JP2018040290A - Fuel injection control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device of an engine which can further exactly detect the generation of an abnormality causing the excess and deficiency of engine torque.SOLUTION: An energization control part 27 of a fuel injection control device 20 of a diesel engine 10 sets the timing and a time of the energization of an injector 13 on the basis of a required injection amount QFIN which is calculated by a requirement injection amount calculation part 26. A monitor injection amount calculation part 29 acquires the timing and a time of the energization, and calculates a monitor injection amount QM so that the monitor injection amount reaches an actual injection amount when the energization timing of the injector 13 is earlier than the start timing of a partial combustion determination period being a period of a regulation in an expansion stroke, and becomes larger than "0" and smaller than the actual injection amount when the energization timing is within the partial combustion determination period. A diagnosis part 30 compares the sum of the monitor injection amount QM of each energization performed in one cycle of a cylinder 11 with the requirement injection amount QFIN, and diagnoses the presence or absence of an abnormality of the fuel injection control device 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine fuel injection control device.

  A fuel injection control device such as an on-board diesel engine calculates a fuel injection amount required for generating a required engine torque as a required injection amount, and sets an injector energization time according to the required injection amount. The fuel injection control is performed so that the engine torque as required is generated. If an abnormality occurs in such a fuel injection control device and the injector is not properly energized, the engine torque will be excessive or insufficient.

  Conventionally, in the fuel injection control device for an engine described in Patent Document 1, the energization time of the injector is acquired, the amount of fuel actually injected from the injector (actual injection amount) is calculated from the energization time, and the actual injection is performed. By comparing the amount and the required injection amount, the presence or absence of abnormality of the fuel injection control device is diagnosed.

JP 2013-238203 A

  If all of the injected fuel burns and contributes to the generation of engine torque, the fuel injection amount remains the index value for engine torque. The coincidence between the required injection amount and the actual injection amount at this time means that the engine torque is generated as required, and the required engine torque is generated even by the above-described conventional diagnostic method of the fuel injection control device. You can check whether or not.

  However, when fuel injection is performed in the latter half of the expansion stroke, a portion of the injected fuel becomes unburned and does not contribute to the generation of engine torque. Will no longer be required. For this reason, the coincidence between the required injection amount and the actual injection amount at this time does not necessarily mean that the engine torque is generated as required, and the above-described conventional fuel injection control device diagnosis method generates the engine torque as required. You will not be able to confirm whether you are doing.

  The present invention has been made in view of such circumstances, and the problem to be solved is to provide an engine fuel injection control device that can more accurately detect the occurrence of an abnormality that causes excessive or insufficient engine torque. There is to do.

  The fuel injection control device for an engine that solves the above problem is applied to an engine that includes an injector that injects fuel while energization is performed. The fuel injection control device includes a required injection amount calculation unit that calculates a required injection amount, which is a fuel injection amount necessary for generating the required engine torque, and the required engine torque based on the required injection amount. An energization control unit that sets the timing and time of energization of the injector so as to inject fuel so as to be generated.

  In such a fuel injection control device, the amount of fuel actually injected from the injector (actual injection amount) can be obtained from the time of energization of the injector in accordance with the energization. If all of the injected fuel burns and contributes to the generation of engine torque, the generation amount of engine torque can be uniquely determined from the actual injection amount. However, when fuel is injected in the latter half of the expansion stroke, part of the injected fuel becomes unburned and does not contribute to generation of engine torque. Therefore, when fuel injection may be performed at such time, the amount of fuel that actually contributes to the generation of engine torque is smaller than the actual injection amount.

  Here, whether or not the fuel is injected during the period in which the amount of fuel contributing to the generation of the engine torque as described above is smaller than the actual injection amount can be confirmed from the time when the injector is energized. That is, in a period in which the amount of fuel contributing to the generation of engine torque is less than the actual injection amount depending on whether or not the timing of energization of the injector is within a specified period (partial combustion determination period) during the expansion stroke. It can be checked whether fuel has been injected.

  On the other hand, in the fuel injection control device, when the injector is energized, the timing and time of the energization are acquired and a monitor injection amount that is an evaluation value of the fuel injection amount for diagnosis is calculated. A monitor injection amount calculation unit is provided. When the energization timing is earlier than the start of the partial combustion determination period, which is a specified period during the expansion stroke, the monitor injection amount calculation unit is an amount of fuel actually injected from the injector in response to energization. The monitor injection amount is calculated so as to be the same amount as the injection amount. On the other hand, when the energization timing is within the partial combustion determination period, the monitor injection amount is calculated so as to be larger than “0” and smaller than the actual injection amount. According to such a monitor injection amount calculation unit, when the time of energization of the injector is in the partial combustion determination period, the amount that reflects the fact that the amount of fuel that contributes to the generation of engine torque is less than the actual injection amount The monitor injection amount is calculated. The fuel injection control device includes a diagnosis unit that compares the total of the monitor injection amounts of the energizations performed in one cycle of the cylinder with the required injection amount to diagnose whether or not the fuel injection control device is abnormal. ing. Thus, if the diagnosis is performed using the monitor injection amount as described above, even if the fuel is injected at a time when the amount of fuel contributing to the generation of the engine torque is smaller than the actual injection amount, the engine torque as required is obtained. It will be possible to check whether or not this has occurred. Therefore, according to the engine fuel injection control device, it is possible to more accurately detect the occurrence of an abnormality that causes excessive or insufficient engine torque.

  Even during the period in which the amount of fuel contributing to the generation of engine torque is smaller than the actual injection amount, the amount of unburned fuel increases as the injector energization period is delayed. Therefore, the monitor injection amount calculation unit in the fuel injection control apparatus monitors the actual injection amount as the energization timing is closer to the end timing of the partial combustion determination period when the energization timing is within the partial combustion determination period. It is desirable to calculate the monitor injection amount so that the ratio of the injection amount becomes small. Such calculation of the monitor injection amount can be performed as follows, for example. That is, either the start timing or the end timing of energization to the injector is used as the energization timing. When the energization timing is before the start timing of the partial combustion determination period, the value is “1”, and the energization timing is The torque sensitivity coefficient is such that the value becomes smaller as it is retarded during the partial combustion determination period, and the value becomes “0” when the same energization timing is after the end timing of the partial combustion determination period. Set the value according to the same energization period. Then, the monitor injection amount is calculated so as to be a product obtained by multiplying the actual injection amount by the torque sensitivity coefficient.

  Note that, when performing split injection including fuel injection performed during the partial combustion determination period, part of the fuel injected during the partial combustion determination period contributes to the generation of engine torque. If fuel injection is performed ignoring the engine torque generated by fuel injection in such a partial combustion determination period, engine torque larger than the required amount is generated. Even in such a case, when the energization control unit in the fuel injection control device performs split injection including fuel injection performed during the partial combustion determination period, fuel is injected at a time earlier than the start timing of the partial combustion determination period. The energization timing and time are set so that the total amount of fuel is less than the required injection amount, and the amount of fuel injection performed during the partial combustion determination period is added to the total to be larger than the required injection amount. By doing so, it becomes possible to set the fuel injection amount of each of the divided injections in consideration of the engine torque generated by the fuel injection in the partial combustion determination period.

The block diagram which shows typically the structure of one Embodiment of the fuel injection control apparatus of an engine. The time chart which shows an example of the embodiment of the fuel injection by the fuel-injection control apparatus of the embodiment. The flowchart of the monitor injection amount calculation process which the monitor injection amount calculating part implements in the fuel injection control apparatus of the embodiment. The graph which shows the relationship between the torque sensitivity coefficient used for the calculation of the monitor injection quantity in the monitor injection quantity calculation process, and an energization start time. The flowchart of the diagnostic process which a diagnostic part implements in the fuel-injection control apparatus of the embodiment.

Hereinafter, an embodiment of an engine fuel injection control device will be described in detail with reference to FIGS.
As shown in FIG. 1, a piston 12 and an injector 13 are respectively provided in a cylinder 11 of a diesel engine 10 to which the fuel injection control device 20 of the present embodiment is applied. The injector 13 injects fuel into the cylinder 11 while energization is performed.

  In the cylinder 11, combustion is repeated with four strokes of an intake stroke, a compression stroke, an expansion (combustion) stroke, and an exhaust stroke as one cycle. In the intake stroke, air is taken into the cylinder 11 as the piston 12 descends. During the compression stroke, the air taken in the cylinder 11 is compressed as the piston 12 rises. In the expansion stroke, the fuel injected from the injector 13 is self-ignited in the compressed air, and the piston 12 is lowered by the combustion pressure of the fuel. In the exhaust stroke, exhaust gas generated by combustion is exhausted from the cylinder 11 as the piston 12 rises.

  The piston 12 is connected to a crankshaft 15 that is an output shaft of the diesel engine 10 via a connecting rod 14. Then, the crankshaft 15 rotates in accordance with the elevation of the piston 12 in the cylinder 11.

  A crank position sensor 21, an accelerator position sensor 22, and an injection pressure sensor 23 are connected to the fuel injection control device 20 of the present embodiment that performs fuel injection control of the diesel engine 10. The crank position sensor 21 outputs a pulse wave signal (crank signal) to the fuel injection control device 20 according to the rotation of the crankshaft 15. Further, the accelerator position sensor 22 outputs a signal corresponding to the accelerator pedal depression amount (accelerator pedal depression amount ACCP) to the fuel injection control device 20. Further, the injection pressure sensor 23 outputs a signal corresponding to the fuel pressure (injection pressure PM) injected by the injector 13 into the cylinder 11 to the fuel injection control device 20.

  The fuel injection control device 20 is provided with a signal processing unit 24 and a timer 25. The signal processing unit 24 calculates and outputs the following values from the output signals of the sensors (21 to 23). That is, the signal processing unit 24 calculates and outputs the engine speed NE and the crank angle θ from the output signal of the crank position sensor 21. The signal processing unit 24 calculates and outputs the accelerator pedal depression amount ACCP from the output signal of the accelerator position sensor 22 and the injection pressure PM from the output signal of the injection pressure sensor 23. Further, the timer 25 outputs a signal representing the current time.

  Further, the fuel injection control device 20 includes a required injection amount calculation unit 26, an energization control unit 27, and a drive circuit 28 as a control structure related to control of fuel injection of the injector 13. The required injection amount calculation unit 26 calculates a required injection amount QFIN, which is a fuel injection amount necessary for generating the required engine torque, and outputs it to the energization control unit 27. The energization control unit 27 generates an injection command signal SINJ that is a signal for instructing the timing and time of energization of the injector 13 based on the required injection amount QFIN, and outputs it to the drive circuit 28. The drive circuit 28 energizes the injector 13 in response to the injection command signal SINJ. In addition, the drive circuit 28 generates an energization monitor signal SMN that is a signal representing the energization state of the injector 13 and outputs the energization monitor signal SMN to the monitor injection amount calculation unit 29 described later.

  In addition, the fuel injection control device 20 diagnoses the presence or absence of its own abnormality. The fuel injection control device 20 includes the monitor injection amount calculation unit 29 and the diagnosis unit 30 as a control structure for such diagnosis. The monitor injection amount calculation unit 29 calculates a monitor injection amount QM that is an evaluation value of the fuel injection amount for diagnosis based on the energization monitor signal SMN input from the drive circuit 28 and outputs the calculated value to the diagnosis unit 30. The diagnosis unit 30 compares the total of the monitored injection amounts QM of each energization performed in one cycle of the cylinder 11 (total monitored injection amount QMT) with the required injection amount QFIN calculated by the required injection amount calculation unit 26. Thus, the presence or absence of abnormality of the fuel injection control device 20 is diagnosed.

  The fuel injection control device 20 is provided with a fail safe processing unit 31. The fail-safe processing unit 31 performs a process for fail-safe when the diagnosis unit 30 diagnoses that there is an abnormality. As the fail-safe process at the time of abnormality, for example, a process of limiting the fuel injection amount to be equal to or less than the minimum necessary amount for evacuation traveling is performed.

(Fuel injection control)
Next, details of the fuel injection control of the injector 13 by the above-described required injection amount calculation unit 26, energization control unit 27, and drive circuit 28 will be described. It should be noted that the timing of energization and fuel injection of the injector 13 in the following description is such that the crank angle θ when the piston 12 in the cylinder 11 is located at the compression top dead center (TDC) is “0 ° CA” and the compression top dead. This is expressed by the rotation angle of the crankshaft 15 in the advance direction (BTDC) and the retard direction (ATDC) with respect to the crank angle θ of the point.

  The required injection amount calculation unit 26 calculates the fuel injection amount per cycle necessary for generating the engine torque corresponding to the required torque with respect to the required torque obtained from the engine speed NE and the accelerator pedal depression amount ACCP. Calculated as the base injection amount. The required injection amount calculation unit 26 performs various corrections on the base injection amount to calculate the required injection amount QFIN. The calculation of the required injection amount QFIN by the required injection amount calculation unit 26 is set to a fuel injection amount necessary for generating the required torque when it is assumed that the entire amount of injected fuel is burned. Done.

  In the fuel injection control device 20 of the present embodiment, split injection is performed in which fuel for the required injection amount QFIN is injected in multiple batches. In such split injection, pilot injection, after injection, pre-post injection, and post injection are performed in addition to main injection that is main fuel injection. Pilot injection is fuel injection performed before main injection in order to improve the ignitability of the fuel injected by main injection. The after injection is a fuel injection that is performed immediately after the main injection in order to burn out the remaining fuel. The post-injection is a fuel injection that is performed after combustion in the cylinder 11 is completed in order to supply unburned fuel to the catalyst. Further, the pre / post injection is a fuel injection performed in the latter half of the expansion stroke in order to raise the exhaust gas temperature or supply CO generated by incomplete combustion of the fuel to the catalyst. In pilot injection, main injection, and after injection, almost all of the injected fuel is burned and contributes to the generation of engine torque. However, post injection performed after the end of combustion does not contribute to the generation of engine torque. It is a jet. On the other hand, in the pre-post injection, only a part of the injected fuel burns and contributes to the generation of engine torque.

  The number of main injections in one cycle is determined to be one, but the number of other injections is changed according to the operating condition of the diesel engine 10. Specifically, the number of pilot injections is between 0 and 3, the number of after injections is between 0 and 2, the number of pre / post injections is between 0 and 2, and the number of post injections. Is changed between 0 and 1 time.

  In the fuel injection control device 20 of the present embodiment that performs such split injection, the energization control unit 27 generates an injection command signal in the following manner. First, the energization control unit 27 calculates the injection amount of each injection other than the main injection based on the current operation state of the diesel engine 10 (engine speed NE, accelerator pedal depression amount ACCP, etc.). In addition, the energization control unit 27 calculates the start timing of each injection including the main injection based on the current operation state of the diesel engine 10. Then, the energization control unit 27 calculates the injection amount of the main injection (main injection amount) so as to satisfy the following equation based on each calculated injection amount and the required injection amount QFIN calculated by the required injection amount calculation unit 26. QMAIN) is calculated. In the equation, QPLT1, QPLT2, and QPLT3 represent the injection amounts of the pilot injections, QAF1 and QAF2 represent the injection amounts of the after injections, and QPPST1 and QPPST2 represent the injection amounts of the respective pre-post injections. ing. MQT1 and MQT2 represent torque efficiency coefficients of the respective pre / post injections. The values of the torque efficiency coefficients MQT1 and MQT2 are set according to the start timing of each pre-post injection, and the values contribute to the generation of engine torque by burning out of the fuel injected in the pre-post injection. It represents the ratio of the amount of fuel to be used. Specifically, the values of the torque efficiency coefficients MQT1 and MQT2 are set to smaller values as the start timing of the corresponding pre-post injection is later in a range larger than “0” and smaller than “1”.

As described above, the energization control unit 27 determines the injection amount of each injection reflecting that a part of the fuel injected by the pre-post injection contributes to the generation of the engine torque. That is, the energization control unit 27 allocates the fuel for the required injection amount QFIN to each post-injection, main injection, and after-injection, and a part of the pre-post injection amount. The injection amount is determined. Therefore, when pre / post injection is performed, the total injection amount of pilot injection, main injection, and after injection becomes smaller than the required injection amount QFIN. In this case, the total of the injection amounts of pilot injection, main injection, after injection, and pre / post injection is larger than the required injection amount QFIN.

  Furthermore, the energization control unit 27 calculates the energization time of the injector 13 necessary for the fuel injection of each calculated injection amount based on the injection pressure PM. Since the fuel injection rate (fuel injection amount per unit time) of the injector 13 increases as the injection pressure PM is higher, the energization control unit 27 is the same when the injection pressure PM is high even if the injection amount is the same. The injection time is calculated so that the time is shorter than when the injection pressure PM is low. Then, the energization control unit 27 generates an injection command signal and outputs it to the drive circuit 28 so that the energization control unit 27 is turned on when the start time of each injection is reached and then turned off when the injection time has elapsed.

  FIG. 2 shows an example of the state of fuel injection in this embodiment. The figure shows the situation when the number of injections is maximum, that is, in addition to the main injection, three post injections, two after injections, two pre-post injections, and one post injection. The transition of the injection command signal, the injection rate of the injector 13 and the energization monitor signal when the operation is performed is shown. The drive circuit 28 energizes the injector 13 while the injection command signal is on. In response to this, fuel is injected from the injector 13. In addition, the drive circuit 28 generates an energization monitor signal SMN as a pulse wave signal that falls when the energization of the injector 13 starts and rises when the energization ends. This is output to the quantity calculation unit 29.

  The monitoring period shown in the figure indicates the reference period of the energization monitor signal SMN when the monitor injection amount calculation unit 29 and the diagnosis unit 30 diagnose the abnormality of the fuel injection control device 20, and from the pilot injection to the post injection. It is set so as to include all the injection periods of each injection up to. Also, during the period from “θ1” to “θ2” shown in the figure, when the injector 13 is energized during that period, a part of the fuel injected in response to the energization is obtained. A period during which combustion is unburned (hereinafter referred to as a partial combustion determination period) is shown. That is, the above-described pre-post injection is fuel injection that is performed by energization within such a partial combustion determination period.

(Abnormal diagnosis)
Next, details of the abnormality diagnosis of the fuel injection control device 20 by the above-described monitor injection amount calculation unit 29 and the diagnosis unit 30 will be described. As described above, in the abnormality diagnosis, the monitor injection amount calculation unit 29 calculates the monitor injection amount QM every time the injector 13 is energized based on the energization monitor signal SMN, and the diagnosis unit 30 performs one cycle of the cylinder 11. The fuel injection control device 20 is diagnosed for an abnormality by comparing the total of the monitored injection amounts QM (total monitored injection amount QMT) of each energization performed and the required injection amount QFIN.

  FIG. 3 shows a flowchart of the monitor injection amount calculation process performed by the monitor injection amount calculation unit 29. The monitor injection amount calculation unit 29 repeatedly executes this process while the diesel engine 10 is in operation.

  When this processing is started, first, in step S100, it is determined whether or not the falling of the pulse of the energization monitor signal SMN is detected. Note that the falling of the pulse of the energization monitor signal SMN indicates that the energization of the injector 13 has started. If such a falling edge of the pulse is detected (YES), the process proceeds to step S110. If not detected (NO), the process proceeds to step S120. When the process proceeds to step S110, the current time acquired from the timer 25 is set as the energization start time TS, and the current crank angle calculated by the signal processing unit 24 is set as the energization start timing θS. After being stored, the current process is terminated.

  On the other hand, when the process proceeds to step S120, it is determined in step S120 whether or not the rising of the pulse of the energization monitor signal SMN is detected. Note that the rise of the pulse of the energization monitor signal SMN indicates that the energization of the injector 13 is terminated. Here, when such a rising edge of the pulse is detected (YES), the process proceeds to step S130, and when it is not detected (NO), the current process is terminated.

  When the process proceeds to step S130, the elapsed time from the energization start time TS to the current time based on the energization start time TS stored in step S110 and the current time acquired from the timer 25 in step S130. The energization time T is calculated as follows. Such energization time T represents the energization time of the injector 13.

  Subsequently, in step S140, the injection pressure PM calculated by the signal processing unit 24 from the output signal of the injection pressure sensor 23 is read. In the next step S150, based on the energization time T and the injection pressure PM, the actual injection amount of the injector 13 at the same energization time T estimated from the energization time T and the injection pressure PM is calculated as the actual injection amount Q. Is done.

  Further, in the subsequent step S160, the torque sensitivity coefficient κ is calculated from the energization start timing θS stored in step S110. FIG. 4 shows the relationship between the value of the torque sensitivity coefficient κ set in step S160 and the energization start timing θS. As shown in the figure, the value of the torque sensitivity coefficient κ is “1” when the energization start timing θS is before the start timing θ1 of the partial combustion determination period, and when the energization start timing θS is within the partial combustion determination period. The energization start timing θS is set to be smaller as it is retarded, and the energization start timing θS is set to “0” in the range after the end timing θ2 of the partial combustion determination period. The value of the torque sensitivity coefficient κ is a value corresponding to the ratio of the amount of fuel that burns and contributes to the generation of engine torque among the fuel injected from the injector 13 during the energization time T.

  In the subsequent step S170, the monitor injection amount QM is calculated so as to be a product obtained by multiplying the actual injection amount Q by the torque sensitivity coefficient κ (QM = κ × Q). The calculated monitor injection amount QM is equal to the actual injection amount Q when the energization start timing θS is earlier than the start timing θ1 of the partial combustion determination period. The monitor injection amount QM is larger than “0” and smaller than the actual injection amount Q when the energization start timing θS is in the period from the start timing θ1 to the end timing θ2 of the partial combustion determination period. It becomes. Furthermore, when the energization start timing θS is later than the end timing θ2 of the partial combustion determination period, the monitor injection amount QM is “0” regardless of the actual injection amount Q.

  When the monitor injection amount QM is calculated, the calculated monitor injection amount QM is output to the diagnosis unit 30 in the subsequent step S180. In step S190, the energization start time TS, the energization start timing θS, and the monitor injection amount QM are cleared, and the current process is terminated.

FIG. 5 shows a flowchart of the diagnostic process performed by the diagnostic unit 30. The diagnosis unit 30 repeatedly performs this process during operation of the diesel engine 10.
When this process is started, first, in step S200, it is determined whether or not it is during the monitoring period. If it is during the monitoring period (YES), the process proceeds to step S210. If not (NO), the process proceeds to step S230.

  When the process proceeds to step S210, it is determined in step S210 whether or not the monitor injection amount QM is input from the monitor injection amount calculation unit 29. If the monitor injection amount QM has been input (YES), the process proceeds to step S220. If not input (NO), the current process is terminated. When the process proceeds to step S220, in step S220, the updated monitor injection amount QMT is updated so that the updated value is the sum of the currently input monitor injection amount QM added to the pre-update value. After the value is updated, the current process is terminated.

  On the other hand, when the process proceeds to step S230, it is determined in step S230 whether it is the end of the monitoring period. The determination here is performed during the monitoring period when the diagnosis process is executed last time, and when it is not during the monitoring period as the end of the monitoring period. If it is at the end of the monitoring period (YES), the process proceeds to step S240. If it is not at the end of the monitoring period (NO), the current process is terminated.

  When the process proceeds to step S240, in step S240, it is determined whether or not the total monitor injection amount QMT exceeds the sum of the required injection amount QFIN and the specified value α (QMT> QFIN + α).

  If a negative determination is made in step S240, that is, if “QMT ≦ QFIN + α” (NO), the process proceeds to step S250, and the value of the temporary abnormality counter C is cleared to “0” in step S250. The In step S260, after the value of the total monitor injection amount QMT is cleared to “0”, the current process is terminated.

  On the other hand, if an affirmative determination is made in step S240, that is, if “QMT> QFIN + α” (YES), the process proceeds to step S270, and the value of the temporary abnormality counter C is incremented by “1” in step S270. Is done. Then, in the following step S280, it is determined whether or not the value of the temporary abnormality counter C is equal to or greater than a specified abnormality determination value.

  If the value of the temporary abnormality counter C is less than the prescribed abnormality determination value (S280: NO), the process proceeds to step S260. In step S260, the value of the total monitor injection amount QMT is “0”. After being cleared, the current process is terminated.

  On the other hand, if the value of the temporary abnormality counter C is equal to or greater than the prescribed abnormality determination value (S280: YES), the process proceeds to step S290, and an abnormality signal is output to the failsafe processing unit 31 in step S290. Is called. Thereafter, in step S260, the value of the total monitor injection amount QMT is cleared to “0”, and then the current process is terminated.

  In such a diagnosis process, the determination in step S240 is performed every time the monitoring period ends, that is, every cycle of the cylinder 11. The value of the temporary abnormality counter C is incremented when an affirmative determination is made in step S240, and is cleared when a negative determination is made. Therefore, the value of the temporary abnormality counter C represents an affirmative determination in step S240, that is, the duration (number of cycles) in which “QMT> QFIN + α”. In step S280 of the diagnosis process, when the value of the temporary abnormality counter C is equal to or greater than the abnormality determination value, an abnormality signal is output from the failsafe processing unit 31. That is, in the above-described diagnosis process, when the state of “QMT> QFIN + α” continues for a specified period or longer, it is diagnosed that there is an abnormality in the fuel injection control device 20.

  The value of the total monitor injection amount QMT when used for the determination in step S250 in such a diagnosis process is the sum of the respective monitor injection amounts QM input from the monitor injection amount calculation unit 29 during the monitoring period. That is, in step S250, the sum of the monitored injection amounts QM of the energizations performed in one cycle of the cylinder 11 is compared with the required injection amount QFIN to diagnose the presence or absence of abnormality in the fuel injection control device 20.

  In the above, the description has been given focusing on one of the cylinders 11 provided in the diesel engine 10, but in actuality, the following processes (a) to (d) are individually performed for each cylinder 11. It is to be done.

(A) Generation and output of the injection command signal SINJ by the energization control unit 27.
(B) Energization of the injector 13 by the drive circuit 28 and generation and output of the energization monitor signal SMN.

(C) Monitor injection amount calculation unit 29 calculates and outputs monitor injection amount QM.
(D) Diagnosis by calculation of the total monitor injection amount QMT by the diagnosis unit 30 and comparison between the total monitor injection amount QMT and the required injection amount QFIN.

(Function and effect)
Then, the effect | action and effect of the fuel-injection control apparatus 20 of this embodiment comprised as mentioned above are demonstrated.

  In the fuel injection control device 20 of the present embodiment, the energization control unit 27 energizes the injector 13 so as to perform split injection including pre-post injection in which fuel is injected by energizing the injector 13 during the partial combustion determination period. Control is in progress. In such pre-post injection, only a part of the injected fuel burns and contributes to the generation of engine torque. Therefore, the energization control unit 27 also considers the amount of engine torque generated in such pre- and post-injection, and generates the same amount of engine torque as the amount generated by combustion of fuel for the required injection amount QFIN. The injection amount of each injection in the divided injection is set. In such a case, the total amount of post-injection, main injection, and after-injection in which injection is performed earlier than the start timing θ1 of the partial combustion determination period is smaller than the required injection amount QFIN, The sum of the injection amounts of the injections is larger than the required injection amount QFIN.

  On the other hand, the energization time T of the injector 13 in each injection is known from the energization monitor signal SMN, and the actual injection amount Q of the injector 13 in each injection is obtained from the energization time T and the injection pressure PM. However, in this case, since the total injection amount of each injection does not match the required injection amount QFIN, the fuel injection is normally performed only by comparing the total actual injection amount Q of each injection with the required injection amount QFIN. As a result, it becomes impossible to detect the generation of engine torque exceeding the demand.

  On the other hand, the monitor injection amount calculation unit 29 in the present embodiment acquires the energization time (energization time T) of the injector 13 and the energization time (energization start timing θS) from the energization monitor signal SMN. Monitor injection quantity QM is calculated. The monitor injection amount QM is equal to the actual injection amount Q when the energization start timing θS is earlier than the start timing θ1 of the partial combustion determination period, and the energization start timing θS is within the partial combustion determination period (from the start timing θ1). In the case of the period until the end timing θ2, the calculation is performed so that the amount is larger than “0” and smaller than the actual injection amount Q. The monitor injection amount QM is calculated to be “0” regardless of the actual injection amount Q when the energization start timing θS is later than the end timing θ2 of the partial combustion determination period. Therefore, the monitor injection amount QM is calculated as an amount corresponding to the amount of fuel that contributes to the generation of engine torque in the injected fuel.

  In this embodiment, the diagnosis unit 30 compares the total monitor injection amount QMT, which is the sum of the monitor injection amounts QM of the energizations performed in one cycle of the cylinder 11, with the required injection amount QFIN, and the fuel injection control device. 20 abnormalities are diagnosed. The required injection amount QFIN is calculated as a fuel injection amount necessary to generate a required amount of torque when it is assumed that the injected fuel is burned in its entirety. On the other hand, the total monitor injection amount QMT corresponds to the sum of the amounts of fuel that burns and contributes to the generation of engine torque out of the fuel injected in each injection. Therefore, it can be confirmed whether the engine torque according to the request | requirement has generate | occur | produced appropriately by the said comparison.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the abnormality of the fuel injection control device 20 that causes the generation of engine torque exceeding the requirement is diagnosed. However, from the comparison between the total monitor injection amount QMT and the requested injection amount QFIN, a request is made. It is also possible to perform an abnormality diagnosis of the fuel injection control device 20 that causes the generation of an engine torque that is less than. For example, if step S240 in the abnormality diagnosis process of FIG. 5 is a process for determining whether or not “QMT <QFIN−β (β is a specified constant)”, generation of an excessively small engine torque that is less than the required value. The presence or absence of an abnormality in the inviting fuel injection control device 20 can be diagnosed. Further, if the step S240 is determined to be an affirmative determination in the case of “QMT> QFIN + α” or “QMT <QFIN−β”, an abnormality that causes generation of an excessively small engine torque below the request, an excessive value exceeding the request. It is possible to diagnose both of the abnormalities that cause the generation of a large engine torque.

  The following abnormality of the fuel injection control device 20 can be diagnosed from the comparison between the total monitor injection amount QMT and the required injection amount QFIN as described above. When the energization timing of the injector 13 for after-injection is delayed and enters the partial combustion determination period, only a part of the fuel injected as the after-injection of the soot after which all of the injected fuel is originally burned is burned. Therefore, the amount of engine torque generated is less than required. In such a case, the after-injection monitor injection amount QM is calculated to be smaller than the actual injection amount Q, and the total monitor injection amount QMT is smaller than the required injection amount QFIN. Therefore, the presence or absence of abnormality of the fuel injection control device 20 that causes a delay in the energization timing of the injector 13 for after injection can be diagnosed by comparing the total monitor injection amount QMT and the required injection amount QFIN.

  The following abnormality of the fuel injection control device 20 can be further diagnosed from the comparison between the total monitor injection amount QMT and the required injection amount QFIN as described above. When the energization timing of the injector 13 for post-injection is advanced and enters the partial combustion determination period, part of the fuel injected as post-injection of soot that is not originally combusted is burned, so that engine torque is generated. The amount will be more than required. In such a case, according to the monitor injection amount calculation unit 29, the post injection monitor injection amount QM is calculated to be an amount larger than “0”. As a result, the total monitor injection amount QMT is calculated from the required injection amount QFIN. Will also increase. Therefore, the presence or absence of an abnormality in the fuel injection control device 20 that leads to early energization timing of the injector 13 for post injection can be diagnosed by comparing the total monitor injection amount QMT and the required injection amount QFIN.

  In the above embodiment, the energization start timing θS is obtained from the energization monitor signal SMN and the monitor injection amount QM is calculated. However, the energization end timing is obtained from the energization monitor signal SMN, and the energization When the end timing is within the partial combustion period, the monitor injection amount QM may be calculated so as to be larger than “0” and smaller than the actual injection amount Q.

  In the above embodiment, the value of the torque sensitivity coefficient κ during the partial combustion determination period is set so as to gradually decrease with respect to the change in the energization timing to the retard side. The value of the torque sensitivity coefficient κ in the partial combustion determination period may be a constant larger than “0” and smaller than “1”. Even in such a case, the monitored injection amount QM when energization is performed during the partial combustion determination period is larger than “0” and smaller than the actual injection amount Q, and the amount of fuel that contributes to the generation of engine torque. The amount is calculated as an amount reflecting that the amount is smaller than the actual injection amount Q.

  In the above embodiment, when the energization timing of the injector 13 is later than the end timing θ2 of the partial combustion determination period, the monitor injection amount QM is calculated so that the value becomes “0” regardless of the actual injection amount Q. However, when the energization timing of the injector 13 is later than the end timing θ2, the calculation of the monitor injection amount QM for the energization may not be performed in the first place.

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine (engine), 11 ... Cylinder, 13 ... Injector, 20 ... Fuel injection control apparatus, 26 ... Request injection amount calculating part, 27 ... Current supply control part, 29 ... Monitor injection amount calculating part, 30 ... Diagnosis part.

Claims (4)

A fuel injection control device for an engine comprising an injector for injecting fuel into a cylinder while energization is performed,
A required injection amount calculation unit that calculates a required injection amount that is a fuel injection amount necessary for generating the required engine torque;
An energization control unit configured to set the timing and time of energization of the injector so as to perform fuel injection based on the requested injection amount so as to generate the engine torque corresponding to the requested amount;
When energization of the injector is performed, the timing and time of the energization are acquired, and when the energization timing is earlier than the start of the partial combustion determination period, which is a specified period during the expansion stroke, If the current injection amount is the same as the actual injection amount that is the amount of fuel actually injected from the injector in response to energization, and the energization timing is within the partial combustion determination period, it is greater than “0”, and A monitor injection amount calculation unit that calculates a monitor injection amount that is an evaluation value of the diagnostic fuel injection amount so that the amount is smaller than the actual injection amount;
A diagnostic unit for diagnosing whether or not there is an abnormality in the fuel injection control device by comparing the sum of the monitored injection amounts of the energizations performed in one cycle of the cylinder and the required injection amount;
An engine fuel injection control device comprising: The monitor injection amount calculation unit, when the energization timing is within the partial combustion determination period, the monitor injection amount with respect to the actual injection amount is closer to the end timing of the partial combustion determination period. The engine fuel injection control device according to claim 1, wherein the monitor injection amount is calculated such that the ratio of the engine is small. The monitor injection amount calculation unit uses either a start timing or an end timing of energization of the injector as the energization timing, and the energization timing is before the start timing of the partial combustion determination period. Sometimes the value is “1”, and when the same energization timing is within the same partial combustion determination period, the value becomes smaller as it is retarded, and when the same energization time is after the end timing of the partial combustion determination period The value of the torque sensitivity coefficient is set according to the same energization time so that the value becomes “0”, and the monitor injection amount is calculated so as to be a product obtained by multiplying the actual injection amount by the torque sensitivity coefficient. The engine fuel injection control device according to claim 2. The energization control unit, when performing split injection including fuel injection performed in the partial combustion determination period, the total amount of fuel injected at a timing earlier than the start timing of the partial combustion determination period is the required injection The energization timing and time are set such that the amount obtained by adding the fuel injection amount of the fuel injection performed during the partial combustion determination period to the total is larger than the required injection amount. Item 4. The fuel injection control device for an engine according to any one of Items 1 to 3.