JP5799895B2 - Fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control device applied to a fuel injection system including a fuel injection valve and a fuel pressure sensor that detects a pressure of fuel supplied to the fuel injection valve.

  Feedback control is performed on the operation of the fuel injection valve in order to perform appropriate fuel injection control in accordance with the injection characteristics from time to time including changes in the characteristics of the fuel injection valve over time.

  For example, Patent Document 1 sets an injection command signal from a target injection state using a learning value, and detects an actual injection state with respect to the set injection command signal. Then, the operation of the fuel injection valve is feedback-controlled by updating the learning value according to the actual injection state.

JP 2009-52414 A

  By the way, when the fuel injection valve is deteriorated or the injection hole is clogged when the target injection amount is very small, the injection state is not detected and the injection state cannot be detected. In such a case, it is determined that there is no injection and the learning value is not updated, so the injection command signal is not updated. Therefore, there is a possibility that the non-injection state continues and the target injection amount and the actual injection amount continue to deviate.

  In view of the above circumstances, the present invention suppresses the deviation between the target injection amount and the actual injection amount even when the target injection amount is very small, and enables fuel injection control capable of performing feedback control with high injection amount accuracy. An object is to provide an apparatus.

In order to solve the above-described problems, the present invention provides a fuel injection valve that injects more fuel to be burned in a diesel engine as the drive period is longer. A back pressure chamber for applying pressure to the end, and an actuator for controlling the connection state of the high pressure passage and the low pressure passage communicating with the back pressure chamber to increase or decrease the pressure in the back pressure chamber to drive the needle valve And a fuel pressure sensor that sequentially detects a fuel pressure supplied to the fuel injection valve, and is a variation with respect to time of an injection rate at the time of injection by the fuel injection valve. Storage means for storing a parameter for specifying an injection rate waveform as a learned value, and the fuel injection according to a target injection amount based on the learned value stored in the storage means A signal setting means for setting a command signal for the drive period, a drive means for driving the fuel injection valve by the command signal, and a fuel pressure detected by the fuel pressure sensor when the fuel injection valve is driven by the drive means. A pressure waveform detecting means for detecting a pressure waveform that is a variation of the fuel pressure with respect to time, a non-injection determining means for determining whether or not the fuel injection valve is driven by the driving means, and the non-injection determining means; The parameter corresponding to the target injection amount is calculated based on the pressure waveform detected by the pressure waveform detecting means on the condition that the non-injection state is determined by the non-injection determining means, and the parameter is used. The learning means for updating the learning value stored in the storage means and the non-injection determining means determine that there is no injection. Case, the until it is determined not to be a non-injection state by an injection determining means, and a correcting means for correcting the command signal so as to increase the driving period.

According to the present invention, a parameter for specifying the injection rate waveform is stored as a learned value, and a command signal for the drive period of the fuel injection valve corresponding to the target injection amount is set based on the stored learned value. The The fuel injection valve is driven by the set command signal, and the pressure waveform is detected based on the fuel pressure detected by the fuel pressure sensor when the fuel injection valve is driven.

  If it is determined that the fuel injection valve is not in the non-injection state, a parameter corresponding to the target injection amount is calculated based on the detected pressure waveform, and the stored learning value is calculated using the calculated parameter. Updated. On the other hand, if it is determined that there is no injection state, the learning value is not updated.

However, according to the present invention, when it is determined that there is no injection, the drive period is extended until it is determined that there is no injection. If it is determined that the fuel is not in the non-injection state again, learning of parameters is resumed and the learning value is updated. Then, the command signal is appropriately updated based on the updated learning value. Therefore, according to the present invention, it is possible to suppress the target injection amount and the actual injection amount from continuing to deviate and perform feedback control of the fuel injection valve with high injection amount accuracy.

The figure which shows the outline of a fuel-injection system. The figure which shows the change of the injection rate and fuel pressure corresponding to an injection command signal. The block diagram which shows the outline | summary of the learning of an injection rate parameter, and the setting of a command signal. The block diagram which shows the outline | summary of the fuel-injection control in 1st Embodiment. The flowchart which shows the procedure of the correction process of the command signal in 1st Embodiment. The time chart which shows the execution aspect of the correction process of the command signal in 1st Embodiment. The block diagram which shows the outline | summary of the fuel-injection control in 2nd and 3rd embodiment. The flowchart which shows the correction | amendment procedure of the command signal in 2nd Embodiment. The flowchart which shows the correction | amendment procedure of the command signal in 3rd Embodiment.

  Hereinafter, embodiments embodying a fuel injection control device will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
First, an outline of a fuel injection system to which a fuel injection control device is applied will be described with reference to FIG. The fuel injection system according to this embodiment is assumed to be mounted on a four-cylinder diesel engine. The fuel injection system includes a fuel injection valve 10 mounted on each cylinder # 1 to # 4 of the engine, and a fuel pressure mounted on each fuel injection valve 10 and sequentially detecting the fuel pressure supplied to each fuel injection valve 10. A sensor 20, an ECU 30 (electronic control unit), and a fuel tank 40 are provided.

  The fuel tank 40 is a tank for storing fuel (light oil) supplied to the cylinders # 1 to # 4 of the engine. The fuel in the fuel tank 40 is pumped to the common rail 42 and accumulated by a fuel pump 41 driven in conjunction with the crankshaft of the engine. The pressure in the common rail 42 becomes the fuel supply pressure Pc supplied to the fuel injection valve 10 of each cylinder. The fuel accumulated in the common rail 42 is distributed and supplied to the fuel injection valve 10 of each cylinder. The fuel injection valve 10 of each cylinder sequentially injects fuel in a preset order.

  The fuel injection valve 10 includes a body 11, a needle valve 12, and an actuator 13 such as an electromagnetic coil or a piezo element. The body 11 is formed therein with a high pressure passage 11a, a low pressure passage 11d, and an injection hole 11b connected to the high pressure passage 11a. The fuel supplied from the common rail 42 is injected from the injection hole 11b through the high-pressure passage 11a. The needle valve 12 is accommodated inside the body and opens and closes the nozzle hole 11b.

  Further, the body 11 is formed with a back pressure chamber 11 c for applying a back pressure to the needle valve 12. The high pressure passage 11a and the low pressure passage 11d are connected to the back pressure chamber 11c. The communication state between the high pressure passage 11 a and the low pressure passage 11 d and the back pressure chamber 11 c is switched by the control valve 14.

  Specifically, when the actuator 13 is energized, the control valve 14 is pushed down to the nozzle hole 11b side. As a result, the back pressure chamber 11c communicates with the low pressure passage 11d, so that the fuel pressure in the back pressure chamber 11c decreases and the back pressure that presses the needle valve 12 toward the nozzle hole 11b decreases. As a result, the seat surface 12a of the needle valve 12 is separated from the seat surface 11e of the body 11 formed so as to be connected to the injection hole 11b, so that fuel is injected from the injection hole 11b.

  On the other hand, when the power supply to the actuator 13 is turned off, the control valve 14 is pushed up to the actuator 13 side. As a result, the back pressure chamber 11c communicates with the high pressure passage 11a, so that the fuel pressure in the back pressure chamber 11c increases, and the back pressure that presses the needle valve 12 toward the nozzle hole 11b increases. As a result, the seat surface 12a of the needle valve 12 is seated on the seat surface 11e of the body 11, so that fuel injection from the injection hole 11b is stopped.

  Therefore, when the drive period of the actuator 13 is controlled by the drive period command signal, the injection amount of the fuel injected from the nozzle hole 11b is controlled.

  The fuel pressure sensor 20 is mounted on each fuel injection valve 10 and includes a stem 21 (distortion body) and a pressure sensor element 22. The stem 21 is attached to the body 11 and has a diaphragm portion 21a. The diaphragm portion 21a is elastically deformed by receiving the pressure of the high-pressure fuel flowing through the high-pressure passage 11a. The pressure sensor element 22 is attached to the diaphragm portion 21a, and transmits a pressure signal corresponding to the elastic deformation amount of the diaphragm portion 21a to the ECU 30.

  The ECU 30 (fuel injection control device) includes a storage unit, a signal setting unit, a driving unit, a pressure waveform detection unit, a non-injection determination unit, a learning unit, a correction unit, and an actual injection amount according to the present embodiment. Calculating means. The ECU 30 includes a main microcomputer 34 and a sub microcomputer 35. The main microcomputer 34 and the sub microcomputer 35 are each configured as a well-known microcomputer including a CPU and a memory (ROM, RAM).

  The ECU 30 calculates the target injection state based on the accelerator pedal operation amount, the engine load, the engine speed, and the like. For example, the optimal injection state corresponding to the engine load and the engine speed is stored as an injection state map. Based on the current engine load and engine speed, the target injection state is calculated with reference to the injection state map. Further, command signals Tq, t1 (see FIG. 2A) corresponding to the calculated target injection state are set based on injection rate parameters td, te, Rα, Rβ, Rmax, which will be described later, and output to the fuel injection valve 10. Thus, the operation of the fuel injection valve 10 is controlled.

  Further, based on the detection value of the fuel pressure sensor 20, a change in the fuel pressure caused by the injection is detected as a pressure waveform Wb (see FIG. 2C), and the fuel injection rate with respect to time is detected based on the detected pressure waveform Wb. The injection rate waveform (see FIG. 2B) representing the fluctuation is calculated to detect the injection state. Then, the injection rate parameters Rα, Rβ, and Rmax that specify the detected injection rate waveform (injection state) are learned, and the correlation between the command signal (drive period Tq and drive start timing t1) and the injection state is specified. The injection rate parameters td and te are learned.

  Specifically, in the pressure waveform, a descending approximation line that approximates a descending waveform from the inflection point P1 at which the fuel pressure drop starts at the start of injection to the inflection point P2 at which the descent ends by a least square method or the like. Lα is calculated. Then, a time (a crossing time LBα between Lα and Bα) that is the reference value Bα in the descending approximate straight line Lα is calculated. Focusing on the fact that the intersection time LBα and the injection start time R1 are highly correlated, the injection start time R1 is calculated based on the intersection time LBα. For example, a timing that is a predetermined delay time Cα before the intersection timing LBα may be calculated as the injection start timing R1.

  In addition, among the pressure waveforms, a rising approximate line Lβ is calculated by approximating the rising waveform from the inflection point P3 at which the fuel pressure rises at the end of the injection to the inflection point P5 at which the descent ends by a least square method or the like. To do. Then, a time (intersection time LBβ between Lβ and Bβ) that is the reference value Bβ in the rising approximate straight line Lβ is calculated. Focusing on the fact that the intersection timing LBβ and the injection end timing R4 are highly correlated, the injection end timing R4 is calculated based on the intersection timing LBβ. For example, a timing that is a predetermined delay time Cβ before the intersection timing LBβ may be calculated as the injection end timing R4.

  Next, paying attention to the fact that the slope of the descending approximate line Lα and the slope of the injection rate increase are highly correlated, the slope of the straight line Rα indicating the increase in the injection rate waveform shown in FIG. Calculation is based on the slope of Lα. For example, the slope of Rα may be calculated by multiplying the slope of Lα by a predetermined coefficient. Similarly, since the slope of the rising approximate line Lβ and the slope of the injection rate decrease are highly correlated, the slope of the straight line Rβ indicating the decrease in injection in the injection rate waveform is calculated based on the slope of the rising approximate line Lβ.

  Next, based on the straight lines Rα and Rβ of the injection rate waveform, a timing (valve closing operation start timing R23) at which the needle valve 12 starts lift-down in response to the command to end the injection is calculated. Specifically, the intersection of both straight lines Rα and Rβ is calculated, and the intersection timing is calculated as the valve closing operation start timing R23. Further, a delay time (injection start delay time td) with respect to the drive start timing t1 of the injection start timing R1 is calculated. Further, a delay time (injection end delay time te) with respect to the injection end command timing t2 of the valve closing operation start timing R23 is calculated.

  Further, the pressure corresponding to the intersection of the descending approximate straight line Lα and the ascending approximate straight line Lβ is calculated as the intersection pressure Pαβ, and a pressure difference ΔPγ between the reference pressure Pbase and the intersection pressure Pαβ, which will be described in detail later, is calculated. Focusing on the fact that the correlation with the maximum injection rate Rmax is high, the maximum injection rate Rmax is calculated based on the pressure difference ΔPγ. Specifically, the maximum injection rate Rmax is calculated by multiplying the pressure difference ΔPγ by the correlation coefficient Cγ. However, in the case of the small injection in which the pressure difference ΔPγ is less than the predetermined value ΔPγth, Rmax = ΔPγ × Cγ is set as described above, while in the case of the large injection in which ΔPγ ≧ ΔPγth, it is set in advance. The value (set value Rγ) is calculated as the maximum injection rate Rmax.

  The “small injection” is assumed to be an injection in which the needle valve 12 starts to be lifted down before the injection rate reaches Rγ. The fuel is throttled by the seat surfaces 11e and 12a, and the injection amount The injection rate when is limited is the maximum injection rate Rmax. On the other hand, the “large injection” is assumed to be an injection in which the needle valve 12 starts to be lifted down after the injection rate reaches Rγ, and the fuel is throttled at the injection hole 11b to limit the injection amount. The injection rate when the fuel injection is being performed becomes the maximum injection rate Rmax. In short, when the valve opening state is continued even after the driving period Tq is sufficiently long and the maximum injection rate is reached, the injection rate waveform becomes trapezoidal as shown in FIG. On the other hand, in the case of small injection that starts the valve closing operation before reaching the maximum injection rate, the injection rate waveform is a triangle.

  As described above, the injection rate parameters td, te, Rα, Rβ, and Rmax can be calculated from the pressure waveform. Based on the learned values of the injection rate parameters td, te, Rα, Rβ, and Rmax, an injection rate waveform (see FIG. 2B) corresponding to the command signal (see FIG. 2A) is calculated. Can do. Since the area of the injection rate waveform calculated in this way (see halftone dot hatching in FIG. 2B) corresponds to the injection amount, the injection amount can also be calculated based on the injection rate parameter.

  Here, based on the detection value of the fuel pressure sensor 20, a procedure for detecting a change in the fuel pressure caused by the injection as the pressure waveform Wb will be briefly described. The detection value of the fuel pressure sensor 20 is a pressure waveform composed of a plurality of detection values acquired at a predetermined sampling cycle. The pressure waveform detected by the fuel pressure sensor 20 is referred to as an injection pressure waveform Wa.

  The pressure waveform Wa during the injection is not a waveform that represents only the influence of the injection. For example, when pump pumping is performed during fuel injection, the pressure waveform during injection during the pumping period becomes a waveform in which the pressure is increased as a whole. Even if such pump pumping is not performed during fuel injection, immediately after the fuel is injected, the fuel pressure in the entire injection system is reduced by that amount. That is, the injection pressure waveform Wa includes components of a pressure waveform Wb representing a change in fuel pressure caused by the injection and a pressure waveform representing a change in the fuel pressure in the entire injection system, that is, a change in the fuel pressure in the common rail 42. It can be said that. The pressure waveform in the common rail 42 is represented as a non-injection pressure waveform Wu detected by the fuel pressure sensor 20 mounted on the non-injection cylinder.

  Therefore, the non-injection pressure waveform Wu detected by the fuel pressure sensor 20 mounted on the non-injection cylinder is subtracted from the injection pressure waveform Wa detected by the fuel pressure sensor 20 mounted on the injection cylinder, which is caused by the injection. The pressure waveform Wb is detected. In addition, the pressure waveform shown in FIG.2 (c) is the pressure waveform Wb which arises with injection. Further, the average fuel pressure of the portion of the pressure waveform Wb until the fuel pressure starts decreasing with the start of injection is calculated as the reference pressure Pbase.

  FIG. 3 is a block diagram showing an outline of learning of the injection rate parameter, setting of the command signal, and the like. Each means 31 and 32 functioning by the ECU 30 will be described below.

  The learning means 31 detects the pressure waveform Wb based on the fuel pressure detected by the fuel pressure sensor 20 on the condition that it is determined that the fuel is not in the non-injection state, and the injection rate parameters td, te, Rα based on the pressure waveform Wb. , Rβ, Rmax are calculated. And the learning value memorize | stored in the memory of the main microcomputer 34 is updated using the calculated injection rate parameter. Since the injection rate parameter varies depending on the supply pressure Pc (pressure in the common rail 42) at that time, the injection rate parameter can be learned in association with the supply pressure Pc or the reference pressure Pbase (see FIG. 2C). desirable. In the example of FIG. 3, the injection rate parameter value corresponding to the supply pressure Pc is stored in the injection rate parameter map M.

  The signal setting means 32 acquires an injection rate parameter (learned value) corresponding to the current fuel pressure from the injection rate parameter map M. Then, based on the acquired injection rate parameter, command signals Tq, t1 corresponding to the target injection state are set. When the fuel injection valve 10 is operated according to the command signal set in this way, the learning unit 31 detects the pressure waveform Wb based on the fuel pressure detected by the fuel pressure sensor 20. Further, the learning means 31 calculates injection rate parameters td, te, Rα, Rβ, Rmax based on the detected pressure waveform Wb.

  In short, the actual injection state (that is, injection rate parameters td, te, Rα, Rβ, Rmax) with respect to the command signal is detected and learned, and the command signal corresponding to the target injection state is set based on the learned value. Therefore, the command signal is feedback-controlled based on the actual injection state, and the fuel injection state is controlled with high accuracy so that the actual injection state matches the target injection state even if the fuel injection valve 10 is deteriorated over time. it can. However, if it is determined that there is no injection, the learning value is not updated.

  If the injection hole 11b of the fuel injection valve 10 is clogged, it may be determined that there is no injection when the target injection amount Qtrg is small and the drive period Tq set accordingly is short. If it is determined that there is no injection state, the learning value is not updated. If the learning value is not updated, the command signal Tq set based on the learning value is not updated. Therefore, the non-injection state continues, and the target injection amount Qtrg and the actual injection amount Qdet may continue to deviate.

  Therefore, when it is determined that there is no injection state, the command signal Tq is corrected so as to extend the drive period until it is determined that there is no injection state. FIG. 4 is a block diagram showing an overview of feedback control of fuel injection executed by the fuel injection control device according to the present embodiment.

  In B12, the fuel injection valve 10 is driven by the driving means according to the command signals Tq, t1. When fuel is injected from the fuel injection valve 10, the pressure waveform detection unit detects the pressure waveform Wb based on the fuel pressure detected by the fuel pressure sensor 20. Furthermore, it is determined by the non-injection determination means whether or not there is a non-injection state. Specifically, it is determined whether or not the condition of the non-injection state is satisfied, and it is determined that the condition is the non-injection state when the condition of the non-injection state is satisfied. Examples of the condition of the non-injection state include that the pressure waveform Wb is a flat shape and that the engine rotation speed does not increase due to combustion.

  If it is determined in B12 that there is no injection state, in B13, the learning means 31 calculates an injection rate parameter corresponding to the target injection amount Qtrg based on the pressure waveform Wb. In B14, the actual injection amount calculation means calculates the injection rate waveform using the injection rate parameter calculated in B13, and calculates the actual injection amount Qdet actually injected. Subsequently, in B10, the learning means 31 updates the learning value stored for each supply pressure Pc using the injection rate parameter calculated in B13. By storing the learning value for each supply pressure Pc, it is possible to perform feedback control of the fuel injection valve 10 with higher stability.

  Subsequently, in B11, the signal setting means 32 sets the command signals Tq, t1 corresponding to the target injection state including the target injection amount Qtrg based on the updated learning value. Subsequently, in B12, the fuel injection valve 10 is driven by the command signal Tq, t1 set in B11 by the driving means. And until it determines with it being a non-injection state, the process of B15 and B16 is not performed but the process of B10-B14 is performed repeatedly.

  On the other hand, if it is determined in B12 that there is no injection, the injection rate parameter is not calculated in B13. In B14, the actual injection amount Qdet is set to zero. Subsequently, in B10, since the injection rate parameter is not calculated in B13, the learning value is not updated. Therefore, in B11, command signals Tq, t1 corresponding to the target injection state including the target injection amount Qtrg are set based on the learning value that has not been updated.

  When the fuel injection valve 10 is driven by the command signals Tq, t1 set based on the learning value that has not been updated, it is determined again that there is no injection, and the learning value is not updated. Therefore, when it is determined that there is no injection state as in the conventional case, if the processing of B10 to B14 is repeated, the target injection amount Qtrg increases and the drive period Tq continues to be determined, and the non-injection state continues to be determined. The learning value is not updated. That is, the target injection amount Qtrg and the actual injection amount Qdet continue to deviate until the target injection amount Qtrg increases.

  Therefore, if it is determined in B12 that there is no injection, the command signal Tq, t1 is set in B11, and then in B15-16, the command signal Tq, t1 is corrected by the correcting means so that the drive period Tq is lengthened. . In B15, the correction amount of the driving period Tq, that is, the extension period ΔTq is calculated. A method for calculating ΔTq will be described later. In B16, a corrected drive period Tqf = Tq + ΔTq is calculated.

  Subsequently, in B12, the fuel injection valve 10 is driven by the command signals Tqf, t1. Then, the drive period Tq is extended for each correction, and the processes of B10 to B16 are repeated until it is determined that there is no non-injection state.

  After it is determined that the non-injection state is not obtained in B12 by resuming the fuel injection, the processing of B10 to B16 is repeated until the learning completion condition described later is satisfied, and the command signal Tq is corrected. After the learning completion condition is satisfied, the correction of the command signal Tq is finished. That is, the processes of B10 to B14 are repeatedly performed without performing the processes of B15 and B16. In addition, the main microcomputer 34 with which ECU30 is provided performs the process of B10-B16.

  Next, the correction process of the command signal Tq executed by the injection control apparatus according to the present embodiment will be described with reference to the flowchart of FIG. This correction process is executed for each fuel injection valve 10 mounted in each cylinder # 1 to # 4 of the engine. The processes of S11 to S14 are executed by the sub microcomputer 35, the processes of S16 to S17 are executed by the main microcomputer 34, and the process of S15 is executed by the sub microcomputer 35 and the main microcomputer 34. First, in S11, it is determined whether or not an error is detected in the fuel injection system. If an error is detected (NO), the correction process of the command signal Tq is terminated. If no error is detected (YES), the process proceeds to the next S12.

  In S12, it is determined whether it is determined that there is no injection or whether learning is not completed. The learning here is learning that starts after the injection is restarted after it is determined that there is no injection. It is determined whether the learning completion condition is satisfied. If the learning completion condition is satisfied, it is determined that learning is completed. The learning completion condition is that the deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet is smaller than the threshold value, and the extension period ΔTq of the driving period Tq is smaller than the threshold value. If it is determined that there is no non-injection state and learning is complete (NO), the correction process is terminated. If it is determined that there is no injection or if learning is not completed (YES), the process proceeds to the next S13.

  In S13, a deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet is calculated. In subsequent S14, the correction value Qcor is calculated from the map M10 according to the deviation ΔQ and the supply pressure Pc calculated in S13. The left column of the map M10 represents the deviation ΔQ, and the upper row represents the supply pressure Pc. The map M10 stores a correction value Qcor associated with the deviation ΔQ and the supply pressure Pc. The correction value Qcor is a positive value when the target injection amount Qtrg is larger than the actual injection amount Qdet, and is a negative value when the target injection amount Qtrg is smaller than the actual injection amount Qdet.

  In S15, the correction value Qcor is transmitted from the sub-microcomputer 35 to the main microcomputer 34. In step S16, the main microcomputer 34 that has received the correction value Qcor adds the correction value Qcor to the extension period ΔTq calculated in the previous correction process to calculate a new extension period ΔTq. Therefore, the extension period ΔTq is a total value obtained by adding the correction value Qcor set according to the deviation ΔQ and the supply pressure Pc every time correction is started. That is, the extension period ΔTq is a value corresponding to the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. Therefore, after the injection is resumed, the parameter is learned, and the command signal Tq is corrected so as to reduce the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. .

  Therefore, when the correction is started, the actual injection amount Qdet increases until it once becomes larger than the target injection amount Qtrg, and then decreases and approaches the target injection amount Qtrg. Further, the extension period ΔTq increases until the target injection amount Qtrg and the actual injection amount Qdet coincide with each other, then decreases and approaches 0 (see FIG. 6A). When the deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet is smaller than the threshold value and the extension period ΔTq of the drive period Tq is smaller than the threshold value, the learning completion condition is satisfied. Here, both of these threshold values are set to zero. Note that the processing of S16 corresponds to the processing of B15 in FIG.

  Next, in S17, the command period Tqf after correction is calculated by adding the extension period ΔTq calculated in S16 to the command signal Tq installed based on the learned value. The process of S17 corresponds to the process of B16 in FIG. This is the end of the correction process.

  FIG. 6 shows (a) target injection amount Qtrg (broken line) and actual injection amount Qdet (solid line), (b) deviation ΔQ, (c) extension period ΔTq, (d) when the correction process of FIG. 5 is executed. The time change of the command signal Tq is shown.

  Before the time point t11, the target injection amount Qtrg and the actual injection amount Qdet are substantially the same, and the deviation ΔQ and the extension period ΔTq are zero. However, when the target injection amount Qtrg decreases at the time point t11, the actual injection amount Qdet becomes 0 accordingly and the non-injection state is entered.

  Therefore, it is determined that there is no injection at time t11. Therefore, the command signal Tq is not updated until the injection is resumed after being set according to the reduced target injection amount Qtrg. On the other hand, since it is determined that there is no injection, the correction process of the command signal Tq is started, so that the extension period ΔTq starts to increase. Therefore, after time t1, the fuel injection valve 10 is driven by the corrected command signal Tqf obtained by extending the command signal Tq set based on the learning value by the extension period ΔTq.

  Next, at time t12, the actual injection amount Qdet becomes larger than zero. That is, at time t12, the injection is restarted, and it is determined that there is no non-injection state. Thereby, the learning of the parameter is resumed, and the update of the command signal Tq set based on the learned value is also resumed. Further, since the injection is resumed, the actual injection amount Qdet starts to increase and the deviation ΔQ starts to decrease after time t12. At this time, since the target injection amount Qtrg is larger than the actual injection amount Qdet, the extension period ΔTq is calculated by adding a positive correction value Qcor to the extension period ΔTq at the previous correction. Therefore, the extension period ΔTq continues to increase after time t12.

  Next, at the time t13, the target injection amount Qtrg and the actual injection amount Qdet match. Therefore, the deviation ΔQ becomes zero. However, in the period t11 to t13, the total amount of the target injection amount Qtrg is larger than the total amount of the actual injection amount Qdet. Since the extension period ΔTq is a value corresponding to the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period, the correction for extending the command signal Tq is continued after time t3. Accordingly, since the actual injection amount Qdet becomes larger than the target injection amount Qtrg after the time point t3, the extension period ΔTq is calculated by adding the negative correction value Qcor to the extension period ΔTq at the previous correction. Therefore, the extension period ΔTq starts to decrease from time t3.

  Subsequently, at time t14, the absolute values of the actual injection amount Qdet and the deviation ΔQ are maximized. Then, after time t14, the actual injection amount Qdet starts to decrease so as to approach the target injection amount Qtrg.

  Subsequently, at time t15, the actual injection amount Qdet and the target injection amount Qtrg substantially coincide with each other, and the deviation ΔQ becomes zero. Also, the extension period ΔTq becomes zero. Therefore, the learning completion condition is satisfied at time t15, and learning is completed. Therefore, the command signal Tq is not corrected after time t15. That is, based on the learned value, the fuel injection valve 10 is driven by the command signal Tq set in the drive period corresponding to the target injection amount. In the present embodiment, the two threshold values of the learning completion condition are set to 0. However, the threshold value may be a sufficiently small value if it is not 0. If the threshold value is sufficiently small, the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction periods t11 to t15 can be reduced.

  The first embodiment described above has the following effects.

  When it is determined that there is no injection state, the drive period Tq is extended until it is determined that there is no injection state. If it is determined that the fuel is not in the non-injection state again, learning of parameters is resumed and the learning value is updated. Then, the command signal Tq is also appropriately updated based on the updated learning value. Therefore, it is possible to suppress the target injection amount Qtrg and the actual injection amount Qdet from continuing to deviate and perform feedback control of the fuel injection valve 10 with high injection amount accuracy.

  The command signal Tq is corrected by a total value obtained by adding the correction value Qcor set according to the deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet every time correction is started. That is, the drive period Tq is extended at each correction time point according to the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. Therefore, after it is determined that the injection is resumed and the state is not the non-injection state, the drive Tq is learned so that the parameter is learned and the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period is reduced. Can be corrected. Further, since the correction value Qcor is set according to the supply pressure Pc, the overshoot amount of the actual injection amount Qdet in the period t13 to t15 is suppressed, and feedback control of the highly stable fuel injection valve 10 can be performed. .

  When the deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet is smaller than the threshold and the extension period ΔTq of the drive period Tq is shorter than the threshold, the total amount of the target injection amount Qtrg and the actual injection amount in the correction period It can be determined that the difference from the total amount of Qdet has been reduced. Therefore, when the learning is completed, the injection state of the fuel injection valve 10 can be changed to an injection state suitable for the driving situation.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. FIG. 7 is a block diagram showing an outline of feedback control of fuel injection executed by the fuel injection control device according to the present embodiment. The processing performed at B20 to B24 and B26 is the same as the processing performed at B10 to B14 and B16 in FIG. However, in B25, the extension period ΔTq is calculated by a calculation method different from B15 in FIG. A method of calculating the extension period ΔTq in the second embodiment will be described with reference to the flowchart of FIG. The correction process shown in FIG. 8 is executed for each fuel injection valve 10 mounted in each cylinder # 1 to # 4 of the engine. Hereinafter, description of the same processing as in the first embodiment will be omitted, and different processing will be described.

  In S21 to S23, the same processing as S11 to S13 in FIG. 5 is performed to calculate the deviation ΔQ. Next, in S24, the deviation ΔQ calculated in S23 is added to the total value Qitg calculated in the previous correction to calculate a new total value Qitg. The map M12 stores the total value Qitg associated with the engine cylinders # 1 to # 4 and the supply pressure Pc. For each correction, the deviation M is added to the total value Qitg stored in the map M12 according to the cylinder of the engine and the supply pressure Pc, and the map M12 is updated. Therefore, the total value Qitg is a value obtained by adding the deviation ΔQ every time the correction is started after the correction is started. The left column of the map M12 represents the engine cylinder, and the upper row represents the supply pressure Pc.

  In S25, the total value Qitg calculated in S24 is transmitted from the sub-microcomputer 35 to the main microcomputer 34. Subsequent processing of S26 and S27 is executed by the main microcomputer 34.

  In S26, the extension period ΔTq is calculated by multiplying the total value Qitg by a constant gain. Therefore, the extension period ΔTq is a value obtained by multiplying the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period by a constant gain. Therefore, after the injection is resumed, the parameter is learned, and the command signal Tq is corrected so as to reduce the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. .

  Therefore, when the correction is started, the actual injection amount Qdet is once increased until it becomes larger than the target injection amount Qtrg, and then decreased to approach the target injection amount Qtrg. Further, the extension period ΔTq is increased until the target injection amount Qtrg and the actual injection amount Qdet coincide with each other, and then is decreased and approaches zero.

  Subsequently, in S27, the corrected command signal Tqf is calculated as in S17 of FIG.

  In this embodiment, since the extension period ΔTq is calculated by multiplying the total value Qitg by a constant gain, feedback control with high responsiveness is achieved. The execution mode of the correction process in the present embodiment can shorten the correction period (correction periods t11 to t15 in FIG. 6) compared to the execution mode in FIG. On the other hand, the maximum value of the overshoot amount of the actual injection amount Qdet (the absolute value of the deviation ΔQ at time t4 in FIG. 6) increases. Further, since the extension period ΔTq is calculated by applying a constant gain, it is not necessary to calculate the gain from the map, and simple feedback control is achieved.

  According to 2nd Embodiment described above, there exist the following effects.

  The command signal Tq is corrected by a value obtained by multiplying the total value Qitg, which is obtained by adding the deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet every time correction is started, to a certain gain. . That is, the drive period Tq is extended at each correction time point according to the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. Therefore, after it is determined that the injection is restarted and not in the non-injection state, the parameters are learned, and the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period is reduced. The driving period Tq can be corrected. Further, since the gain applied to the total value Qitg is a constant value, it is possible to perform a simple feedback control of the fuel injection valve with high responsiveness.

(Third embodiment)
Next, a process different from the second embodiment will be described with reference to the flowchart of FIG. 9 in the third embodiment. In S31 to S34, the total value Qitg is calculated as in S21 to S24 of FIG.

  Next, in S35, the deviation ΔQ calculated in S33 and the total value Qitg calculated in S34 are transmitted from the sub-microcomputer 35 to the main microcomputer 34.

  Subsequently, in S36, the extension period ΔTq is calculated by multiplying the total value Qitg by a gain set according to the deviation ΔQ and the supply pressure Pc. Since the gain is stored in the map M11 in association with the deviation ΔQ and the supply pressure Pc, the genin is calculated from the map M11 according to the deviation ΔQ and the supply pressure Pc. The left column of the map M11 represents the deviation ΔQ, and the upper row represents the supply pressure Pc.

  Therefore, the extension period ΔTq is a value obtained by multiplying the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period by a gain set according to the deviation ΔQ and the supply pressure Pc. Therefore, after the injection is resumed, the parameter is learned, and the command signal Tq is corrected so as to reduce the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. .

  Therefore, when the correction is started, the actual injection amount Qdet is once increased until it becomes larger than the target injection amount Qtrg, and then decreased to approach the target injection amount Qtrg. Further, the extension period ΔTq is increased until the target injection amount Qtrg and the actual injection amount Qdet coincide with each other, and then is decreased and approaches zero.

  Subsequently, in S37, the corrected command signal Tqf is calculated as in S27 of FIG.

  In the present embodiment, since the extension period ΔTq is calculated by multiplying the total value Qitg by a gain set according to the deviation ΔQ and the supply pressure Pc, as in the first embodiment, highly stable feedback is performed. It becomes control. Therefore, the execution mode of the correction process in the present embodiment is the same as the execution mode of FIG.

  According to 3rd Embodiment described above, there exist the following effects.

  A gain set according to the deviation ΔQ and the supply pressure Pc is applied to the total value Qitg obtained by adding the deviation ΔQ between the target injection amount Qtrg and the actual injection amount Qdet each time correction is started. The command signal Tq is corrected by the obtained value. That is, the drive period Tq is extended at each correction time point according to the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period. Therefore, after it is determined that the injection is restarted and not in the non-injection state, the parameters are learned, and the difference between the total amount of the target injection amount Qtrg and the total amount of the actual injection amount Qdet in the correction period is reduced. The driving period Tq can be corrected. Further, since the gain applied to the total value Qitg is set according to the deviation ΔQ and the supply pressure Pc, highly stable feedback control of the fuel injection valve can be performed.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows.

  In each of the above embodiments, the command signal Tq may be corrected on condition that the target injection amount Qtrg is smaller than a predetermined value. If it does in this way, when it determines with a non-injection state by factors other than the fuel injection valve 10, it can suppress performing correction | amendment of the command signal Tq accidentally.

  In each of the above embodiments, the sub-microcomputer 35 may perform processing until the extension period ΔTq is calculated (S17, S27, S37), and the extension period ΔTq may be transmitted from the sub-microcomputer 35 to the main microcomputer 34.

  The main microcomputer 34 and the sub microcomputer 35 may be provided in separate ECUs.

  ΔQ: Deviation, ΔTq: Extension period, 10: Fuel injection valve, 13: Actuator, 20: Fuel pressure sensor, 30: ECU, 42: Common rail, Qdet: Actual injection amount, Qtrg: Target injection amount, Wb: Pressure waveform.

Claims (7)

A fuel injection valve (10 ) for injecting more fuel to be burned in a diesel engine as the drive period is longer, a needle valve (12) for opening and closing an injection hole (11b) for injecting fuel, and at the end of this needle valve The back pressure chamber (11c) for applying pressure, and the connection state of the high pressure passage (11a) and the low pressure passage (11d) communicating with the back pressure chamber are controlled to increase or decrease the pressure in the back pressure chamber. Applied to a fuel injection system comprising: a fuel injection valve having an actuator (13) for driving the valve; and a fuel pressure sensor (20) for sequentially detecting the fuel pressure supplied to the fuel injection valve,
Storage means for storing, as a learning value, a parameter for specifying an injection rate waveform that is a variation with respect to time of an injection rate at the time of injection by the fuel injection valve;
A signal setting means (32) for setting a command signal for the drive period so as to inject the fuel according to a target injection amount based on the learning value stored in the storage means;
Driving means for driving the fuel injection valve by the command signal;
Pressure waveform detection means for detecting a pressure waveform that is a variation of fuel pressure with respect to time based on the fuel pressure detected by the fuel pressure sensor when the fuel injection valve is driven by the drive means;
Non-injection determination means for determining whether or not the fuel injection valve is driven by the driving means when in the non-injection state;
The parameter corresponding to the target injection amount is calculated based on the pressure waveform detected by the pressure waveform detection means on the condition that the non-injection state is determined by the no-injection determination means, and the parameter Learning means (31) for updating the learning value stored in the storage means using
When it is determined by the non-injection determination means that the non-injection state has been reached, the command to extend the drive period until the next injection is determined by the non-injection determination means to be non-injection state. Correction means for correcting the signal;
A fuel injection control device (30) comprising: An actual injection amount calculating means for calculating an actual injection amount of the fuel injected when the fuel injection valve is driven by the driving means using the parameter calculated by the learning means;
The correction means uses a correction value set according to a deviation between the target injection amount and the actual injection amount and a supply pressure of fuel supplied to the fuel injection valve after the correction is started. The fuel injection control device according to claim 1, wherein the command signal is corrected by a total value added at each correction. An actual injection amount calculating means for calculating the actual injection amount of the fuel injected when the fuel injection valve is driven by the driving means using the parameter calculated by the learning means;
The correction means corrects the command signal with a value obtained by multiplying a total value obtained by adding a deviation between the target injection amount and the actual injection amount every time the correction is started and a constant gain. The fuel injection control device according to claim 1. An actual injection amount calculating means for calculating the actual injection amount of the fuel injected when the fuel injection valve is driven by the driving means using the parameter calculated by the learning means;
The correction means is configured to add the deviation between the target injection amount and the actual injection amount to the total value obtained by adding each time the correction is started after the correction is started, and the amount of fuel supplied to the fuel injection valve. The fuel injection control device according to claim 1, wherein the command signal is corrected by a value obtained by multiplying a gain set in accordance with a supply pressure.   The correction unit completes updating of the learning value by the learning unit on condition that a deviation between the target injection amount and the actual injection amount is smaller than a threshold value and an extension period of the driving period is shorter than the threshold value. The fuel injection control device according to any one of claims 2 to 4.   The fuel injection control device according to claim 1, wherein the correction unit performs the correction on the condition that the target injection amount is smaller than a predetermined value.   The fuel injection control device according to any one of claims 1 to 6, wherein the learning value is stored for each supply pressure of fuel supplied to the fuel injection valve.

Images