JP4577165B2 - Abnormality diagnosis device for fuel injection device - Google Patents

Description

  The present invention provides a fuel injection system comprising a pressure accumulation chamber for storing fuel in a high pressure state, a fuel pump for pressurizing and supplying fuel in the pressure accumulation chamber, and a fuel injection valve for injecting fuel stored in the pressure accumulation chamber in a high pressure state The present invention relates to an abnormality diagnosis device for a fuel injection device for diagnosing the presence or absence of an abnormality of the device.

  As this type of abnormality diagnosis device, for example, as seen in Patent Document 1 below, based on the difference between the amount of fuel flowing out from the common rail and the amount of entering fuel flowing into the common rail, the fuel pump to the fuel injection valve Some have been proposed for diagnosing the presence or absence of fuel leakage in the fuel path. Specifically, the fuel output amount is estimated based on the amount of fuel leaked from the fuel injection valve, the fuel injection amount, etc., and the amount of incoming fuel is estimated as the fuel pump discharge amount based on the energization start timing for the fuel pump, The presence / absence of fuel leakage abnormality is diagnosed from the difference between the estimated fuel output amount and the discharge amount.

  By the way, the abnormality of the fuel path of the fuel injection device is not limited to that in which fuel leakage occurs due to a hole in the fuel path from the fuel pump to the fuel injection valve. For example, there is an abnormality in which the filter is clogged when the fuel pump pumps up the fuel. In this case, since the discharge amount is small relative to the energization amount of the fuel pump, control for increasing the command discharge amount to the fuel pump is performed. However, in this case, the abnormality diagnosis device determines that the discharge amount (command discharge amount) is excessive with respect to the fuel output amount, and makes an erroneous determination that the fuel leaks.

Note that the abnormality diagnosing device is still unsatisfactory in properly diagnosing various abnormalities of the fuel injection device, not limited to the clogging of the filter.
JP 2004-324416 A

  The present invention has been made to solve the above problems, and an object thereof is to provide an abnormality diagnosis device for a fuel injection device that can more appropriately diagnose the presence or absence of abnormality of the fuel injection device. .

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

The invention according to claim 1 is a pressure accumulating chamber for storing fuel in a high pressure state, a fuel pump for pressurizing and supplying fuel in the pressure accumulating chamber, a fuel injection valve for injecting fuel stored in the pressure accumulating chamber in a high pressure state, In the abnormality diagnosis device for a fuel injection device for diagnosing the presence or absence of abnormality, a control means for feedback-controlling the fuel pressure in the pressure accumulating chamber to a target fuel pressure by operating the fuel pump, and the fuel injection Setting means for variably setting a reference value that is an operation amount of the fuel pump assumed when there is no abnormality in the apparatus based on an amount of fuel flowing out from the pressure accumulating chamber , an actual operation amount by the control means, and the reference value And diagnosing means for diagnosing the presence or absence of an inadequate entry amount in which the discharge amount of the fuel pump is reduced instead of the operation amount.

  In the above configuration, the fuel pressure in the pressure accumulating chamber is feedback-controlled to the target fuel pressure by the control means. If there is no abnormality in the fuel injection device, the operation amount at the time of feedback control is an amount that compensates for fluctuations in the fuel pressure in the pressure accumulating chamber due to fuel injection by the fuel injection valve. For this reason, the reference value of the manipulated variable can be set on the assumption that there is no abnormality in the fuel injection device. If the actual operation amount deviates from the reference value, it is considered that there is an abnormality in the fuel injection device. However, it is difficult to determine what abnormality is in the fuel injection device only from the difference between the actual operation amount and the reference value.

Here, in the above configuration, paying attention to the fact that the increasing speed of the difference differs depending on the type of abnormality of the fuel injection device, a diagnostic means for diagnosing the presence or absence of the insufficient entry amount based on the increasing speed is provided. Prepare. For this reason, according to the said structure, the presence or absence of abnormality of a fuel-injection apparatus can be diagnosed more appropriately.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the setting means estimates a leaked fuel amount that leaks through the fuel injection valve, and the estimated leak The reference value is set each time based on the sum of the fuel amount and the fuel amount injected through the fuel injection valve.

  As described above, if there is no abnormality in the fuel injection device, the operation amount during the feedback control is an amount that compensates for fluctuations in the fuel pressure in the pressure accumulating chamber due to fuel injection by the fuel injection valve. For this reason, this manipulated variable changes in accordance with the amount to compensate for the fluctuation. In this regard, according to the above configuration, by setting the reference value each time based on the leaked fuel amount and the injection amount, the reference value is an appropriate value as an operation amount that is assumed when there is no abnormality in the fuel injection device. Can be set to

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the fuel per unit time of the fuel pump is determined by the diagnostic means when the shortage of the entry amount is determined. Further, a fail-safe means for limiting the amount of inhalation is further provided.

  In the above configuration, when the amount of fuel is insufficient, an increase in the force applied to the fuel pump can be suppressed by limiting the amount of fuel sucked per unit time by the fuel pump.

According to a third aspect of the present invention, there is provided a pressure accumulation chamber for storing fuel in a high pressure state, a fuel pump for pressurizing and supplying fuel in the pressure accumulation chamber, a fuel injection valve for injecting fuel stored in the pressure accumulation chamber in a high pressure state, In the abnormality diagnosis device for a fuel injection device for diagnosing the presence or absence of abnormality, a control means for feedback-controlling the fuel pressure in the pressure accumulating chamber to a target fuel pressure by operating the fuel pump, and the fuel injection Setting means for variably setting a reference value that is an operation amount of the fuel pump assumed when there is no abnormality in the apparatus based on an amount of fuel flowing out from the pressure accumulating chamber , an actual operation amount by the control means, and the reference value Diagnostic means for diagnosing the presence or absence of abnormality of the fuel injection device based on a temporal change in the difference between the actual operating amount and the reference value. The pattern is determined by comparing with a predetermined pattern, and the pattern is a pattern assumed when the amount of discharge of the fuel pump is reduced instead of the operation amount, and the fuel Including a pattern assumed when the amount of fuel flowing out from the fuel path between the pump and the fuel injection valve is abnormal, and the pattern when the amount of fuel is excessive is greater than that when the amount of fuel is insufficient The time change rate is set to be high.

  When the output amount becomes excessive due to a hole in the fuel path or the like, the control means tries to compensate for this, so the difference between the manipulated variable and the reference value increases rapidly. On the other hand, when the above amount is insufficient, this abnormality is caused by clogging of the filter that filters the fuel when the fuel pump pumps up the fuel, and the increase rate of the difference between the manipulated variable and the reference value is It tends to be small. In this regard, according to the above configuration, it is possible to appropriately determine when the amount of filling is insufficient or when the amount of dispensing is excessive.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the setting means includes a rotational speed of an internal combustion engine on which the fuel injection device is mounted, a total operating time of the internal combustion engine, The reference value is variably set according to at least one of the temperature of the fuel in the fuel pump and the fuel pressure in the pressure accumulating chamber.

  In the above configuration, the higher the fuel pressure in the pressure accumulator chamber, the greater the amount of leaked fuel that leaks through the fuel injection valve. Further, the higher the temperature of the fuel in the fuel pump, the lower the viscosity of the fuel, so the amount of leaked fuel that leaks through the fuel injection valve increases. Further, if the fuel pump is of an engine drive type to which a driving force is applied from the output shaft of the internal combustion engine, the discharge amount of the fuel pump per unit time varies depending on the rotation speed of the output shaft. The change in the discharge amount per unit time causes a change in the leaked fuel amount per unit time. Furthermore, if the total operating time is long, the amount of leaked fuel may increase with the aging of the fuel injection valve.

In this regard, in the above configuration, even if the amount of fuel pump operation changes due to an increase in the amount of leaked fuel due to such factors, the change due to this change can be removed from the increase speed . For this reason, according to the said structure, the presence or absence of abnormality can be diagnosed more accurately.

(First embodiment)
Hereinafter, a first embodiment in which an abnormality diagnosis device for a fuel injection device according to the present invention is applied to a fuel injection device for a diesel engine will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the engine system according to the present embodiment.

  As shown in the figure, the fuel in the fuel tank 2 is pumped up by the fuel pump 6 through the fuel filter 4. The fuel pump 6 is powered by a crankshaft 8 that is an output shaft of a diesel engine and discharges fuel. Specifically, the fuel pump 6 includes a fuel metering valve 10, and the fuel metering valve 10 is operated to determine the amount of fuel discharged to the outside. The fuel pump 6 includes several plungers, and the plunger reciprocates between the top dead center and the bottom dead center, whereby fuel is sucked and discharged.

  The fuel from the fuel pump 6 is pressurized and supplied (pressure fed) to the common rail 12. The pumped fuel is stored in a high pressure state in the common rail 12 and supplied to the fuel injection valve 16 of each cylinder (here, four cylinders are illustrated) via the high pressure fuel passage 14. The fuel injection valve 16 is connected to the fuel tank 2 via a low pressure fuel passage 18.

  The engine system includes a fuel pressure sensor 20 that detects the fuel pressure in the common rail 12, a fuel temperature sensor 22 that detects the temperature of the fuel in the fuel pump 6, a crank angle sensor 24 that detects the rotation angle of the crankshaft 8, and the like. Various sensors are provided for detecting the operating state of the engine and the operating environment. The engine system also includes an accelerator sensor 26 that detects an operation amount of an accelerator pedal operated in response to a user's acceleration request. The engine system further includes a display 28 for displaying visual information.

  On the other hand, the electronic control unit (ECU 30) is mainly composed of a microcomputer and includes various memories such as a nonvolatile memory 32. The non-volatile memory 32 includes, for example, a backup RAM to which power is supplied regardless of whether or not power is supplied to the ECU 30, a type of memory (EEPROM or the like) that holds data regardless of whether or not power is supplied. And ECU30 takes in the detection result of the said various sensors, and controls the output of a diesel engine based on this.

  In order to appropriately perform the output control, the ECU 30 performs fuel injection control. In this fuel injection control, the fuel pressure in the common rail 12 is feedback-controlled to a target fuel pressure that is set according to the operating state and operating environment of the diesel engine.

  FIG. 2 shows a processing procedure of the feedback control. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processing, first, in step S10, the operation amount of the accelerator pedal detected by the accelerator sensor 26 and the rotational speed of the crankshaft 8 detected by the crank angle sensor 24 are captured. In step S12, the target fuel pressure in the common rail 12 is calculated based on the operation amount of the accelerator pedal and the rotational speed. In subsequent step S14, the detected value of the fuel pressure by the fuel pressure sensor 20 is captured. In step S16, the fuel pump 6 (the fuel metering valve 10) is operated to feedback control the detected value of the fuel pressure to the target fuel pressure. Here, for example, the operation current value of the fuel metering valve 10 may be calculated by PID control, and the fuel metering valve 10 may be operated with the calculated operation current value. In addition, when the process of step S16 is completed, this series of processes is once complete | finished.

  The ECU 30 further has a function of diagnosing the presence or absence of abnormality of the fuel injection device configured to include the fuel filter 4, the fuel pump 6, the common rail 12, and the fuel injection valve 16. This will be described below.

  The diagnosis is performed by paying attention to a deviation amount between an operation current value assumed when there is no abnormality in the fuel injection device and an actual operation current value by the feedback control shown in FIG. Here, first, the value of the operation current value by the feedback control will be considered.

  Factors that cause the fuel pressure in the common rail 12 to vary include the following.

  Static leak: a phenomenon in which the fuel leaks from the high pressure fuel passage 14 to the low pressure fuel passage 18 through the fuel injection valve 16 when fuel injection through the fuel injection valve 16 is not performed.

  Dynamic leak: a phenomenon in which, when fuel is injected through the fuel injection valve 16, the fuel leaks from the high pressure fuel passage 14 to the low pressure fuel passage 18 through the fuel injection valve 16.

  Injection of fuel through the fuel injection valve 16.

  The fuel is pumped by the fuel pump 6.

  Here, by setting the discharge amount of the fuel pump 6 to an amount (compensation amount) that compensates for all of static fuel leak, dynamic leak, fuel injection, and target fuel pressure change, the fuel pressure in the common rail 12 is reduced. The target fuel pressure can be set. For this reason, it is considered that the operation current value of the fuel metering valve 10 is set to a value having the discharge amount of the fuel pump 6 as the compensation amount by the feedback control shown in FIG. However, when there is an abnormality in the fuel injection device, it is considered that the operation amount deviates from the compensation amount.

  FIG. 3A shows a case where the fuel metering valve 10 is a normally closed type, and FIG. 3B shows a case where the fuel metering valve 10 is a normally open type. The operating current value of the fuel metering valve 10 is shown. 3 (a) and 3 (b) both show the operation current value required by the feedback control of FIG. 2 when the discharge amount of the fuel pump 6 is the compensation amount.

  In the figure, for the fuel pump 6 having the central characteristic value, the operation current value required by the feedback control shown in FIG. Here, the central characteristic value is an average of variations in discharge characteristics due to individual differences that are allowed when the fuel pump 6 is manufactured. A broken line a ′ indicates an upper limit and a lower limit of the variation in the operation current value due to the variation in ejection characteristics due to the individual difference and the secular change. On the other hand, a solid line b indicates an operation current value at the time of a shortage of the input amount in which the discharge amount decreases instead of the operation current value of the fuel pump 6 due to, for example, clogging in the fuel filter 4. In addition, a solid line c indicates an operation current value at the time of excessive output that causes fuel leakage due to, for example, a hole formed between the outlet of the fuel pump 6 and the fuel injection valve 16. Incidentally, in the figure, the limit value ΔIa is the limit value of the deviation amount when the operating current value deviates from that in the fuel pump 6 having the central characteristic value due to the discharge characteristic variation due to individual differences or aging.

  As shown in the figure, the operation current value is different for both the shortage of the input amount and the excessive value of the output amount compared to the normal state. Furthermore, the time change of the difference between the operation current value required when there is no abnormality in the fuel injection device and the actual operation current value when the input amount is insufficient and when the output amount is excessive is shown in FIG. It will be different as illustrated for the formula.

  FIG. 4A shows a deviation amount ΔI from the operating current value required for the fuel pump 6 having the central characteristic value by feedback control when the fuel injection device is normal. In this case, the deviation ΔI from the operating current value for the fuel pump 6 having the central characteristic value is within the limit value ΔIa.

  FIG. 4B shows the deviation amount ΔI when the output amount is excessive. In the figure, the limit value ΔIc is a value at which the discharge amount does not change even if the operation current value is increased, for example. Actually, this value changes according to the operation current value required when the fuel injection device is normal, but here, the minimum value of the value that is assumed that the discharge amount does not change easily. Is the limit value ΔIc. Further, the excessive amount second time Δtc is the longest time for the deviation amount ΔI to reach the limit value ΔIc when the output amount is excessive.

  FIG. 4C shows the amount of deviation ΔI when the entry amount is insufficient. As shown in the figure, in this case, the increase rate of the shift amount is smaller than that when the output amount is excessive. In the figure, the limit value ΔIb indicates that the force applied to the fuel pump 6 is increased when the operating current is further increased when it is difficult to suck the fuel by the fuel pump 6 due to clogging of the fuel filter 4 or the like. 6 is a value that may cause deterioration. This limit value also actually changes in accordance with the operation current value required when the fuel injection device is normal, but here, it is simply set to the minimum value that may cause the above. Further, the shortest time Δta when the amount of filling is insufficient is set to the shortest time when the deviation amount ΔI reaches the limit value ΔIb when the amount of filling is insufficient.

  Incidentally, the time Δta for the deviation amount ΔI to reach the limit value ΔIb when the amount of entry is insufficient is usually several hundred hours to several thousand hours (or tens of thousands of kilometers as the travel distance), whereas the deviation amount ΔI when the output amount is excessive. The time ΔIc that reaches the limit value ΔIc is several seconds or less. As described above, there is a very large difference between these two times Δta and Δtc, but in FIG. 4, these differences are shown in a reduced manner for convenience.

  According to the property shown in FIG. 4, it can be seen that it is possible to diagnose whether or not there are various abnormalities in the fuel injection device based on the time change of the deviation amount ΔI. Here, processing related to abnormality diagnosis based on the properties shown in FIG. 4 will be described.

  Here, first, a process for estimating an operation current value required for the fuel pump 6 having a central characteristic value by feedback control when the fuel injection device is normal (process for determining a reference value of the operation amount) will be described. . FIG. 5 shows a processing procedure for the above estimation. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processing, first, in step S20, the detected value of the fuel pressure by the fuel pressure sensor 20, the detected value of the fuel temperature by the fuel temperature sensor 22, the detected value of the rotational speed of the crankshaft 8 by the crank angle sensor 24, and the diesel engine. Read the total operating time of. Here, the total operation time of the diesel engine may be the total startup time of the ECU 30, but the total operation time may be roughly defined by the travel distance of the vehicle. The total operating time may be sequentially stored and updated in the nonvolatile memory 32. In this case, it is determined that there is an abnormality by the abnormality diagnosis, and the part at the abnormal part is repaired or replaced. After that, the stored value can be initialized using a service tool or the like that is a communication tool with the ECU 30. Further, when the total operating time is grasped by the travel distance of the vehicle, the travel distance at that time is stored in the nonvolatile memory 32 after the parts are repaired or replaced.

  In the subsequent step S22, the amount of leak fuel due to static leak and dynamic leak is calculated based on the value read in step S20. Here, both the static leak and the dynamic leak depend on the fuel pressure in the common rail 12. This is because the higher the fuel pressure, the greater the force that causes fuel to flow from the high pressure fuel passage 14 to the low pressure fuel passage 18. Further, the amount of static leak increases as the temperature of the fuel increases. This is because the higher the temperature of the fuel, the lower the viscosity of the fuel. Moreover, since the discharge amount per unit time increases as the rotational speed increases, the leak amount per unit time due to static leak increases. Furthermore, if the total operating time is increased, the amount of leakage may increase to some extent due to aging (deterioration) of the fuel injection valve 16. In step S22, in view of this point, the amount of leaked fuel is calculated.

  In the subsequent step S24, the command injection amount for the fuel injection valve 16 is read. Here, the command injection amount is a command value for the amount of fuel injected through the fuel injection valve 16.

  In the subsequent step S26, when the target fuel pressure changes, the fuel amount is required to cause the actual fuel pressure to follow the target fuel pressure by the processing shown in FIG. For example, the change amount ΔPC of the target fuel pressure, the sum V of the volume of the fuel passage between the fuel pump 6 and the common rail 12 and the volume of the common rail 12, and the bulk modulus E of the fuel are used. It may be calculated as “ΔPC × V / E”.

  In the subsequent step S28, the operation current value is estimated based on the leaked fuel amount calculated in step S22, the command injection amount read in step S24, and the fuel amount calculated in step S26. That is, if the fuel injection device has no abnormality such as insufficient input amount or excessive output amount, the operation current value by the feedback control shown in FIG. 2 is the sum of the fuel amounts in steps S22 to S26. It is considered that the value becomes the discharge amount. For this reason, the operation current value for using this amount of fuel as the discharge amount is calculated as an estimated value of the operation current value.

  Note that when the process of step S28 is completed, this series of processes is temporarily terminated.

  Next, FIG. 6 shows a procedure of processing relating to the abnormality diagnosis. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processes, first, in step S30, the counter value n is incremented. Incidentally, the initial value of the counter value n is “0”. In the subsequent step S32, a deviation amount ΔIn of the actual operation amount by the feedback control shown in FIG. 2 is calculated with respect to the estimated value of the operation amount calculated in step 28 of FIG. Further, the time tn at this time is calculated. This time tn is basically calculated by adding the time elapsed from the previous process to the current process to the previous time. However, immediately after the start, the time corresponding to the processing cycle of FIG. 6 is added to the previous time.

  In the subsequent step S34, the change rate ΔI / Δt is calculated by averaging the change rate of the shift amount from the start of the processing related to the abnormality diagnosis, and the shift amount ΔI is calculated by averaging the shift amount. To do. Here, the averaging process is performed when the operation current value by the feedback control shown in FIG. 2 is read or when the change speed ΔI / Δt or the deviation is caused by noise being mixed in the process of FIG. This is to prevent a decrease in the reliability of the calculated value of the amount ΔI.

  In a succeeding step S36, it is determined whether or not the deviation amount ΔI is equal to or larger than a limit value ΔIb at the time of insufficient entry amount. Then, if it is determined that the deviation amount ΔI is equal to or greater than the limit value ΔIb when the amount is insufficient, the process proceeds to step S38.

  The processes in steps S38 to S42 are processes for determining whether the change speed ΔI / Δt is a speed corresponding to when the input amount is insufficient, a speed corresponding to when the output amount is insufficient, or neither. That is, when the change speed ΔI / Δt is less than the first speed ΔIb / Δtb when the output is excessive (step S38: NO) and is not less than the minimum speed ΔIa / Δta when the input is insufficient (step S40: YES) The process proceeds to step S44 because it is determined that there is an insufficient amount of entry. Further, when the change speed ΔI / Δt is equal to or higher than the first speed ΔIb / Δtb when the output is excessive (step S38: YES) and is equal to or higher than the second speed ΔIc / Δtc when the output is excessive (step S42: YES). Therefore, the process proceeds to step S46 because it is an excessive output abnormality.

  Here, the first speed ΔIb / Δtb when the output amount is excessive is equivalent to the speed until the deviation amount ΔI reaches the limit value ΔIb when the output amount is excessive. Further, the minimum speed ΔIa / Δta at the time of insufficient entry amount is the lowest speed assumed as the speed of the deviation amount at the time of insufficient entry amount. Further, the second speed ΔIc / Δtc when the output amount is excessive is equivalent to the speed until the deviation amount ΔI reaches the limit value ΔIc when the output amount is excessive.

  In step S44, it is determined that there is an inadequate amount of entry, and that effect is displayed on the display 28. Furthermore, the intake amount per unit time of the fuel pump 6 is limited. For example, when the fuel filter 4 is clogged, the negative pressure generated in the fuel pump 6 when the fuel pump 6 tries to suck the fuel increases. That is, since a larger force is applied to the fuel pump 6 than normal, the amount of suction per unit time is limited in order to suppress the force applied to the fuel pump 6. In practice, this is performed as a restriction on the operation current value (a restriction on the command discharge amount) or a restriction on the rotational speed of the crankshaft 8. Here, the rotational speed is limited because the fuel pump 6 is an engine-driven pump, and therefore, the suction amount per unit time increases as the rotational speed increases.

  On the other hand, in step S46, it is determined that the output amount is excessively abnormal, and that effect is displayed on the display 28.

  Further, when it is determined in step S36 that the deviation amount ΔI is less than the limit value ΔIb, or when it is determined in step S40 that the change speed ΔI / Δt is less than the minimum speed ΔIa / Δta at the time of insufficient entry, step When it is determined in S42 that the change speed ΔI / Δt is less than the second speed ΔIc / Δtc when the output is excessive, the process proceeds to step S48. In step S48, the deviation amount ΔIn calculated in step S32 and the time tn are stored in the nonvolatile memory 32.

  When the processes in steps S44, S46, and S48 are completed, this series of processes is temporarily ended.

  Incidentally, after the processes in steps S44 and S46, the shift amount Δti and the time ti stored in the nonvolatile memory 32 are initialized. However, if all the deviation amount Δti stored in the nonvolatile memory 32 in step S48 and the time ti are stored and held, the storage area of the nonvolatile memory 32 may be compressed. Is desirable. That is, in step 48, in addition to the deviation amount ΔIn calculated in step S32 and the time tn, the change speed ΔI / Δt calculated in step S34 and the deviation amount ΔI are stored. In addition, this process is an overwriting process for the value stored in the previous process of step S38. In step S34, the change rate is calculated as “{(previous change rate) × (n−1) + (current change rate)} / n” and the deviation amount is {(previous deviation amount). X (n-1) + (current deviation amount)} / n ".

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

  (1) The presence or absence of abnormality of the fuel injection device was diagnosed based on the temporal change of the deviation amount ΔI between the actual operation current value of the fuel pump 6 and the estimated operation current value by the feedback control shown in FIG. . Thereby, it is possible to appropriately diagnose what kind of abnormality is present in the fuel injection device.

  (2) By paying attention to the property that the change pattern of the deviation amount ΔI differs between when the input amount is insufficient and when the output amount is excessive, the presence / absence of the input amount insufficient abnormality and the excessive amount abnormality is diagnosed. Thereby, it is possible to appropriately diagnose the presence or absence of an inadequate input amount abnormality or an excessive output amount abnormality.

  (3) The operation current value was estimated based on the rotational speed of the crankshaft 8, the total operating time of the diesel engine, the temperature of the fuel in the fuel pump 6, and the fuel pressure in the common rail 12. Thereby, even if the operating current value of the fuel pump 6 when there is no abnormality in the fuel injection device changes due to the increase in the amount of leaked fuel due to the change in these parameters, the operating current value that reflects this change is changed. Can be estimated.

  (4) The intake amount per unit time of the fuel pump 6 was limited when it was determined that there was an abnormality in the inflow amount. Thereby, it is possible to prevent the fuel pump 6 from being applied with a larger force than normal due to an insufficient amount of entry.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 7 shows an abnormality diagnosis processing procedure according to this embodiment. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processing, first, in step S52, the shift amount ΔI and the time t are calculated as in step S32 of FIG. In a succeeding step S54, it is determined whether or not the deviation amount ΔI is not less than a limit value ΔIa. If it is determined that the value is greater than or equal to the limit value ΔIa, it is determined whether or not the initial time ta when the deviation amount exceeds the limit value ΔIa has been stored. If it is determined that it has not been stored, the initial time ta is set to the time t calculated in step S52 in step S58.

  On the other hand, when it is determined in step S56 that the initial time ta has been stored, or when the process of step S58 is completed, the process proceeds to step S60. In step S60, it is determined whether or not the deviation amount ΔI is greater than or equal to a limit value ΔIb. And when it is judged that it is more than limit value (DELTA) Ib, it transfers to step S62. In step S62, an elapsed time Δt from the initial time ta to the present is calculated.

  In subsequent steps S64 to S70, whether or not the elapsed time Δt until the deviation exceeds the limit value ΔIb is equivalent to the time when the deviation exceeds the limit value ΔIb when the amount of entry is insufficient, and the deviation is equal to the limit value ΔIc. It is determined whether or not the elapsed time Δt until exceeding is equivalent to the time when the deviation amount exceeds the limit value ΔIc when the output amount is excessive. That is, when the elapsed time Δt is equal to or longer than the first time Δtb when the amount is excessive (step S64: YES) and is equal to or longer than the shortest time Δa when the amount is insufficient (step S66: YES), Control goes to step S72. Further, the elapsed time Δt is less than the first time when the amount of discharge is excessive (step S64: NO), the deviation amount ΔI is equal to or greater than the limit value ΔIc (step S68: YES), and the elapsed time Δt is the amount of discharge. If it is less than the second time at the time of overload (step S70: YES), it is determined that the output amount is insufficient, and the process proceeds to step S74.

  In step S72, the same process as in step S44 of FIG. 6 is performed. In step S74, the same process as in step S46 of FIG. 6 is performed.

  Also by the second embodiment described above, the effects (1) to (4) of the first embodiment can be obtained.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In each of the above embodiments, when the operation current value is estimated, all of the rotational speed, the total operating time, the fuel temperature, and the fuel pressure are considered, but even if only at least one of these is taken into consideration, it is not considered at all. The operation current value can be estimated with high accuracy. Also, instead of taking these into consideration when calculating the estimated value, the diagnostic accuracy can be improved by variably setting the diagnostic criteria according to at least one of these parameters. Further, the effects (1), (2), and (4) of the first embodiment can be obtained without considering these at all.

  In each of the above embodiments, the amount of inhalation per unit time is limited when the amount of filling is insufficient, but even if this is not performed, the effects (1) to (3) of the previous first embodiment can be achieved. Can get.

  The reference value to be compared with the actual operation current value is not limited to a value that is set each time based on the amount of fuel flowing out from the common rail 12. For example, if the diagnosis is performed only in a specific operation state, the reference value may be a fixed value set in advance.

  In each of the above-described embodiments, the diagnosis process was performed assuming the patterns shown in FIGS. 3 and 4 in advance when the fuel injection device is normal and abnormal, but as these patterns, FIGS. It is not restricted to what was illustrated to. In short, what is necessary is just to diagnose the presence or absence of various abnormalities in the fuel injection device based on the change over time in the difference between the operation current value and the reference value.

  The internal combustion engine is not limited to a diesel engine, and may be, for example, a cylinder injection gasoline engine.

The figure which shows the whole structure of the engine system in 1st Embodiment. The flowchart which shows the procedure of the feedback control of the fuel pressure in the embodiment. The figure which shows the relationship between the discharge amount requested | required at the time of feedback control, and the operation electric current value. The time chart which shows the transition example of the operation current value by feedback control. The flowchart which shows the procedure of the process concerning estimation of the operation current value in the said embodiment. 6 is a flowchart showing a processing procedure for abnormality diagnosis according to the embodiment. The flowchart which shows the process sequence of the abnormality diagnosis concerning 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 4 ... Fuel filter, 6 ... Fuel pump, 10 ... Fuel metering valve, 12 ... Common rail, 16 ... Fuel injection valve, 30 ... ECU.

Claims (6)

A fuel injection device comprising: a pressure accumulating chamber for storing fuel in a high pressure state; a fuel pump for pressurizing fuel in the pressure accumulating chamber; and a fuel injection valve for injecting fuel stored in the pressure accumulating chamber in a high pressure state. In the fuel injection device abnormality diagnosis device for diagnosing the presence or absence of abnormality,
Control means for feedback-controlling the fuel pressure in the accumulator chamber to a target fuel pressure by operating the fuel pump;
Setting means for variably setting a reference value, which is an operation amount of the fuel pump assumed when there is no abnormality in the fuel injection device, based on an amount of fuel flowing out of the pressure accumulating chamber ;
Diagnostic means for diagnosing the presence or absence of an inadequate entry amount in which the discharge amount of the fuel pump is reduced instead of the operation amount based on the increasing speed of the difference between the actual operation amount by the control means and the reference value An abnormality diagnosis device for a fuel injection device. In addition to an abnormality in the shortage of the amount of fuel pump discharged in place of the manipulated variable, the diagnostic means has an abnormality in the amount of fuel flowing out of the fuel path from the fuel pump to the fuel injection valve. Has the function of diagnosing the presence or absence of excessive output
2. The increasing speed at the time of diagnosing that there is an abnormality in the excessive amount of output is set to be larger than the increasing speed at the time of diagnosing that there is an abnormality in insufficient amount of filling. An abnormality diagnosis device for a fuel injection device. A fuel injection device comprising: a pressure accumulating chamber for storing fuel in a high pressure state; a fuel pump for pressurizing fuel in the pressure accumulating chamber; and a fuel injection valve for injecting fuel stored in the pressure accumulating chamber in a high pressure state. In the fuel injection device abnormality diagnosis device for diagnosing the presence or absence of abnormality,
Control means for feedback-controlling the fuel pressure in the accumulator chamber to a target fuel pressure by operating the fuel pump;
Setting means for variably setting a reference value, which is an operation amount of the fuel pump assumed when there is no abnormality in the fuel injection device, based on an amount of fuel flowing out of the pressure accumulating chamber ;
Diagnosing means for diagnosing the presence or absence of abnormality of the fuel injection device based on a time change of a difference between an actual operation amount by the control means and the reference value;
The diagnosis means performs the diagnosis by comparing a time variation of a difference between the actual operation amount and the reference value and a predetermined pattern,
In the pattern, there is an abnormality in the amount of fuel flowing out from the fuel path between the fuel pump and the fuel injection valve, and the pattern assumed when the fuel pump discharge amount decreases instead of the operation amount. A fuel injection device comprising a pattern assumed when an excessive amount of fuel is generated, and the pattern when the amount of excessive fuel is set is set so that the speed of the time change is larger than that when the amount of fluid is insufficient Abnormality diagnosis device.   The setting means estimates a leaked fuel amount that leaks through the fuel injection valve, and sets the reference value based on a sum of the estimated leaked fuel amount and a fuel amount injected through the fuel injection valve. The abnormality diagnosis device for a fuel injection device according to any one of claims 1 to 3, wherein the abnormality diagnosis device is set each time.   5. The apparatus according to claim 1, further comprising fail-safe means for restricting a fuel intake amount per unit time by the fuel pump when it is determined by the diagnostic means that the shortage has occurred. The abnormality diagnosis device for a fuel injection device according to claim 1. The setting means, the rotational speed of the mounted by an internal combustion engine of the fuel injection system, the total operating time of the internal combustion engine, according to at least one of the fuel pressure in the temperature and the pressure accumulation chamber of the fuel in the fuel pump, the 6. The abnormality diagnosis device for a fuel injection device according to claim 1, wherein the reference value is variably set .

Images