JP4497045B2 - Fuel injection control device - Google Patents

Description

  The present invention operates a fuel injection device that includes a pressure accumulation chamber that stores fuel in a high pressure state, a fuel pump that pressurizes and supplies fuel to the pressure accumulation chamber, and a fuel injection valve that injects fuel stored in the pressure accumulation chamber. The present invention relates to a fuel injection control device that performs fuel injection control.

  As this type of fuel injection device, one having a common pressure accumulation chamber (common rail) for supplying high-pressure fuel to a fuel injection valve of each cylinder of a diesel engine is well known. The fuel injection control device in this common rail type diesel engine sets a command injection period when operating the fuel injection valve based on the required fuel amount and the fuel pressure in the common rail.

  However, since the fuel pressure in the common rail fluctuates due to the pressurized supply (pumping) of fuel from the fuel pump, the same injection period is determined depending on whether the fuel pumping period from the fuel pump overlaps with the fuel injection period. Even if it is set, the amount of fuel actually injected varies.

  Therefore, conventionally, as seen in Patent Document 1 below, for calculating the fuel injection period between the cylinder in which the fuel pumping period by the fuel pump and the fuel injection period by the fuel injection valve overlap and the cylinder that does not overlap, Control devices using different maps have also been proposed. Thereby, an appropriate fuel injection period can be set according to the presence or absence of an overlapping period.

  By the way, in the actual fuel injection device, each characteristic such as the amount of leaked fuel that leaks without being injected from the fuel injection valve into the combustion chamber of the diesel engine and the discharge characteristic of the fuel pump is caused by individual differences and changes over time. There is variation. For this reason, in the control device, the fuel pumping mode (presence / absence of pumping or the like) of the fuel pump at the time of fuel injection changes due to this variation, and the actual injection amount may deviate from the required injection amount. Further, the amount of leaked fuel and the pumping characteristic can be changed by the difference in fuel characteristics such as viscosity coefficient. For this reason, in the above control device, the actual fuel injection amount is reduced from the required fuel injection amount by changing the fuel pumping mode (whether pumping or not) by the fuel pump at the time of fuel injection due to the difference in fuel characteristics. There is also a risk of deviation.

In addition, as a fuel injection control device, there are also those described in Patent Documents 2 and 3 below, for example, in addition to those described in Patent Document 1.
JP 2003-222046 A JP-A-8-144826 JP 2005-127164 A

  The present invention has been made in order to solve the above-described problems, and the object of the present invention is when the fuel pumping mode by the fuel pump changes during fuel injection due to individual differences in fuel injection devices or changes over time. However, an object of the present invention is to provide a fuel injection control device that can perform fuel injection control with high accuracy.

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

A first aspect of the present invention is a fuel comprising a pressure accumulating chamber that stores fuel in a high pressure state, a fuel pump that pressurizes and supplies fuel to the pressure accumulating chamber, and a fuel injection valve that injects fuel stored in the pressure accumulating chamber. In a fuel injection control device that performs fuel injection control by operating an injection device, means for capturing a detection result of a detection means for detecting a fuel pressure in the pressure accumulating chamber, and a required injection amount that is a required value for the fuel injection amount And an operation amount setting means for setting an operation amount of the fuel injection valve based on the detected fuel pressure, an operation means for operating the fuel injection valve based on an operation amount set by the operation amount setting means, A correction amount for correcting the operation amount is calculated based on a difference between the behavior of the fuel pressure detected when the fuel injection valve is operated according to the operation amount and a reference behavior, and the operation unit performs the next time An operation amount of the time later operation a correcting means for correcting, based on the correction amount, the fuel pump, to perform and suction and pressurized supply of the fuel by the reciprocating motion of the plungers comprises a plurality of plungers The correction means is close to the correction amount calculated based on the difference between the behavior of the fuel pressure detected when the fuel injection valve is operated and the reference behavior, and the timing of the operation. The correction amount specific to each plunger related to the pressure supply is calculated by associating with the plunger related to the pressure supply at the timing .

In the above configuration, the behavior of the fuel pressure in the pressure accumulating chamber when the fuel injection valve is operated depends on the fuel pumping mode from the fuel pump to the pressure accumulating chamber during this time (presence of pumping, etc.). This pumping mode varies depending on the pumping characteristics of the fuel pump, the amount of leaked fuel that leaks without being injected from the fuel injection valve, and the like. For this reason, based on the difference between the detected behavior of the fuel pressure and the reference behavior, it is possible to grasp the fluctuation of the fuel pumping mode. In view of this, in the configuration described above, the correction amount of the operation amount is calculated based on the difference. For this reason, according to the above configuration, the fuel injection can be appropriately performed even in a pumping mode different from the pumping mode assumed when calculating the operation amount of the fuel injection valve (the behavior of the fuel pressure coincides with the reference behavior at this time). The valve can be operated, and as a result, fuel injection control can be performed with high accuracy.
In particular, in the above configuration, the pumping characteristics may be different for each plunger due to individual differences and changes over time. If the pumping characteristics are different for each plunger, the mode of pumping fuel to the pressure accumulating chamber when the fuel injection valve is operated will vary. In this regard, in the above configuration, the correction amount is associated with the plunger involved in the fuel pumping when calculating the correction amount, so that the injection amount variation due to the variation in the pumping mode caused by the variation in the pumping characteristics of the plunger is preferable. Can be suppressed.
The invention according to claim 2 is a fuel comprising a pressure accumulating chamber for storing fuel in a high pressure state, a fuel pump for pressurizing and supplying fuel to the pressure accumulating chamber, and a fuel injection valve for injecting fuel stored in the pressure accumulating chamber. In a fuel injection control device that performs fuel injection control by operating an injection device, means for capturing a detection result of a detection means for detecting a fuel pressure in the pressure accumulating chamber, and a required injection amount that is a required value for the fuel injection amount And an operation amount setting means for setting an operation amount of the fuel injection valve based on the detected fuel pressure, an operation means for operating the fuel injection valve based on an operation amount set by the operation amount setting means, A correction amount for correcting the operation amount is calculated based on a difference between the behavior of the fuel pressure detected when the fuel injection valve is operated according to the operation amount and a reference behavior, and the operation unit performs the next time Correction means for correcting the operation amount at the time of descending operation based on the correction amount, the correction means for each of the three parameters of the fuel injection start timing, the fuel pressure and the injection period at the timing. It is characterized in that a correction amount specific to each parameter value is calculated.
In the above configuration, the behavior of the fuel pressure in the pressure accumulating chamber when the fuel injection valve is operated depends on the fuel pumping mode from the fuel pump to the pressure accumulating chamber during this time (presence of pumping, etc.). This pumping mode varies depending on the pumping characteristics of the fuel pump, the amount of leaked fuel that leaks without being injected from the fuel injection valve, and the like. For this reason, based on the difference between the detected behavior of the fuel pressure and the reference behavior, it is possible to grasp the fluctuation of the fuel pumping mode. In view of this, in the configuration described above, the correction amount of the operation amount is calculated based on the difference. For this reason, according to the above configuration, the fuel injection can be appropriately performed even in a pumping mode different from the pumping mode assumed when calculating the operation amount of the fuel injection valve (the behavior of the fuel pressure coincides with the reference behavior at this time). The valve can be operated, and as a result, fuel injection control can be performed with high accuracy.
In particular, in the above configuration, if the injection start timing and the injection period are different, the fuel pressure mode in the injection period varies. In order to grasp the pumping mode based on the behavior of the fuel pressure, it is desirable to refer to the initial value of the fuel pressure, that is, the fuel pressure at the above timing. In this regard, in the above configuration, the operation amount can be corrected with the correction amount suitable for the situation by calculating the correction amount for each of these three parameters.
According to a third aspect of the present invention, there is provided a fuel comprising a pressure accumulating chamber for storing fuel in a high pressure state, a fuel pump for pressurizing and supplying the fuel to the pressure accumulating chamber, and a fuel injection valve for injecting fuel stored in the pressure accumulating chamber. In a fuel injection control device that performs fuel injection control by operating an injection device, means for capturing a detection result of a detection means for detecting a fuel pressure in the pressure accumulating chamber, and a required injection amount that is a required value for the fuel injection amount And an operation amount setting means for setting an operation amount of the fuel injection valve based on the detected fuel pressure, an operation means for operating the fuel injection valve based on an operation amount set by the operation amount setting means, A correction amount for correcting the operation amount is calculated based on a difference between the behavior of the fuel pressure detected when the fuel injection valve is operated according to the operation amount and a reference behavior, and the operation unit performs the next time Correction means for correcting an operation amount at the time of descending operation based on the correction amount, and the correction means starts supply of fuel from the fuel pump based on an amount of fuel supplied from the fuel pump to the pressure accumulating chamber. Supply start timing calculation means for calculating timing, and reference value calculation means for calculating the reference behavior based on fuel injection start timing, the required injection amount, the supply start timing, and the supply amount Features.
In the above configuration, the behavior of the fuel pressure in the pressure accumulating chamber when the fuel injection valve is operated depends on the fuel pumping mode from the fuel pump to the pressure accumulating chamber during this time (presence of pumping, etc.). This pumping mode varies depending on the pumping characteristics of the fuel pump, the amount of leaked fuel that leaks without being injected from the fuel injection valve, and the like. For this reason, based on the difference between the detected behavior of the fuel pressure and the reference behavior, it is possible to grasp the fluctuation of the fuel pumping mode. In view of this, in the configuration described above, the correction amount of the operation amount is calculated based on the difference. For this reason, according to the above configuration, the fuel injection can be appropriately performed even in a pumping mode different from the pumping mode assumed when calculating the operation amount of the fuel injection valve (the behavior of the fuel pressure coincides with the reference behavior at this time). The valve can be operated, and as a result, fuel injection control can be performed with high accuracy.
In particular, in the above configuration, the behavior of the fuel pressure when the fuel injection valve is operated is determined by the injection start timing, the required injection amount, the supply start timing, and the supply amount if there are no individual differences in fuel injection devices and changes over time. . In this regard, according to the above configuration, the behavior that serves as a reference can be appropriately calculated.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the fuel injection device includes a plurality of fuel injection valves, and each of the fuel injection valves includes the correction means. A correction amount unique to each fuel injection valve is calculated based on the difference between the behavior of the fuel pressure detected when operated and the behavior serving as the reference.

  In the above configuration, the amount of leaked fuel that leaks without being injected from each fuel injection valve depends on the clearance between the body of each fuel injection valve and the displacement member inside the fuel injection valve. For this reason, the fuel leakage amount of each fuel injection valve may vary. If the amount of leaked fuel varies, when the control is performed to compensate for this, the pumping mode during the injection period may change due to the change in the pumping amount by the fuel pump. In this regard, in the above configuration, by calculating a unique correction amount for each fuel injection valve, fluctuations in the injection amount due to fluctuations in the pumping mode caused by individual differences in the fuel injection valves can be suitably suppressed.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the correction means uses a fuel pressure detected at the end of fuel injection as a fuel pressure used for calculating the correction amount. It is used as a behavior.

  In the above configuration, the correction amount is calculated based on the fuel pressure detected at the end of injection. The fuel pressure at the end of the injection changes according to the fuel pumping mode to the pressure accumulating chamber during the fuel injection period. For this reason, the difference between the pumping mode assumed in the reference fuel pressure and the actual pumping mode can be grasped by comparing the fuel pressure at the end of injection with the reference fuel pressure. In view of this point, in the above configuration, the correction amount commensurate with the actual pumping mode can be calculated based on the difference between the fuel pressure at the end of injection and the reference fuel pressure.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the correction means includes a differential pressure between a fuel pressure detected at the start of fuel injection and a fuel pressure detected at the end of the injection, and the reference. The correction amount is calculated on the basis of a difference from a reference differential pressure as a behavior.

  In the above configuration, the pumping mode cannot be uniquely grasped depending on the fuel pressure at the end of injection. In this regard, in the above configuration, the correction amount that appropriately reflects the variation in the fuel pumping mode to the pressure accumulating chamber during the fuel injection period is obtained by using the differential pressure between the fuel pressure at the start of injection and the fuel pressure at the end of injection. Can be calculated.

(First embodiment)
Hereinafter, a first embodiment in which a fuel injection control device according to the present invention is applied to a fuel injection control device of 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 an intake metering valve 10, and the amount of fuel discharged to the outside is determined by operating the intake metering valve 10. Further, the fuel pump 6 includes two plungers, and these plungers reciprocate between a top dead center and a 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 common rail 12 stores the fuel pumped from the fuel pump 6 in a high pressure state and supplies the fuel 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 various sensors that detect the operating state and operating environment of the diesel engine, such as a fuel pressure sensor 20 that detects the fuel pressure in the common rail 12 and a crank angle sensor 22 that detects the rotation angle of the crankshaft 8. Yes. Further, the engine system includes an accelerator sensor 24 that detects an operation amount of an accelerator pedal operated in response to a user's acceleration request.

  On the other hand, the electronic control unit (ECU 30) is composed mainly of a microcomputer, takes in the detection results of the various sensors, and controls the output of the diesel engine based on this.

  The ECU 30 performs fuel injection control so as to appropriately control the output of the diesel engine. 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.

  Here, the fuel injection control according to the present embodiment will be further described with reference to FIG.

  FIG. 2 (a) shows the transition of the fuel intake and discharge (pressure feed) mode by one plunger (first plunger), and FIG. 2 (b) shows the fuel intake and discharge by the other plunger (second plunger). The transition of the (pumping) mode is shown respectively. Further, FIGS. 2C to 2F show fuel injection command periods (command injection periods) for the fuel injection valves 16 of the first cylinder to the fourth cylinder, respectively.

  As shown in the drawing, the amount of suction is determined by the operation mode of the suction metering valve 10 when the first plunger and the second plunger are displaced toward the bottom dead center. Then, when the first plunger or the second plunger is displaced toward the top dead center next time, the fuel sucked last time is discharged.

  In the present embodiment, the fuel is injected through the fuel injection valve 16 of the first cylinder or the second cylinder corresponding to the time when the fuel is pumped from the first plunger to the common rail 12. Further, the fuel is injected through the fuel injection valve 16 of the third cylinder or the fourth cylinder corresponding to the time when the fuel is pumped from the second plunger to the common rail 12. As described above, in this embodiment, the fuel supply timing to the common rail 12 by the fuel pump 6 and the fuel injection timing through the fuel injection valve 16 are in one-to-one correspondence (in synchronization with each other). )

  In the present embodiment, the fuel injection timing is further set so that the command injection period and the fuel pumping period from the fuel pump 6 do not overlap. For this reason, the operation amount of the fuel injection valve 16 is set on the assumption that fuel is not pumped from the fuel pump 6 to the common rail 12 during the command injection period. Here, since the actual injection amount is determined according to the fuel pressure in the common rail 12 and the command injection period, even if the command injection period is the same, the actual injection amount differs depending on whether the command injection period and the pumping period are overlapped. However, if the condition that there is no overlap between the command injection period and the pumping period is satisfied, the actual injection amount can be accurately controlled by the fuel pressure detected at the predetermined timing and the command injection period.

  However, actually, the fuel injection valves 16 of the respective cylinders may have different amounts of leaked fuel that cause fuel to leak to the fuel tank 2 side via the low-pressure fuel passage 18 due to these individual differences. In addition, the amount of leaked fuel may change due to changes in the fuel injection valve 16 over time. Further, in the fuel pump 6, since there is an individual difference in the clearance between the body and the plunger, the fuel discharge characteristics may be different between the first plunger and the second plunger. Further, the discharge characteristics may change due to the change of the fuel pump 6 over time. In addition, if the viscosity coefficient varies depending on the nature of the fuel in the fuel tank 2, the amount of leaked fuel, the discharge characteristics, and the like change. When such a change occurs, control is performed to increase the amount of fuel pumped to compensate for this change by feedback control that causes the detected fuel pressure to follow the target fuel pressure. As a result, there is a concern that the command injection period and the pumping period overlap.

  FIG. 3 shows a transition example of the fuel pressure in the common rail 12 when there is no overlap between the command injection period and the pumping period. Specifically, FIG. 3 (a) shows the command injection period in any one of the cylinders, FIG. 3 (b) shows the transition of the fuel pressure in the common rail 12, and FIG. 3 (c) shows the pressure feed in any of the plungers. The transition of an aspect is shown.

  In FIG. 3B, the transition of the fuel pressure when the command injection period and the fuel pumping period do not overlap is shown by a solid line. On the other hand, an example in which the command injection period and the pumping period overlap due to an increase in the pumping amount and a longer pumping period is shown by a one-dot chain line in FIG. And the transition of the fuel pressure at this time is shown by a one-dot chain line in FIG.

  As shown in the drawing, the transition of the fuel pressure in the common rail 12 during the command injection period differs depending on whether the command injection period and the pumping period overlap. For example, the differential pressure ΔPs of the fuel pressure between the start timing and the end timing of the command injection period when the command injection period and the pumping period do not overlap is larger than the differential pressure ΔPr when they overlap. For this reason, even if the command injection period is the same, the actual injection amount is different.

  Therefore, in the present embodiment, the actual injection amount is accurately controlled to the required injection amount by the processing shown in FIG. The process shown in FIG. 4 is repeatedly executed by the ECU 30 for each cylinder, for example, at a predetermined cycle.

  In this series of processes, first, in step S10, the fuel pressure Ps detected by the fuel pressure sensor 20 is sampled (taken in) immediately before the start timing (injection start timing) of the command injection period. In the following step S12, a command injection period TQ is calculated based on the fuel pressure Ps and the command injection amount. Here, the command injection amount is a required injection amount calculated based on the accelerator pedal operation amount detected by the accelerator sensor 24 and the rotation angle of the crankshaft 8 detected by the crank angle sensor 22. Further, the command injection period TQ is for the purpose of actually injecting the command injection amount of fuel when the command injection period and the pumping period do not overlap and the fuel pressure at the start timing of the command injection period is the fuel pressure Ps. It is an appropriate command injection period TQ. The calculation of the command injection period TQ is performed based on a predetermined map, for example.

  In the subsequent step S14, it is determined whether or not the three parameters of the command injection period TQ, the fuel pressure Ps, and the injection start timing T have been equivalent to the values in the current fuel injection. Here, when the process shown in FIG. 4 is performed for the first time, a negative determination is made in step S14, and the process proceeds to step S18.

  In step S18, fuel is injected from the fuel injection valve 16 by operating the fuel injection valve 16. When the process in step S18 is performed following the negative determination in step S14, the fuel injection valve 16 is operated during the command injection period TQ calculated in step S12.

  In the subsequent step S20, the fuel pressure Pf detected by the fuel pressure sensor 20 is sampled (taken in) at the end timing (injection end timing) of the command injection period TQ. Further, in step S22, a differential pressure ΔPr between the fuel pressure Ps at the injection start timing and the fuel pressure Pf at the injection end timing is calculated.

  In the subsequent step S24, it is determined whether or not the absolute value of the difference between the calculated differential pressure ΔPr and the reference differential pressure ΔPs is greater than or equal to a predetermined value A. Here, the reference differential pressure ΔPs is the difference in fuel pressure between the injection start timing and the injection end timing under the condition that the command injection period and the pumping period do not overlap as shown in FIG. It is a value assumed as a pressure. Specifically, the ECU 30 includes a three-dimensional map shown in FIG. 5 that defines the relationship between the three parameters of the fuel pressure Ps at the injection start timing, the command injection period TQ, and the injection start timing T and the reference differential pressure ΔPs. The reference differential pressure ΔPs is calculated according to the values of these three parameters. Therefore, when the absolute value of the difference between the calculated differential pressure ΔPr and the reference differential pressure ΔPs is the predetermined value A, the command injection period and the fuel pumping period overlap, and depending on the command injection period TQ, It is considered that the actual injection amount is greatly different from the command injection amount.

  For this reason, if it is determined in step S24 that the value is equal to or greater than the predetermined value A, the differential pressure ΔPr (correction amount for correcting the command injection period TQ) calculated in step S22 is stored in step S26. Specifically, this differential pressure ΔPr is stored for each of the three parameters of the fuel pressure Ps, the command injection period TQ, and the injection start timing T as shown in FIG. That is, the process shown in step S26 is a process of storing a unique value for each of these three parameters. Further, in the present embodiment, these differential pressures ΔPr are stored for each cylinder. As a result, each differential pressure ΔPr calculated in step S26 reflects the individual difference or temporal change of any one of the fuel injection valves 16, and further the individual difference or temporal change of any one plunger of the fuel pump 6. Can be made. When the process of step S26 is completed, the series of processes shown in FIG.

  On the other hand, when it is determined in step S14 that the three parameters of the command injection period TQ, the fuel pressure Ps, and the injection start timing T correspond to the values in the current fuel injection before, the process proceeds to step S16. . In step S16, the fuel pressure Ps sampled in step S10 is corrected by the following equation.

Psn = Ps + m (ΔPs−ΔPr)
Here, the proportionality coefficient m is used. In the above equation, the reference differential pressure ΔPs is assumed when the above three parameters in the map shown in FIG. 5 correspond to the values in the current fuel injection. Further, the differential pressure ΔPr is assumed to be obtained when the above three parameters are equivalent to the values in the current fuel injection among those shown in FIG. The above equation “m (ΔPs−ΔPr)” is for calculating an appropriate command injection period TQ using a process for calculating the command injection period TQ under the condition that the command injection period TQ and the pumping period do not overlap. This is a fuel pressure correction value for calculating the apparent fuel pressure. That is, as shown in FIG. 3, when the command injection period TQ and the pumping period do not overlap, the degree of decrease in the fuel pressure in the common rail 12 becomes larger than when they overlap. On the other hand, if the command injection period TQ is constant, the fuel amount actually injected increases as the fuel pressure in the common rail 12 increases. For this reason, in order to calculate the appropriate command injection period TQ by the process of calculating the command injection period TQ under the condition that the command injection period TQ and the pumping period actually overlap, but do not overlap Is preferably corrected so that the fuel pressure in the common rail 12 is higher than the actual fuel pressure Ps.

  The command injection period TQ is corrected using the apparent fuel pressure Psn thus calculated. The corrected command injection period TQ is shorter than that calculated in step S12. Then, when the command injection period TQ is corrected, the processes after step S18 described above are performed.

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

  (1) Based on the difference between the differential pressure ΔPf of the fuel pressure at the injection start timing and the injection end timing and the reference differential pressure ΔPs, the command injection period TQ when the fuel injection valve 16 is operated from the next time is corrected. As a result, the fuel injection valve 16 can be appropriately used even in a pumping mode different from the fuel pumping mode assumed when calculating the command injection period TQ (specifically, the pumping period and the command injection period TQ do not overlap). Thus, fuel injection control can be performed with high accuracy.

  (2) The command injection period TQ is corrected for each cylinder based on the difference between the differential pressure ΔPf detected for each cylinder and the reference differential pressure ΔPs. Thus, a unique correction amount can be calculated for each fuel injection valve 16. As a result, the fuel injection amount varies due to individual differences in the fuel injection valves 16, and the actual injection amount varies due to variations in the degree of decrease in the fuel pressure in the common rail 12. Can be suitably suppressed.

  In addition, this causes the plunger involved in the pressure feeding to be associated with the fuel injection valve 16 at a timing close to the operation timing of the fuel injection valve 16, so that the variation in the pressure feeding mode due to the variation in the discharge characteristics of the plunger. Variations in the actual injection amount can also be suitably suppressed.

  (3) The command injection period TQ is corrected separately for each value of the three parameters of the fuel injection start timing, the fuel pressure at the timing, and the injection period. As a result, the command injection period TQ can be corrected with a correction amount suitable for the situation.

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

  In the present embodiment, fuel injection control is performed so that the command injection period TQ and the pumping period overlap. FIG. 7 shows a mode of fuel injection control according to the present embodiment. Specifically, FIG. 7 (a) shows the transition of the fuel intake and discharge (pressure feed) mode by one plunger (first plunger), and FIG. 7 (b) shows the fuel flow by the other plunger (second plunger). The transitions of the suction and discharge (pressure feed) modes are shown respectively. Further, FIGS. 7C to 7F show command injection periods for the fuel injection valves 16 of the first cylinder to the fourth cylinder, respectively.

  As shown in the figure, the period during which fuel is pumped from the first plunger to the common rail 12 and the command injection period of the fuel injection valve 16 of the first cylinder or the second cylinder overlap. Further, the period during which the fuel is pumped from the second plunger to the common rail 12 and the command injection period of the fuel injection valve 16 of the third cylinder or the fourth cylinder overlap.

  In the present embodiment, the command injection period is calculated on the assumption that the fuel pumping period and the command injection period overlap. Specifically, in step S12 of FIG. 4, the command injection amount and the fuel pressure are set under the condition that the crank angle (or cam angle) of the overlap period between the pumping period and the command injection period is in a predetermined region. A process for calculating an appropriate command injection period based on Ps is performed.

  However, even in this case, if the overlap mode between the pumping period and the command injection period varies, the command injection period TQ calculated in step S12 may not be an appropriate value. Therefore, also in this embodiment, the command injection amount is corrected based on the difference between the fuel pressure differential pressure ΔPf and the reference differential pressure ΔPs between the injection start timing and the injection end timing. This process is basically the same as that shown in FIG.

  However, the reference differential pressure ΔPs is a differential pressure assumed under the condition that the pumping period and the command injection period overlap in a predetermined crank angle region, and this value is the same as the map shown in FIG. Is stored in advance in the map. In addition, it is desirable that the proportionality coefficient m in step S16 in FIG. 4 is different from that in the first embodiment.

  According to the present embodiment described above in detail, the following effects can be obtained in addition to the effects according to the effects (1) to (3) of the first embodiment.

  (4) The fuel injection control is performed so as to overlap the pumping period and the command injection period, and the basic value of the command injection period is calculated under the condition that they overlap in a predetermined crank angle region. The fuel injection control based on the overlap between the pumping period and the command injection period is compared with the fuel injection control based on the non-overlap, and the control accuracy of the actual injection amount when the overlap mode varies. Is known to the inventors. For this reason, according to the present embodiment, the fuel injection control can be performed with higher accuracy.

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

  In the present embodiment, an overlap period between the command injection period and the pumping period is calculated based on the amount of fuel pumped by the fuel pump 6, the injection start timing, and the command injection period. And based on the calculated overlap period, the command injection period calculated based on the fuel pressure and the command injection amount is corrected. Thus, according to the present embodiment, by calculating the overlap period between the command injection period and the pumping period, the command injection amount is appropriate even when the injection start timing or the like changes according to the operating state. Can be obtained.

  However, when calculating the overlapping period of the command injection period and the pumping period in this way, it is assumed that this is a characteristic based on the discharge characteristic of the fuel pump 6 and the like. For this reason, for example, when the pumping start timing fluctuates even if the pumping amount is the same due to individual differences or changes with time of the fuel pump 6 and differences in the viscosity coefficient of the fuel used, etc. It cannot be calculated accurately.

  Therefore, in the present embodiment, basically, while performing the process of correcting the command injection period by calculating the overlapping period of the command injection period and the pumping period, the fluctuation of the actual pumping period and the like are considered to be the fuel pressure during fuel injection. Based on this behavior, the command injection period is further corrected based on the detection result. This will be described in further detail below.

  FIG. 8 shows a processing procedure for calculating the command injection period according to the present embodiment. This process is repeatedly executed by the ECU 30 for each cylinder, for example, at a predetermined cycle.

  In this series of processing, first, in step S30, the command injection amount is captured. In the subsequent step S32, the amount of leaked fuel leaking from the fuel injection valve 16 to the low pressure fuel passage 18 side based on the rotational speed detected by the crank angle sensor 22, the fuel pressure detected by the fuel pressure sensor 20, the command injection amount, and the like. Is calculated. In the subsequent step S34, the pumping amount of the fuel pump 6 determined by the feedback control is calculated (estimated) based on the command injection amount taken in in step S30 and the leaked fuel amount calculated in step S32. Here, since the fuel amount flowing out from the common rail 12 is compensated by the feedback control of the fuel pressure, it is considered that the pumping amount becomes the fuel amount flowing out. In view of the fact that the sum of the leak amount and the command injection amount flows out of the common rail 12, the outflow fuel amount is calculated as a pumping amount. At this time, when the target fuel pressure changes, it is desirable to further include a fuel amount that compensates for the difference between the actual fuel pressure and the target fuel pressure in the pumping amount.

  In the subsequent step S36, the fuel pressure start timing of the fuel pump 6 to the common rail 12 is calculated. In other words, since the fuel pump 6 is an engine-driven pump, the crank angle (or cam angle) at which the pumping is started is uniquely determined by the pumping amount if the individual differences of the fuel pump 6 and changes with time are ignored. Can do. This step S36 may be a process using a map that defines the relationship between the pumping amount and the pumping start timing, and geometric information about the stroke change of the plunger of the fuel pump 6 and the shape of the plunger, and the pumping. The pumping start timing may be calculated based on the amount.

  In the subsequent step S38, the injection start timing is captured. In step S40, a correction amount for the command injection period TQ is calculated based on the pumping start timing, the pumping amount, and the injection start timing. That is, the correction amount of the basic command injection period calculated based on the fuel pressure and the command injection amount is calculated based on the overlap period of the injection period and the pumping period grasped by the pumping start timing, the pumping amount, the injection start timing, etc. . In subsequent step S42, the basic injection period calculated based on the command injection amount and the fuel pressure is corrected by the correction amount calculated in step S40 and a learning value described later. Here, the basic injection period is calculated under the condition that the overlapping mode of the command injection period and the pumping period becomes a specific mode as in step S12 of FIG. Here, the command injection period and the pumping period may not be overlapped as in the first embodiment, and the command injection period and the pumping period are predetermined as in the second embodiment. It is good also as conditions that it overlaps in a mode.

  When the processing of step S42 is completed in this way, in step S44, fuel is injected from the fuel injection valve 16 by operating the fuel injection valve 16 based on the command injection period calculated in step S42.

  In subsequent step S46, a reference value of the fuel pressure at the injection end timing is calculated. Here, the fuel pressure in the common rail 12 decreases due to the fuel flowing out from the common rail 12 as the fuel is injected from the fuel injection valve 16, and the fuel pressure increases due to the fuel pump 6 sending the fuel from the fuel pump 6 to the common rail 12. Based on these two factors, the fuel pressure reference value at the injection end timing is calculated. This is calculated based on the injection start timing, the fuel pressure at the same timing, the command injection amount, the pumping start timing calculated in step S36, and the pumping amount.

  In the subsequent step S48, a learning value for compensating for the difference between the actual injection amount and the command injection amount is calculated based on the difference between the detected value of the fuel pressure at the injection end timing and the reference value calculated in step S48. . Here, the difference between the detected value of the fuel pressure at the injection end timing and the reference value calculated in step S48 is assumed in the process of step S40 regarding the discharge characteristics of the fuel pump 6, the viscosity coefficient of the fuel, and the like. The difference from the (central characteristic value) is quantified. Therefore, using this difference, it is possible to calculate a learning value that compensates for deviation of the actually injected fuel amount from the command injection amount due to variations in the discharge characteristics of the fuel pump 6. This learning value is used in step S42 from the next time.

  When the process of step S48 is completed, this series of processes is temporarily terminated.

  According to the present embodiment described above in detail, the following effects can be obtained in addition to the effects (1) to (3) of the first embodiment.

  (5) Before referring to the behavior of fuel pressure during fuel injection by predicting and calculating the overlap period between the command injection period and the pumping period prior to fuel injection and calculating the command injection period TQ based on this Therefore, the calculation accuracy of the command injection period TQ can be increased.

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

  In the first and second embodiments, the command injection period TQ is set for each plunger without correcting the command injection period TQ based on the fuel pressure Pf (or differential pressure ΔPf) at the injection end timing for each cylinder. If corrected, it is possible to compensate for variations in the injection amount due to variations in the discharge characteristics of the plungers.

  The start of fuel injection or the end of fuel injection is not limited to the start timing or end timing of the command injection period. For example, if a means for estimating the actual injection period is provided, the actual injection start timing and the actual injection end timing estimated by this means may be used.

  In the first embodiment, the command injection period is calculated from the command injection amount and the fuel pressure under the condition that the command injection period and the pumping period do not overlap, but instead of the above condition, the actual injection period And a condition that the pumping period does not overlap. In this case, the reference differential pressure ΔPs and differential pressure ΔPf may be set or detected separately for each of the two parameters of the command injection period TQ and the fuel pressure Ps.

  As a method for correcting the command injection period TQ based on the difference between the behavior of the fuel pressure detected when the fuel injection valve 16 is operated and the reference behavior, the above-described differential pressure ΔPf and the reference differential pressure ΔPs It is not restricted to what is performed based on the difference. For example, it may be performed based on the difference between the detected value and the reference value for the time integral value of the fuel pressure within the command injection period.

  As a method for correcting the operation amount of the fuel injection valve 16 based on the difference between the behavior of the fuel pressure detected when the fuel injection valve 16 is operated and the reference behavior, the method is to correct the command injection period TQ. Not exclusively. For example, the command injection amount may be corrected as the operation amount. That is, in this case, the final command injection amount is obtained by correcting the required injection amount calculated based on the accelerator pedal operation amount and the rotational speed detected by the accelerator sensor 24 based on the difference in behavior. do it. In this case, the command injection period is unambiguously determined by the final command injection amount.

  The fuel pump 6 is not limited to the one provided with the intake metering valve, but may be provided with a metering valve that adjusts the discharge amount when the fuel is discharged. The number of plungers is also arbitrary. Further, in each of the above embodiments, the fuel injection and the pressure feed correspond to one-to-one (synchronous type in which the pressure feed is synchronized with the fuel injection). However, the present invention is not limited to this, and the pressure feed is one-to-one with the fuel injection. It may be an asynchronous type that does not support it. However, when such an asynchronous type is used, the use of only the differential pressure ΔPf detected for each cylinder may not associate the fuel injection timing with the plunger involved in pressure feeding at a close timing. is there. For this reason, in order to compensate for the deviation of the actual injection amount from the command injection amount due to variations in the discharge characteristics of each plunger, the differential pressure ΔPf, etc., is detected for each plunger involved in pressure feeding. Is desirable.

  In addition, 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 of the fuel-injection control apparatus concerning this invention. The time chart which shows the fuel-injection timing concerning the embodiment. The time chart which illustrates the fluctuation | variation aspect of the fuel pressure in the common rail 12 accompanying the fuel injection concerning the embodiment. The flowchart which shows the procedure of the fuel-injection control concerning the embodiment. The figure which shows the three-dimensional map used in the embodiment. The figure which shows the memory | storage aspect of the differential pressure | voltage in the same embodiment. The time chart which shows the fuel-injection timing concerning 2nd Embodiment. The flowchart which shows the procedure of the fuel-injection control concerning 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 6 ... Fuel pump, 10 ... Inhalation metering valve, 12 ... Common rail, 16 ... Fuel injection valve, 30 ... ECU (one Embodiment of a fuel injection control apparatus).

Claims (6)

Fuel is operated by operating a fuel injection device that includes a pressure accumulating chamber that stores fuel in a high pressure state, a fuel pump that pressurizes and supplies fuel to the pressure accumulating chamber, and a fuel injection valve that injects fuel stored in the pressure accumulating chamber. In a fuel injection control device that performs injection control,
Means for capturing the detection result of the detection means for detecting the fuel pressure in the pressure accumulation chamber;
An operation amount setting means for setting an operation amount of the fuel injection valve based on a required injection amount which is a required value for the fuel injection amount and the detected fuel pressure;
Operating means for operating the fuel injection valve based on the operation amount set by the operation amount setting means;
A correction amount for correcting the operation amount is calculated based on a difference between a behavior of the fuel pressure detected when the fuel injection valve is operated by the operation amount and a reference behavior, and the operation unit performs the next time Correction means for correcting an operation amount in subsequent operations based on the correction amount ,
The fuel pump is provided with a plurality of plungers, and performs suction and pressurization of fuel by reciprocating movement of each plunger.
The correction means adds the correction amount calculated based on the difference between the behavior of the fuel pressure detected when the fuel injection valve is operated and the reference behavior, and the timing close to the timing of the operation. A fuel injection control device , wherein the correction amount specific to each plunger related to pressure supply is calculated by associating with a plunger related to pressure supply . Fuel is operated by operating a fuel injection device that includes a pressure accumulating chamber that stores fuel in a high pressure state, a fuel pump that pressurizes and supplies fuel to the pressure accumulating chamber, and a fuel injection valve that injects fuel stored in the pressure accumulating chamber. In a fuel injection control device that performs injection control,
Means for capturing the detection result of the detection means for detecting the fuel pressure in the pressure accumulation chamber;
An operation amount setting means for setting an operation amount of the fuel injection valve based on a required injection amount which is a required value for the fuel injection amount and the detected fuel pressure;
Operating means for operating the fuel injection valve based on the operation amount set by the operation amount setting means;
A correction amount for correcting the operation amount is calculated based on a difference between a behavior of the fuel pressure detected when the fuel injection valve is operated by the operation amount and a reference behavior, and the operation unit performs the next time Correction means for correcting an operation amount in subsequent operations based on the correction amount,
The correction means calculates, for each of the three parameters of fuel injection start timing, fuel pressure and injection period at the timing, a correction amount specific to each of these three parameters. apparatus. Fuel is operated by operating a fuel injection device that includes a pressure accumulating chamber that stores fuel in a high pressure state, a fuel pump that pressurizes and supplies fuel to the pressure accumulating chamber, and a fuel injection valve that injects fuel stored in the pressure accumulating chamber. In a fuel injection control device that performs injection control,
Means for capturing the detection result of the detection means for detecting the fuel pressure in the pressure accumulation chamber;
An operation amount setting means for setting an operation amount of the fuel injection valve based on a required injection amount which is a required value for the fuel injection amount and the detected fuel pressure;
Operating means for operating the fuel injection valve based on the operation amount set by the operation amount setting means;
A correction amount for correcting the operation amount is calculated based on a difference between a behavior of the fuel pressure detected when the fuel injection valve is operated by the operation amount and a reference behavior, and the operation unit performs the next time Correction means for correcting an operation amount in subsequent operations based on the correction amount,
The correction means includes a supply start timing calculation means for calculating a fuel supply start timing from the fuel pump based on an amount of fuel supplied from the fuel pump to the pressure accumulating chamber, a fuel injection start timing, and the required injection. And a reference value calculation means for calculating the reference behavior based on the amount, the supply start timing, and the supply amount . The fuel injection device includes a plurality of fuel injection valves,
The correction means calculates a correction amount specific to each fuel injection valve based on the difference between the behavior of the fuel pressure detected when each of the fuel injection valves is operated and the reference behavior. The fuel injection control device according to any one of claims 1 to 3 . 5. The fuel injection control according to claim 1, wherein the correction unit uses a fuel pressure detected at the end of fuel injection as a behavior of a fuel pressure provided for calculation of the correction amount. 6. apparatus. The correction means performs the correction based on a difference between a differential pressure between a fuel pressure detected at the start of fuel injection and a fuel pressure detected at the end of the injection, and a reference differential pressure as the reference behavior. The fuel injection control device according to claim 5, wherein an amount is calculated .

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