amount ΔPc) as the abnormality judgment parameter for each command current value operated in multiple stages. To do. In addition, each process of step S303-S309 is based on the process of FIG. 5 mentioned above, and description is simplified about the overlapping process.

  In step S303, the pressure fluctuation amount ΔPc is calculated, and the pressure fluctuation amount ΔPc for one cycle is calculated (step S304 is YES). In step S305, the pressure fluctuation amount is calculated. It is determined whether ΔPc is equal to or greater than a predetermined determination value K3. If ΔPc <K3, it is considered that there is no sliding abnormality of the intake metering valve 14, and after the abnormality determination counter is cleared to 0 in step S306, this process is terminated.

  On the other hand, if ΔPc ≧ K3, the process proceeds to step S307, where the abnormality determination counter CNT2 is incremented by 1. In subsequent step S308, it is determined whether or not the value of the abnormality determination counter CNT2 is equal to or greater than a predetermined determination value K4. If CNT2 ≧ K4, the process proceeds to step S309, where it is finally determined that a sliding abnormality of the intake metering valve 14 has occurred, and 1 is set to the final determination flag Ferr2 accordingly.

  Note that the determination value K3 in step S305 is variably set according to the indicated current value. At this time, the determination value K3 is set to a larger value as the amount of change from the current value before the instruction current value is changed stepwise is larger. Thereby, the accuracy of abnormality determination can be improved. However, the determination value K3 can be a fixed value.

The provisional determination process of FIG. 6 will be described more specifically with reference to FIG. In FIG. 8, as the change pattern of the command current value, the command current value is decreased by a predetermined amount α in two stages and then returned to the original command current value in two stages. However, the amount of change at each step change is arbitrary.

  In this case, the command current value is operated in a stepwise manner every predetermined time, and if the intake metering valve 14 is normal, the fuel discharge amount by the high-pressure pump 13 is stabilized and corresponds to the command current value. The actual rail pressure changes. On the other hand, when a sliding abnormality of the intake metering valve 14 occurs, the fuel discharge amount by the high-pressure pump 13 becomes unstable, and the fluctuation of the actual rail pressure increases. At this time, the state in which the pressure fluctuation amount ΔPc of the actual rail pressure is equal to or greater than the determination value K3 is continued, and it is finally determined that a sliding abnormality of the intake metering valve 14 has occurred.

  Returning to the description of FIG. 4 again, in step S107, it is determined whether or not the final determination flag Ferr2 is 1, that is, whether or not the final determination is made that a sliding abnormality of the intake metering valve 14 has occurred. . If Ferr2 = 0, the process is terminated as it is. If Ferr2 = 1, the process proceeds to the subsequent step S108. In step S108, a predetermined fail-safe process corresponding to the sliding abnormality of the intake metering valve 14 is appropriately performed. Specifically, the target rail pressure is reduced and corrected so as to suppress an excessive increase in the common rail pressure due to sliding failure, or failure diagnosis information (diag code, etc.) indicating the occurrence of an abnormality is read from the EEPROM or backup RAM in the ECU 20. Or a warning lamp (so-called MIL lamp) is turned on. In this case, the occurrence of an abnormality can be notified to the driver or the like by turning on the warning lamp, and the dealer or the like can suitably repair or replace the abnormal part by analyzing the failure diagnosis information.

  In addition, the provisional determination process (FIG. 5) and the final determination process (FIG. 6) of the sliding abnormality are performed within the establishment period of each condition of steps S101 and S102, and during the execution of each abnormality determination process. Once the above conditions are not satisfied, the abnormality determination process is interrupted at that time, and normal fuel pressure feedback control is resumed. In that case, the counter value and the like are cleared.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

  In determining the sliding abnormality of the intake metering valve 14, the abnormality determination is performed in two stages of a temporary determination and a final determination. Therefore, the sliding abnormality can be detected early (at the sign stage), and finally The accuracy of abnormality determination can be improved. In this case, at the time of the final determination, the control command is forcibly operated regardless of the engine operating state at each time (in other words, the fuel pressure feedback control is interrupted). Since this is implemented only when the operation is performed, the influence on the engine operating state or the like can be minimized. As described above, a sliding abnormality of the intake metering valve 14 can be determined at an early stage and appropriately, and as a result, adverse effects on engine operation can be suppressed.

  In this case, it can be determined that a sliding abnormality of the intake metering valve 14 has occurred when the idle rotation becomes unstable, and a fail-safe process is activated at a stage before the engine starts poorly. Appropriate measures can be taken.

  At the time of the final determination, the command current value is increased or decreased in steps, and the sliding abnormality of the intake metering valve 14 is determined based on the behavior of the actual rail pressure in response thereto. Therefore, it is possible to correctly determine the sliding abnormality of the intake metering valve 14.

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  In the above embodiment, in the provisional determination process of the sliding abnormality (the process of FIG. 5), when the actual rail pressure fluctuation amount (pressure fluctuation amount ΔPc) is equal to or greater than a predetermined value and the state continues for a predetermined time, Although it is temporarily determined that a sliding abnormality of the intake metering valve 14 has occurred, this is changed as follows. That is, as shown in FIG. 9, the upper limit allowable value Pmax and the lower limit allowable value Pmin of the actual rail pressure are determined with reference to the target rail pressure, and accompanying the fluctuation of the actual rail pressure in the provisional determination process of the sliding abnormality When the maximum rail pressure exceeds the upper limit allowable value Pmax, or when the minimum rail pressure falls below the lower limit allowable value Pmin, it is temporarily determined that a sliding abnormality of the intake metering valve 14 has occurred. At this time, the number of times that the maximum rail pressure> the upper limit allowable value Pmax or the minimum rail pressure <the lower limit allowable value Pmin is counted, and when the number reaches the predetermined value, a sliding abnormality of the intake metering valve 14 occurs. It is also possible to tentatively determine that it is in progress. Similarly, in the final determination of the sliding abnormality, it is also possible to perform an abnormality determination based on the actual rail pressure exceeding the upper limit allowable value Pmax (or the lower limit allowable value Pmin).

  As described above, when the sliding abnormality of the intake metering valve 14 occurs, the fluctuation amount (swell) of the actual rail pressure is excessively increased due to a decrease in the follow-up performance of the valve body. As shown in FIG. 10 (a), the fluctuation amount of the SCV driving current becomes excessively large. As shown in FIG. 10 (b), the fluctuation center of the SCV driving current is offset to the positive side or the negative side. It is thought that such an event occurs. Therefore, abnormality determination (temporary determination and final determination) is performed using the variation amount of the SCV drive current as an abnormality determination parameter, or abnormality determination (temporary determination and final determination) is performed using the offset amount of the fluctuation center of the SCV drive current as an abnormality determination parameter. (Determination) may be performed.

  In FIG. 10A, when the variation amount ΔI of the SCV drive current is equal to or greater than the determination value Ka and the duration time reaches a predetermined time, a sliding abnormality of the intake metering valve 14 has occurred. A provisional determination (or final determination) is made. Further, in FIG. 10B, a provisional determination (or a determination that a sliding abnormality of the intake metering valve 14 has occurred at the time when the offset amount at the fluctuation center of the SCV drive current becomes equal to or greater than a predetermined determination value (or Final decision) is made.

  Further, in the provisional determination and final determination regarding the sliding abnormality of the intake metering valve 14, the abnormality determination may be performed using different abnormality determination parameters. For example, the SCV drive current is used as an abnormality determination parameter in the temporary determination, and the fluctuation amount of the actual rail pressure is used as the abnormality determination parameter (or vice versa) in the final determination.

  In the final determination process of the sliding abnormality, the fuel injection pulse of the injector 11 is preferably set to a fixed length in order to prevent the common rail pressure from excessively increasing when the command current value is increased or decreased in steps. Thereby, the damage of the high-pressure pump 13 caused by the excessive increase in the common rail pressure in the idling operation state is reduced. The fixed pulse length of the fuel injection pulse may be determined by correcting the basic pulse length assumed under the idle operation state in accordance with the instruction current value each time. Alternatively, it may be determined by correcting the pulse length before the step change of the command current value according to the command current value each time.

  Instead of the configuration in which the command current value is changed in a step shape in the final determination process of the sliding abnormality, the command current value may be changed in a pulse shape. Specifically, as shown in FIG. 11, the command current value is temporarily changed by a predetermined amount β, and the sliding abnormality determination is performed based on the behavior of the actual rail pressure at that time. At this time, if the intake metering valve 14 is normal, the fuel discharge amount by the high-pressure pump 13 is stabilized, and the actual rail pressure changes corresponding to the command current value. On the other hand, when a sliding abnormality of the intake metering valve 14 occurs, the fuel discharge amount by the high-pressure pump 13 becomes unstable, and the fluctuation of the actual rail pressure increases. Therefore, it is possible to finally determine that a sliding abnormality of the intake metering valve 14 has occurred.

  Note that the number of changes in current value, the amount of change, the interval, and the like are arbitrarily set when the command current value is changed in pulses. It is also possible to adopt a configuration in which the amount of change in current is changed each time the command current value is changed in a pulse shape.

  In the above-described embodiment, the high-pressure pump 13 is configured to include the intake metering valve 14 as the fuel metering valve in the fuel suction path, and the sliding abnormality is determined for the suction metering valve 14, but this is changed. . For example, a discharge metering valve as a fuel metering valve may be provided in the fuel discharge path of the high-pressure pump 13, and a sliding abnormality may be determined for this discharge metering valve. In any case, according to the present invention, it is possible to suitably determine whether or not the fuel metering valve slides abnormally.

It is a lineblock diagram showing an outline of a common rail type fuel injection system in an embodiment of the invention. It is sectional drawing which shows the structure of an intake metering valve. It is a time chart which shows the relationship between SCV drive current and valve body lift operation | movement. It is a flowchart which shows the sliding abnormality determination process of an intake metering valve. It is a flowchart which shows the temporary determination process of sliding abnormality. It is a flowchart which shows the final determination process of sliding abnormality. It is a time chart which shows the mode of the fluctuation | variation of the actual rail pressure at the time of sliding abnormality of an intake metering valve. It is a time chart which shows the behavior of the actual rail pressure when changing the command current value stepwise. It is a time chart which shows the mode of the fluctuation | variation of the actual rail pressure at the time of sliding abnormality of an intake metering valve. It is a time chart which shows the mode of the fluctuation | variation of the SCV drive current at the time of the sliding abnormality of an intake metering valve. It is a time chart which shows the behavior of the actual rail pressure when changing the command current value in a pulse shape.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Common rail, 13 ... High pressure pump, 14 ... Suction metering valve, 20 ... ECU, 32 ... Valve body.

Claims (4)

A common rail for accumulating fuel at a high fuel pressure corresponding to the injection pressure, a fuel supply pump for pumping high-pressure fuel to the common rail, and a valve body provided in a fuel intake path or a fuel discharge path of the fuel supply pump. An electromagnetic fuel metering valve that adjusts the fuel flow rate by opening operation associated with sliding, and a control command is output to the fuel metering valve so that the fuel pressure in the common rail becomes a target fuel pressure Applied to a pressure-accumulation type injection device in which fuel pressure feedback control is performed,
When a predetermined fuel pressure stabilization condition is satisfied, a provisional determination is made that a sliding abnormality of the valve element has occurred based on the behavior of the fuel pressure in the common rail or the drive current of the fuel metering valve. 1 abnormality determination means;
When the sliding abnormality of the valve body is provisionally determined by the first abnormality determining means, the fuel metering valve is driven by a predetermined abnormality determining control command, and based on the behavior of the fuel pressure at that time Second abnormality determining means for finally determining that a sliding abnormality of the valve body has occurred;
With
The second abnormality determination means outputs a control command that changes stepwise in a predetermined pattern to increase or decrease as the abnormality determination control command to the fuel metering valve, and step change of the control command An abnormality determination device for a pressure-accumulation type injection device, wherein a final determination is made that a sliding abnormality of the valve element has occurred when a fuel pressure fluctuation amount at a time is equal to or greater than a determination threshold value . A common rail for accumulating fuel at a high fuel pressure corresponding to the injection pressure, a fuel supply pump for pumping high-pressure fuel to the common rail, and a valve body provided in a fuel intake path or a fuel discharge path of the fuel supply pump. An electromagnetic fuel metering valve that adjusts the fuel flow rate by opening operation associated with sliding, and a control command is output to the fuel metering valve so that the fuel pressure in the common rail becomes a target fuel pressure Applied to a pressure-accumulation type injection device in which fuel pressure feedback control is performed,
When a predetermined fuel pressure stabilization condition is satisfied, a provisional determination is made that a sliding abnormality of the valve element has occurred based on the behavior of the fuel pressure in the common rail or the drive current of the fuel metering valve. 1 abnormality determination means;
When the sliding abnormality of the valve body is provisionally determined by the first abnormality determining means, the fuel metering valve is driven by a predetermined abnormality determining control command, and based on the behavior of the fuel pressure at that time Second abnormality determining means for finally determining that a sliding abnormality of the valve body has occurred;
With
The second abnormality determination means outputs a control command that changes in a pulse shape as the abnormality determination control command to the fuel metering valve, and determines the amount of change in the fuel pressure when the control command pulse changes. An abnormality determination device for a pressure-accumulation type injection device , wherein when it is equal to or greater than a threshold value, it is finally determined that a sliding abnormality of the valve body has occurred . The first abnormality determination means sets a determination threshold value that excludes a temporary fuel pressure fluctuation due to a disturbance factor or a fluctuation in the driving current of the fuel metering valve, and the fuel pressure in the common rail is set. A case where the predetermined fuel pressure stabilization condition is satisfied by obtaining an amplitude amount of pulsation, an amplitude amount of the drive current of the fuel metering valve, or an offset amount of the drive current of the fuel metering valve as an abnormality determination parameter. The abnormality determination of the pressure-accumulation injection device according to claim 1 or 2, wherein when the abnormality determination parameter is equal to or more than the set determination threshold, a sliding abnormality of the valve body is temporarily determined. apparatus. The pressure-accumulation injection according to any one of claims 1 to 3, wherein the second abnormality determination means variably sets a determination threshold value for abnormality determination based on the abnormality determination control command. Device abnormality determination device.

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