JP4788700B2 - Fuel injection control device and fuel injection system using the same - Google Patents

Description

  The present invention relates to a fuel injection control device that controls an injection amount of a fuel injection valve that performs multi-stage injection in one combustion cycle, and a fuel injection system using the same.

  In a common rail type fuel injection system, multistage injection is performed in which pilot injection, post injection, and the like are performed before and after the main injection that generates main torque for the purpose of reducing combustion noise or regenerating an exhaust filter. .

  Thus, in a multi-stage injection type fuel injection valve that injects fuel multiple times during one combustion cycle, pressure pulsation is generated by a water hammer effect when the fuel injection valve is closed and the injection is terminated in each stage. Since the magnitude of the pressure pulsation changes depending on the elapsed time from the end of each stage of injection, if a pressure pulsation occurs due to the preceding stage in multistage injection, the subsequent stage injection amount to be injected following the preceding stage injection It varies depending on the interval time from the end of injection to the start of subsequent injection.

Therefore, it is conceivable to measure the characteristics of the interval time and pressure pulsation in advance at the time of shipment and set a reference correction map for correcting the injection amount with respect to the interval time.
However, since the injection characteristics of the fuel injection valve vary due to machine differences or changes with time for each fuel injection valve, a deviation occurs between the target interval time and the actual interval time set in the reference correction map. As a result, even if the injection amount of the post-injection at the target interval time is corrected based on the reference correction map, the post-injection amount deviates from the target injection amount.

Further, in Patent Document 1, when performing multi-stage injection that combines pre-injection and main injection with a predetermined injection interval from pre-injection, in response to engine operating conditions such as engine speed and engine load, A technique that employs an injection pattern including an injection interval suitable for engine operating conditions is disclosed.
JP 2005-264810 A

  However, Patent Document 1 attempts to improve noise feeling and reduce noise by changing the frequency of engine vibration and noise by changing the injection interval. Therefore, the change in the injection interval in Patent Document 1 cannot correct the deviation in the interval time of the multistage injection due to machine differences or changes with time.

  The present invention has been made in order to solve the above-described problem, and uses a fuel injection control device that learns a shift in the interval time of multistage injection with a small learning amount with high accuracy over the entire range of use of the interval time. An object is to provide a fuel injection system.

As shown in FIG. 8A, the present inventor has different command injection amounts from 80 mm ³ / st, 40 mm ³ / st, 10 mm ³ / st, and 2 mm ³ / st, and the injection rate during injection and the fuel injection valve It was found that even if the internal pressure of (INJ) is different, the change in the internal pressure of the fuel injection valve after the end of injection, that is, the characteristics of pressure pulsation, are almost the same with respect to the elapsed time from the end of injection.

Then, as shown in FIG. 8B, the present inventor shows that the characteristic of the injection amount of the second-stage injection that changes due to the pressure pulsation generated at the end of the first-stage injection in the multistage injection is It has been found that even if the injection amount is different, if the injection end timing of the pre-stage injection and the command injection quantity of the post-stage injection are the same, the interval time between the pre-stage injection and the post-stage injection is almost the same. In FIG. 8B, the interval when the injection amount of the front-stage injection is changed to, for example, 50 mm ³ / st, 10 mm ³ / st, 2 mm ³ / st, and the command injection amount of the rear-stage injection is set to 2 mm ³ / st. The characteristic of the injection quantity of the latter stage injection with respect to time is shown. That is, the variation in the injection characteristic with respect to the interval time due to machine difference or change with time is caused only by the variation in the interval time due to the variation in the open / close valve delay time of the fuel injection valve. Therefore, the injection characteristic of the post-stage injection with respect to the interval time is not the deviation of the offset direction, the period, the amplitude, or the like, but only the phase of the reference injection characteristic is shifted.

Therefore, in the invention according to claims 1 to 6 , the reference injection characteristic for the interval time in the entire use range of the interval time between the pre-stage injection and the post-stage injection is stored, and from the acquisition data of the actual injection characteristic for the interval time, A feature point of actual injection characteristics corresponding to a feature point of reference injection characteristics is detected. Then, the phase difference between the reference injection characteristic and the actual injection characteristic is calculated from the characteristic point of the reference injection characteristic and the characteristic point of the actual injection characteristic. Here, the feature point represents a point that has a local feature on the injection characteristic and is easier to identify than other points on the injection characteristic.

  Thereby, even if the injection characteristics of the fuel injection valve vary due to machine differences or changes over time, it is possible to learn the interval time difference between the reference injection characteristics and the actual injection characteristics with high accuracy over the entire use range of the interval time.

Further, as described above, since the characteristic points of the injection characteristics are easier to identify than the other points of the injection characteristics, it is possible to reduce erroneous detection and detection errors of the characteristic points.
Further, since the feature point has a local feature on the injection characteristic, the feature point can be detected from the data of the actual injection characteristic in a part of the range, not the entire use range of the interval time. Thereby, since the feature point of the actual injection characteristic can be detected with a small number of data, the shift of the interval time can be learned with a small learning amount.

Further , according to the first to sixth aspects of the invention, the reference injection characteristic is corrected by shifting the phase difference between the reference injection characteristic and the actual injection characteristic, and the injection amount of the subsequent injection is corrected based on the corrected reference injection characteristic.
Thereby, the injection amount of the post-injection can be corrected with high accuracy based on the reference injection characteristics in which the shift of the interval time is corrected with high accuracy.

According to the second aspect of the present invention, the characteristic point is at least one of the maximum point and the minimum point of the reference injection characteristic and the actual injection characteristic.
Since the maximum point and the minimum point of the actual injection characteristic are feature points representing peaks on the waveform of the actual injection characteristic, the feature point of the actual injection characteristic can be detected with a small number of data. Thereby, the shift | offset | difference of interval time can be learned with a small learning amount.

  Furthermore, since the maximum point and the minimum point of the actual injection characteristic represent the peak on the waveform of the actual injection characteristic, it is possible to reduce erroneous detection and detection errors of feature points. Further, even if the actual injection characteristic is shifted in the offset direction due to a measurement error or the like, it is possible to easily detect the maximum point or the minimum point that is the peak of the actual injection characteristic.

According to the third and fourth aspects of the invention, the characteristic point is that the command injection amount and the actual injection amount coincide with each other in the reference injection characteristic and the actual injection characteristic.
The point where the command injection amount and the actual injection amount match is a point having a local characteristic on the injection characteristic, and thus the characteristic point of the actual injection characteristic can be detected with a small number of data. Thereby, the shift | offset | difference of interval time can be learned with a small learning amount.

Furthermore, since the point where the command injection amount and the actual injection amount coincide with each other has a remarkable feature, it is possible to reduce erroneous detection and detection errors of feature points.
Even when the change amount of the actual injection characteristic with respect to the interval time is small, if the feature point is that the command injection amount matches the actual injection amount, the feature point can be easily compared by comparing the command injection amount with the actual injection amount. Can be detected.

Further, the injection amount at the point where the command injection amount and the actual injection amount coincide with each other is smaller than the peak side of the actual injection characteristic where the actual injection amount increases with respect to the command injection amount. Thereby, according to invention of Claim 3 and 4 , the combustion noise when injecting from a fuel injection valve in order to detect the feature point of an actual injection characteristic can be reduced.

  By the way, when the phase difference between the reference injection characteristic and the actual injection characteristic is calculated from the phase difference between one feature point, the feature point of the actual injection characteristic is erroneously detected or the detection error is large. When the phase of the feature point deviates from the phase of the correct feature point, the phase shift of the detected feature point of the actual injection characteristic is directly reflected in the phase difference between the reference injection characteristic and the actual injection characteristic.

Therefore, according to the invention described in claim 5 , the phase difference calculating means calculates the phase difference between the reference injection characteristic and the actual injection characteristic from the plurality of feature points of the reference injection characteristic and the plurality of feature points of the actual injection characteristic. To do.

  Since the phase difference between the reference injection characteristic and the actual injection characteristic is calculated from a plurality of characteristic points of the reference injection characteristic and the actual injection characteristic, even when one feature point of the actual injection characteristic is erroneously detected or the detection error is large The phase difference between the reference injection characteristic and the actual injection characteristic can be calculated by reducing the phase shift of the characteristic point based on other characteristic points of the actual injection characteristic detected normally. For example, by calculating the phase difference between a plurality of feature points of the reference injection characteristics and the corresponding feature points of the actual injection characteristics, and averaging the calculated phase differences, the phase shift of the detected feature points is reduced. Thus, the phase difference between the reference injection characteristic and the actual injection characteristic can be calculated.

  The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel injection system according to an embodiment of the present invention is shown in FIG.
(Fuel injection system 10)
A fuel injection system 10 according to one embodiment of the present invention is shown in FIG.

  The accumulator fuel injection system 10 includes a feed pump 14, a high-pressure pump 16, a common rail 20, a fuel injection valve 30, an electronic control unit (ECU) 40, and the like. Fuel is injected into each cylinder.

  The feed pump 14 sucks fuel from the fuel tank 12 and supplies it to a high-pressure pump 16 that is a fuel supply pump. The high-pressure pump 16 is a known pump that pressurizes fuel sucked into a pressurizing chamber by a plunger reciprocatingly moved by a drive shaft interlocked with rotation of the crankshaft 66. By controlling the current value supplied to the metering valve 18 of the high-pressure pump 16 by the ECU 40, the fuel suction amount that the high-pressure pump 16 sucks in the suction stroke is metered. Then, by adjusting the fuel intake amount, the fuel discharge amount of the high-pressure pump 16 is adjusted.

  The common rail 20 accumulates fuel pumped by the high-pressure pump 16 and holds the fuel pressure at a predetermined high pressure according to the engine operating state. The pressure sensor 22 detects the fuel pressure inside the common rail 20 and outputs it to the ECU 40.

  The fuel injection valve 30 is installed in each cylinder of the four-cylinder diesel engine 60, and injects the fuel accumulated in the common rail 20 into the cylinder. The fuel injection valve 30 performs multi-stage injection including pilot injection, pre-injection, after-injection, and post-injection before and after the main injection that generates main torque in one combustion cycle of the diesel engine.

  As shown in FIG. 2, the fuel injection valve 30 is a known electromagnetically driven valve that controls the fuel injection amount by controlling the pressure in the control chamber 100 that applies fuel pressure to the nozzle needle 32 in the valve closing direction. . High pressure fuel is supplied from the common rail 20 to the periphery of the injection hole 34 of the fuel injection valve 30 and to the control chamber 100.

  In the state shown in FIG. 2 in which the control valve 36 blocks communication between the control chamber 100 and the low pressure side, the nozzle needle 32 closes the nozzle hole 34 by the fuel pressure applied from the control chamber 100 to the nozzle needle 32. .

  When the control valve 36 causes the control chamber 100 to communicate with the low pressure side, the amount of fuel flowing out from the control chamber 100 to the low pressure side becomes larger than the amount of fuel flowing into the control chamber 100 from the common rail 20. descend. As a result, the nozzle needle 32 is lifted and fuel is injected from the injection hole 34.

  As shown in FIG. 1, a microcomputer 50 mounted on an ECU 40 as a fuel injection control device includes a rewritable nonvolatile memory such as a CPU 52, a ROM 54, a RAM 56, and an EEPROM 58, various input / output ports, and the like. . A control program that causes the ECU 40 to function as actual injection characteristic acquisition means, feature point detection means, phase difference calculation means, phase correction means, and injection correction means, and reference injection characteristics for the interval time are stored as storage means such as the ROM 54 or the EEPROM 58. Stored in the device.

  The reference injection characteristics are set over the entire use range of the interval time between the front-stage injection and the rear-stage injection performed after the front-stage injection in the multi-stage injection. The reference injection characteristics may be stored as a map, or may be stored as a mathematical expression such as an approximate expression. In the case of a map, the reference injection characteristics can be acquired in a short time. In the case of the mathematical formula, the storage capacity for storing the reference injection characteristics becomes small. The reference injection characteristic is set for each predetermined pressure range of the common rail pressure in the case of a map, and the common rail pressure is set as a variable in the case of a mathematical expression.

  The ECU 40 determines the operating state of the diesel engine 60 from detection signals of various sensors such as an accelerator sensor that detects the opening (ACC) of the accelerator pedal, a temperature sensor, a pressure sensor 22, and an NE sensor that detects the engine speed (NE). get. The ECU 40 controls energization to the metering valve 18 and the fuel injection valve 30 based on the acquired engine operating state in order to control the diesel engine 60 to an optimal operating state.

  The ECU 40 controls the injection timing and the injection amount of each stage of the fuel injection valve 30 that performs multi-stage injection according to the engine operating state obtained from various sensors including the pressure sensor 22. The ECU 40 outputs a pulse signal as an injection command signal for controlling the injection timing and the injection amount of the fuel injection valve 30.

  The piston 64 accommodated in the cylinder 62 of the diesel engine 60 so as to be reciprocally movable is reciprocally driven when the fuel injected from the fuel injection valve 30 into the combustion chamber 110 burns and expands. The piston 64 is connected to the crankshaft 66 through a connecting rod 65. As the piston 64 reciprocates, the crankshaft 66 rotates.

  The inflow of intake air into the combustion chamber 110 is controlled by opening and closing the intake valve 70, and the exhaust discharged from the combustion chamber 110 is controlled by opening and closing the exhaust valve 74. The intake valve 70 and the exhaust valve 74 are driven to open and close by rotation of cams provided on the cam shafts 72 and 76.

(Change in injection amount due to pressure pulsation)
As shown in FIG. 3, when the fuel injection valve 30 is closed in the multi-stage injection and the pre-stage injection is completed, pressure pulsation is generated in the fuel in the fuel injection valve 30 by the water hammer action. Since this pressure pulsation is transmitted to the common rail 20 as well, the injection timing of the subsequent injection changes depending on the magnitude of the pressure pulsation. As a result, the injection amount of the subsequent injection changes depending on the magnitude of the pressure pulsation.

  Further, as shown in FIG. 4, a valve closing delay occurs in the closing of the pre-injection of the fuel injection valve 30 with respect to the falling timing of the drive current that is the injection command signal, and with respect to the rising timing of the driving current. A valve opening delay occurs in the opening of the subsequent injection of the fuel injection valve 30. Therefore, the target interval time (target INT) is set in consideration of the valve closing delay time Tde1 and the valve opening delay time Tds1 with respect to the command interval time (command INT) between the front injection and the rear injection commanded by the drive current. It is necessary. The target interval time is expressed by the following equation (1).

Target INT = command INT−Tde1 + Tds1 (1)
However, since the initial valve closing delay time Tde1 and the valve opening delay time Tds1 vary as Tde2 and Tds2 as indicated by reference numerals 210 and 212 due to machine differences or changes with time of the fuel injection valve 30, the target interval time and the actual interval A time lag indicated by (ΔINT1 + ΔINT2), that is, a phase difference occurs between the time points. As a result, if the post-injection injection amount is corrected at the target interval time point 220 without considering machine differences and changes over time, the post-injection injection amount is corrected at a point different from the actual interval time point 222 to be corrected. Will do.

  As described above, even if the command injection amount for the front stage injection is different and the injection rate during the injection and the internal pressure of the fuel injection valve 30 are different, the pressure pulsation characteristics are the interval time from the end of the front stage injection to the start of the rear stage injection. Is almost the same.

  The characteristic of the injection amount of the subsequent injection that changes due to the pressure pulsation is that the injection end timing of the preceding injection and the command injection amount of the subsequent injection are the same with respect to the interval time even if the injection amount of the preceding injection is different. Are almost identical. Therefore, even if the interval time varies due to machine differences or changes over time, the actual injection characteristic with respect to the interval time is only the phase of the reference injection characteristic shifted. Therefore, it is considered that the phase difference between the reference injection characteristic and the actually measured actual injection characteristic data is calculated, and the injection amount of the subsequent injection is corrected by the reference injection characteristic corrected by shifting the phase difference.

Further, even if there is a measurement error in the actual injection amount measured for obtaining the actual injection characteristic data, the actual injection characteristic data is obtained by shifting the reference injection characteristic in the offset direction.
(Each means of ECU40)
The ROM 54 or EEPROM 58 of the ECU 40 functions as storage means for storing reference injection characteristics described below. The ECU 40 functions as the following units according to a control program stored in a storage unit such as the ROM 54 or the EEPROM 58.

(1) Storage means In one combustion cycle, the correction value of the injection amount of the subsequent injection with respect to the entire use range of the interval time in the entire use range of the interval time between the pre-stage injection and the post-stage injection injected following the pre-stage injection, The reference injection characteristic is stored in the ROM 54 or the EEPROM 58. In the present embodiment, the correction value for the injection amount of the post-stage injection is a correction value for the falling timing of the injection command pulse width of the drive current that controls the injection quantity of the post-stage injection. Since the length of the injection command pulse width is changed by changing the falling timing of the injection command pulse width of the drive current, the injection amount of the post-stage injection is changed. The reference injection characteristics are initially set when the fuel injection valve 30 is shipped.

(2) Actual injection characteristic acquisition means The ECU 40 determines that the learning condition is satisfied if the accelerator-off non-injection deceleration operation is being performed, and the previous stage at a plurality of interval time points in a part of the interval time use range. The injection and the post-injection are followed by the post-injection, and the actual injection amount that is the total injection amount by the two-stage injection of the pre-injection and the post-injection is measured.

  A part of the use range of the interval time for performing the two-stage injection is a range in which the characteristic point of the actual injection characteristic corresponding to the characteristic point of the reference injection characteristic exists. Since the phase difference between the reference injection characteristic and the actual injection characteristic does not change abruptly due to changes over time, the characteristic point of the actual injection characteristic corresponding to the characteristic point of the reference injection characteristic is based on the previous phase difference learning results. The existing range can be specified and estimated to some extent.

  The ECU 40 detects a change in the engine speed due to the two-stage injection, converts the engine speed into engine torque, and further converts it into an injection quantity to measure the actual injection quantity. The ECU 40 calculates, for each measurement point, a correction value for the falling timing of the injection command pulse width of the drive current that controls the injection amount of the post-stage injection from the actual injection amount measured at each point of the interval time. As shown by “×”, it is acquired as actual injection characteristic data.

(3) Feature Point Detection Unit As shown in FIG. 5, as the feature point of the injection characteristic, any one of the maximum point 310, the minimum point 312 and the correction 0 point 314 of the reference injection characteristic 300 can be considered. The correction zero point is a point at which the command injection amount and the actual injection amount coincide with each other, and the correction value of the falling timing of the injection command pulse width of the drive current that controls the injection amount of the post-stage injection becomes zero.

  The maximum point, the minimum point, and the correction 0 point of the injection characteristic have locally remarkable characteristics on the injection characteristic. Therefore, it is not necessary to acquire data on the actual injection characteristics over the entire use range of the interval time in order to detect the maximum point, minimum point, and zero correction point of the actual injection characteristics. For example, in FIG. 5, it is estimated that the actual injection characteristic maximum point 320, minimum point 322, and correction 0 point 324 corresponding to the maximum point 310, the minimum point 312, and the correction 0 point 314 of the reference injection characteristic 300 exist. It is only necessary to measure the actual injection amount. Thereby, a feature point can be detected from the number of data with a small actual injection characteristic.

(3-1) Local maximum point and local minimum point When the local maximum point 320 or the local minimum point 322 of the actual injection characteristic is a feature point, the local maximum point 320 and the local minimum point 322 are peaks in the waveform of the injection characteristic and have local characteristics. Therefore, the maximum point 320 and the minimum point 322 can be easily detected with a small number of data of actual injection characteristics.

  Furthermore, since the maximum point 320 and the minimum point 322 of the actual injection characteristics represent peaks on the waveform of the actual injection characteristics, it is possible to reduce erroneous detection and detection errors of feature points. In addition, since the maximum point 320 and the minimum point 322 have remarkable characteristics on the waveform of the actual injection characteristic, even if the actual injection characteristic is shifted in the offset direction due to a measurement error or the like, the maximum point 320 and the peak of the actual injection characteristic The minimum point 322 can be easily detected.

(3-2) Correction 0 point When the correction 0 point 324 of the actual injection characteristic is a feature point, the correction 0 point 324 has a local characteristic in which the command injection amount and the actual injection amount coincide on the injection characteristic. Therefore, the correction 0 point 324 can be easily detected with a small number of data of the actual injection characteristics by comparing the command injection amount with the actual injection amount.

  Further, the correction 0 point 324 in which the command injection amount and the actual injection amount coincide with each other has a remarkable feature with respect to other points on the injection characteristic, and thus it is possible to reduce the misdetection and detection error of the feature point. .

Even when the change amount of the actual injection characteristic with respect to the interval time is small, the correction 0 point 324 can be easily detected by comparing the command injection amount with the actual injection amount.
Further, the injection amount at the correction 0 point 324 where the command injection amount and the actual injection amount coincide with each other is smaller than the minimum point 322 side of the actual injection characteristic in which the actual injection amount increases with respect to the command injection amount. Accordingly, when the correction 0 point 324 is a feature point, combustion noise when being injected from the fuel injection valve 30 in order to detect a feature point of actual injection characteristics can be reduced compared to the case where the minimum point 322 is a feature point. .

  Here, when there is a measurement error in the actual injection amount measured to detect the characteristic point of the actual injection characteristic, and the actual injection characteristic is shifted in the offset direction with respect to the reference injection characteristic as shown in FIG. 6 measurement point 326 may be erroneously detected as a correction 0 point 324.

  Accordingly, the actual injection amount is measured at a plurality of points between the local maximum point 320, the local minimum point 322, and the local maximum point 320 and the local minimum point 322 of the actual injection characteristic to calculate the correction value of the injection amount. It is conceivable that the value 330 is the correction 0 point 324.

(3-3) Multiple feature points When calculating the phase difference between the feature point of the reference injection characteristic and the feature point of the actual injection characteristic by the phase difference calculating means described below, the phase difference is calculated from the multiple feature points. It is desirable. In this case, the actual injection characteristic acquisition unit acquires data including a plurality of feature points of the actual injection characteristics corresponding to the plurality of feature points of the reference injection characteristics. Then, the feature point detecting means detects a plurality of feature points of the actual injection characteristics.

(4) Phase difference calculation means The ECU 40 calculates the phase difference between the reference injection characteristics and the actual injection characteristics from the feature points of the reference injection characteristics and the feature points of the actual injection characteristics detected by the feature point detection means. The ECU 40 can detect the phase difference with a small learning amount because the feature point detecting means detects the characteristic point from the small number of data of the actual injection characteristics.

  The ECU 40 may calculate the phase difference between one feature point of each of the reference injection characteristic and the actual injection characteristic, and obtain the phase difference between the reference injection characteristic and the actual injection characteristic, The phase difference between the characteristic points may be averaged to obtain the phase difference between the reference injection characteristic and the actual injection characteristic. When measuring a plurality of feature points, either a maximum point, a minimum point, or a correction 0 point, or a plurality of locations combining these feature points are measured.

  If the average of the phase differences of the characteristic points at a plurality of locations in the reference injection characteristics and the actual injection characteristics is used, if the feature points at one location of the actual injection characteristics are erroneously detected or the detection error is large, the feature points of the actual injection characteristics and the reference injection Even if an error occurs in the phase difference from the characteristic feature point, the detection error can be reduced by averaging the phase difference between the accurately measured actual injection characteristic feature point and the reference injection characteristic feature point.

(5) Phase correction means The ECU 40 corrects the reference injection characteristic by shifting the phase difference according to the phase difference between the reference injection characteristic calculated by the phase difference calculation means and the actual injection characteristic.

(6) Injection correction means The ECU 40 corrects the injection amount of the subsequent injection with high accuracy based on the reference injection characteristics whose phase is corrected with high accuracy.

(Interval time phase difference learning)
Next, the phase difference learning between the reference injection characteristic and the actual injection characteristic data with respect to the interval time will be described based on the learning routine of FIG. In FIG. 7, “S” represents a step. The learning routine shown in FIG. 7 is always executed during operation of the diesel engine 60.

  In S400, the ECU 40 determines whether or not a non-injection deceleration operation is being performed when the accelerator is off, as a phase difference learning condition. If the learning condition is not satisfied, the ECU 40 ends this routine.

  When the learning condition is satisfied, in S402, the ECU 40 is estimated that the characteristic points of the actual injection characteristics corresponding to the aforementioned maximum point 310, minimum point 312 and correction 0 point 314 exist as the characteristic points of the reference injection characteristic 300. In the partial use range of the interval time, the post-stage injection is performed after the pre-stage injection for each point, and the total injection quantity of the pre-stage and the post-stage is measured as the actual injection quantity.

  Then, the ECU 40 calculates, for each measurement point, a correction value for the falling timing of the injection command pulse width of the drive current that controls the injection amount of the post-stage injection from the actual injection amount measured at each interval time point. Obtained as characteristic data.

In S404, the ECU 40 detects the characteristic point of the actual injection characteristic corresponding to the characteristic point of the reference injection characteristic from the acquired actual injection characteristic data.
In S406, the ECU 40 calculates the phase difference between the reference injection characteristic and the actual injection characteristic from the characteristic point of the reference injection characteristic and the characteristic point of the actual injection characteristic.

In S408, the ECU 40 corrects the phase of the reference injection characteristic by shifting the calculated phase difference, and ends this routine.
The ECU 40 corrects the injection amount of the post-stage injection when performing the normal multi-stage injection based on the reference injection characteristic in which the phase difference is corrected in the phase difference learning routine of FIG.

  As described above, in this embodiment, even if the interval time varies due to machine differences or changes over time, the deviation of the reference injection characteristic with respect to the interval time is not the deviation of the offset direction, period, amplitude, etc., but only the phase direction. Focused on that. Then, by correcting the post-injection amount by shifting the reference injection characteristic with respect to the interval time in the entire use range of the interval time by the phase difference from the actual injection characteristic, the injection of the post-injection with high accuracy in the entire use range of the interval time The amount can be corrected.

  In addition, since the characteristic points of the actual injection characteristics can be detected from some actual injection characteristic data instead of the entire interval time usage range, the interval time deviation over the entire interval time usage range is highly accurate with a small amount of learning. To learn.

[Other Embodiments]
In the above-described embodiment, the injection amount of the post-stage injection is corrected by correcting the falling timing of the injection command signal for the post-stage injection and correcting the injection pulse width. On the other hand, the injection amount of the post-stage injection may be corrected by correcting only the injection timing without changing the pulse width of the injection command signal for the post-stage injection.

  Moreover, in the said embodiment, the correction value of the injection quantity of the back | latter stage injection with respect to interval time was employ | adopted as a reference | standard injection characteristic and an actual injection characteristic. On the other hand, you may employ | adopt the total injection quantity of the front | former stage injection and back | latter stage injection with respect to interval time as a reference | standard injection characteristic and an actual injection characteristic.

Moreover, you may combine each injection of multistage injection as post-stage injection injected after pre-stage injection and pre-stage injection.
As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

The block diagram which shows the fuel-injection system by this embodiment. The typical sectional view showing the composition of a fuel injection valve. Explanatory drawing explaining generation | occurrence | production of a pressure pulsation. The time chart explaining the gap | interval of interval time. Explanatory drawing which shows a response | compatibility with the feature point of a reference | standard injection characteristic, and the feature point of an actual injection characteristic. Explanatory drawing which shows the other correspondence of the feature point of a reference | standard injection characteristic, and the feature point of an actual injection characteristic. The flowchart which shows a phase difference learning routine. (A) shows the relationship between the elapsed time after the end of injection, the injection rate, and the pressure in the fuel injection valve, and (B) is a time chart showing the relationship between the interval time and the injection amount of the post-stage injection.

Explanation of symbols

10: fuel injection system, 16: high pressure pump (fuel supply pump), 20: common rail, 30: fuel injection valve, 40: ECU (fuel injection control device, storage means, actual injection characteristic acquisition means, feature point detection means, position (Phase difference calculation means, phase correction means, injection correction means), 54: ROM (storage means), 58: EEPROM (storage means), 60: diesel engine (internal combustion engine)

Claims (6)

In a fuel injection control device that controls an injection amount of a fuel injection valve that performs multi-stage injection during one combustion cycle,
Storage means for storing reference injection characteristics with respect to the interval time in the entire use range of the interval time between the preceding injection and the subsequent injection that is injected following the preceding injection;
Actual injection characteristic acquisition means for acquiring data of actual injection characteristics for the interval time;
Feature point detection means for detecting a feature point of the actual injection characteristic corresponding to a feature point of the reference injection characteristic with respect to the interval time from the data of the actual injection characteristic;
Phase difference calculating means for calculating a phase difference between the reference injection characteristic and the actual injection characteristic from the characteristic point of the reference injection characteristic and the characteristic point of the actual injection characteristic;
Phase correction means for correcting the reference injection characteristic by shifting the phase difference;
Injection correction means for correcting the injection amount of the post-stage injection based on the corrected reference injection characteristics;
A fuel injection control device comprising: 2. The fuel injection control device according to claim 1 , wherein the characteristic point is at least one of a maximum point and a minimum point of the reference injection characteristic and the actual injection characteristic . 2. The fuel injection control device according to claim 1 , wherein the characteristic point is a point where a command injection amount and an actual injection amount coincide in the reference injection characteristic and the actual injection characteristic . The reference injection characteristic and the actual injection characteristic represent a relationship between the interval time and a correction value of an injection amount of the post-stage injection, and the characteristic point is a point where the correction value is zero. the fuel injection control apparatus according to 3. The phase difference calculating means calculates a phase difference between the reference injection characteristic and the actual injection characteristic from the plurality of feature points of the reference injection characteristic and the plurality of feature points of the actual injection characteristic. The fuel injection control device according to any one of claims 1 to 4 . A fuel supply pump that pressurizes and pumps fuel; and
A common rail for accumulating fuel pumped by the fuel supply pump;
A fuel injection valve for injecting fuel accumulated in the common rail into a cylinder of an internal combustion engine;
A fuel injection control device according to any one of claims 1 to 5,
A fuel injection system comprising:

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