JP2014227858A - Fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of highly accurately extracting the fluctuation waveform of a fuel pressure caused by injection, from a fluctuation waveform detected by a fuel pressure sensor during injection.SOLUTION: A fuel injection control device includes: injection sensor waveform detecting means for detecting an injection sensor waveform Wi on the basis of the output of a fuel pressure sensor 20 corresponding to a predetermined cylinder when injection is performed in the predetermined cylinder in the steady operation state of an internal combustion engine; non-injection sensor waveform detecting means for detecting a non-injection sensor waveform Wa on the basis of the output of the fuel pressure sensor 20 corresponding to the predetermined cylinder when injection is performed in a cylinder different from the predetermined cylinder in the steady operation state of the internal combustion engine; and injection waveform extracting means for subtracting the non-injection sensor waveform Wa detected by the non-injection sensor waveform detecting means from the injection sensor waveform Wi detected by the injection sensor waveform detecting means, and extracting an injection waveform W showing a pressure fluctuation caused by the injection performed in the predetermined cylinder.

Description

  The present invention relates to a fuel injection control device that is applied to a fuel injection system that includes a fuel injection valve provided in each cylinder of a multi-cylinder internal combustion engine and that performs fuel injection using high-pressure fuel stored in a stock pressure vessel. .

  In a fuel injection system that distributes and supplies fuel from a common rail (stock pressure vessel) to a plurality of fuel injection valves, when fuel is injected from the fuel injection valve, the fuel pressure inside the fuel injection valve changes in accordance with the change in the injection rate. . Therefore, a fuel pressure sensor mounted on each fuel injection valve detects a fluctuation waveform of fuel pressure at the time of injection, and estimates a waveform indicating a change in injection rate based on the detected fluctuation waveform.

  However, in the fluctuation waveform detected by the fuel pressure sensor, the pressure fluctuation caused by the fuel pump from the fuel pump and the pressure fluctuation caused by the pressure in the common rail decreasing by the amount of fuel injection are superimposed as disturbances. Yes. Therefore, in order to detect the actual injection state with high accuracy, it is necessary to remove the disturbance component from the fluctuation waveform detected by the fuel pressure sensor and extract the fluctuation waveform of the fuel pressure resulting from the injection.

  Therefore, Patent Document 1 subtracts the non-injection fluctuation waveform detected by the fuel pressure sensor provided in the non-injection cylinder at the same time from the fluctuation waveform detected by the fuel pressure sensor provided in the injection cylinder. The resulting fuel pressure change is extracted.

Japanese Patent No. 4678397

  Patent Document 1 subtracts a fluctuation waveform detected for a cylinder different from the injection cylinder from a fluctuation waveform detected for the injection cylinder. However, even if the fluctuation waveform detected for the cylinder different from the injection cylinder is subtracted from the fluctuation waveform detected for the injection cylinder due to hardware variations, the accuracy of extracting the fluctuation waveform of the fuel pressure caused by the injection May decrease.

  In view of the above circumstances, the present invention mainly provides a fuel injection control device that can extract a fluctuation waveform of fuel pressure caused by injection with high accuracy from a fluctuation waveform detected by a fuel pressure sensor during injection. Objective.

  In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a pressure-holding vessel that holds high-pressure fuel under pressure, a fuel pump that pumps fuel to the pressure-pressure vessel, and a cylinder of a multi-cylinder internal combustion engine A fuel injection valve that injects high-pressure fuel that is provided in the animal pressure vessel and is held at the animal pressure, and a fuel pressure that detects a fuel pressure in each fuel passage from the animal pressure vessel to the injection port of each fuel injection valve A fuel injection control device applied to a fuel injection system comprising a sensor, wherein the fuel pressure sensor corresponding to the predetermined cylinder when injection is performed in the predetermined cylinder in a steady operation state of the engine An injection sensor waveform detecting means for detecting an injection sensor waveform based on the output of the engine, and in the steady operation state of the engine, when the injection is performed in a cylinder different from the predetermined cylinder, the predetermined cylinder Based on the output of the corresponding fuel pressure sensor, the non-injection sensor waveform detection means for detecting the non-injection sensor waveform, and the non-injection sensor waveform detected by the injection sensor waveform detection means, A non-injection sensor waveform detected by the sensor waveform, and an injection waveform extraction means for extracting an injection waveform representing a pressure fluctuation caused by injection in the predetermined cylinder.

  According to the first aspect of the present invention, fuel is pumped from the fuel pump to the animal pressure vessel. The high-pressure fuel held in the animal pressure vessel is injected by a fuel injection valve provided in each cylinder. The fuel pressure in each fuel passage from the stock pressure vessel to the injection port of the fuel injection valve of each cylinder is detected by a fuel pressure sensor.

  When injection is performed in a predetermined cylinder in a steady operation state of the internal combustion engine, a sensor waveform during injection in which disturbance is superimposed on pressure fluctuation caused by injection is based on the output of the fuel pressure sensor corresponding to the predetermined cylinder. Detected. Further, when injection is performed in a cylinder different from the predetermined cylinder in the above-described steady operation state of the internal combustion engine, the non-representation of the disturbance component of the pressure fluctuation is based on the output of the fuel pressure sensor corresponding to the predetermined cylinder. A sensor waveform during injection is detected.

  Here, if the non-injection sensor waveform can be detected simultaneously with the injection sensor waveform for the same cylinder, the non-injection sensor waveform is the optimum non-injection sensor waveform representing the disturbance superimposed on the injection sensor waveform. Become. However, the sensor waveform during injection and the sensor waveform during non-injection cannot be detected simultaneously for the same cylinder. Therefore, in the steady operation state of the internal combustion engine, the sensor waveform during injection and the sensor waveform during non-injection for the same cylinder are acquired at different timings. If the internal combustion engine is in a steady operation state, a non-injection sensor waveform of a predetermined cylinder can be acquired under the same conditions as when a predetermined cylinder is injected. And the waveform at the time of injection showing the pressure fluctuation resulting from injection is extracted from the sensor waveform at the time of injection and the sensor waveform at the time of non-injection for the cylinder with the same hardware characteristic. Therefore, it is possible to extract the fuel pressure fluctuation caused by the injection with high accuracy from the sensor waveform during injection in which the disturbance is superimposed on the pressure fluctuation caused by the injection.

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 time chart which shows the sensor waveform at the time of injection, and the sensor waveform at the time of non-injection. The flowchart which shows the process sequence which extracts the waveform at the time of injection which concerns on 1st Embodiment. The time chart which shows the sensor waveform at the time of injection stop, the sensor waveform at the time of non-injection, the sensor waveform at the time of injection, and the waveform at the time of injection. The flowchart which shows the process sequence which extracts the waveform at the time of injection which concerns on 2nd Embodiment.

(First embodiment)
Hereinafter, embodiments in which a fuel injection control device is mounted on a vehicle will be described with reference to the drawings. FIG. 1 shows a configuration of a fuel injection system to which the fuel injection control device according to the present embodiment is applied. This fuel injection system is assumed to be mounted on a four-cylinder diesel engine (multi-cylinder internal combustion engine). This fuel injection system includes a common rail 42 (stock pressure vessel) that holds high pressure fuel under pressure, a fuel pump 41 that pumps fuel to the common rail 42, and fuel provided in each cylinder # 1 to # 4 of the engine. An injection valve 10 and a fuel pressure sensor 20 that sequentially detects the fuel pressure in each fuel passage from the common rail 42 to the injection port of each fuel injection valve 10 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 and held 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 through a pipe 43 (fuel passage). 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 has a high pressure passage 11a (fuel passage), a low pressure passage 11d, and an injection hole 11b (injection port) 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 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 (a strain generating body), a pressure sensor element 22, and a communication circuit 22a. 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 from the communication circuit 22a to the ECU 30.

  The ECU 30 (fuel injection control device) is configured as a microcomputer including a CPU, a ROM, a RAM, an I / O, a bus line connecting these, and the like. The RAM is a main memory, and the ROM is a program memory. 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.

  In addition, the ECU 30 realizes functions as an injection sensor waveform detection means, a non-injection sensor waveform detection means, and an injection waveform extraction means, which will be described later, by the CPU executing a program stored in the ROM.

  Further, the ECU 30 is based on an injection waveform W (refer to FIG. 2C) representing a pressure variation caused by injection, and an injection rate waveform representing a variation of the fuel injection rate with respect to time (refer to FIG. 2B). Is calculated to detect the injection state. The injection waveform W is extracted by an injection waveform extraction means to be described later based on the detection value by the fuel pressure sensor 20. The ECU 30 calculates injection rate parameters td, te, Rα, Rβ, Rmax from the injection rate waveform. The injection rate parameters td, te, Rα, Rβ, and Rmax are respectively the injection start delay time with respect to the timing when the injection is commanded, the injection end delay time with respect to the timing when the injection end is commanded, the injection rate increasing slope, and the injection rate. The downward slope and maximum injection rate.

  The ECU 30 learns these injection rate parameters td, te, Rα, Rβ, Rmax, and based on the learned values of the injection rate parameters td, te, Rα, Rβ, Rmax, the injection command signal (see FIG. 2A). The injection rate waveform corresponding to (see FIG. 2B) is calculated. Further, an injection rate parameter Q representing the injection amount is calculated from the calculated area of the injection rate waveform (see halftone dot hatching in FIG. 2B).

  Next, the injection sensor waveform detection means, the non-injection sensor waveform detection means, and the injection waveform extraction means will be described. Hereinafter, the injection cylinder is a cylinder in which the fuel injection valve 10 provided in the cylinder injects fuel, and the non-injection cylinder is the fuel injection valve 10 provided in the cylinder injecting fuel. There are no cylinders.

  The injection sensor waveform detection means detects the injection sensor waveform Wi based on the output of the fuel pressure sensor 20 corresponding to the injection cylinder among the cylinders # 1 to # 4 in the steady operation state of the engine. FIG. 3A shows an in-injection sensor waveform Wi detected for the cylinder # 1 when the injection is performed in the cylinder # 1 (predetermined cylinder). This injection sensor waveform Wi is a fluctuation waveform of the fuel pressure in which a disturbance is superimposed on the fluctuation of the fuel pressure caused by the injection. Specifically, in period A, disturbance due to pumping is superimposed on the waveform W during injection, and in period B, disturbance due to pressure drop in the common rail 42 is superimposed on the waveform W during injection. . The steady operation state of the engine means that the engine speed, the fuel supply pressure Pc, and the fuel injection amount Q are substantially constant.

  The non-injection sensor waveform detection means outputs the output of the fuel pressure sensor 20 corresponding to the non-injection cylinder among the cylinders # 1 to 4 in the same steady operation state as when the injection sensor waveform Wi is acquired by the injection sensor waveform detection means. Based on this, the non-injection sensor waveform Wa is detected. The non-injection sensor waveform Wa is a fluctuation waveform representing a fluctuation in fuel pressure caused by the fuel pump 41 pumping fuel and a fluctuation in fuel pressure that occurs as the pressure in the common rail 42 decreases by the amount of fuel injection in the injection cylinder. is there. The non-injection sensor waveform Wa shown in FIG. 3B is obtained when the cylinder # 1 is in the non-injection state, that is, when the injection is performed in any of the cylinders # 2 to # 4, This is a non-injection sensor waveform Wa detected for the cylinder # 1 under the same conditions.

  The in-injection waveform extraction means is the non-injection time detected for the cylinder # 1 by the non-injection sensor waveform detection means from the injection-time sensor waveform Wi detected by the injection-time sensor waveform detection means. The sensor waveform Wa is subtracted to extract the waveform W during injection. That is, the injection waveform extraction means extracts the injection waveform W by removing the disturbance component from the injection sensor waveform Wi.

  Next, the processing procedure for extracting the waveform W during injection will be described with reference to the flowchart of FIG. This process is repeatedly executed by the ECU 30 at predetermined intervals.

  First, in S11, it is determined whether or not the engine is in a steady operation state, that is, in a steady travel state. As described above, the sensor waveform Wi during injection and the sensor waveform Wa during non-injection cannot be detected simultaneously. Therefore, it is necessary to make the operating state of the engine when detecting the sensor waveform Wi during injection the same as the operating state of the engine when detecting the non-injection sensor waveform Wa. Specifically, when the engine speed, the fuel supply pressure Pc, and the change amount of the fuel injection amount Q are smaller than the threshold value, it is determined as steady running, and when the change amount is larger than the threshold value, it is steady. It is determined that the vehicle is not running. If it is not steady running (NO), this process ends. If it is steady running (YES), the process proceeds to S12.

  Next, in S12, the injection sensor waveform Wi of the target cylinder detected by the injection sensor waveform detection means is stored in the RAM. Next, in S13, the non-injection sensor waveform Wa of the target cylinder detected by the non-injection sensor waveform detection means at the time of injection of cylinders other than the target cylinder is stored in the RAM.

  Next, in S14, the injection waveform extraction means extracts the injection waveform W by subtracting the non-injection sensor waveform Wa stored in S13 from the injection sensor waveform Wi stored in S12. Specifically, since the sensor waveform Wi at the time of injection and the sensor waveform Wa at the time of non-injection are not detected at the same time, the reference CA of the sensor waveform Wi at the time of injection and the reference CA of the sensor waveform Wa at the time of non-injection are combined. The non-injection sensor waveform Wa is subtracted from the sensor waveform Wi. The injection waveform extraction means is for the cylinders having the same hardware characteristics from the injection sensor waveform Wi and the non-injection sensor waveform Wa detected under the same conditions, and represents the pressure fluctuation caused by the injection. The waveform W is extracted. This process is complete | finished above.

  According to 1st Embodiment described above, there exist the following effects.

  In the steady operation state of the engine, the sensor waveform Wi during injection and the sensor waveform Wa during non-injection for a predetermined cylinder are acquired at different timings. If the engine is in a steady operation state, the non-injection sensor waveform Wa of the predetermined cylinder can be acquired under the same conditions as when the predetermined cylinder is injected. Then, an injection waveform W representing a pressure fluctuation caused by injection is extracted from the injection sensor waveform Wi and the non-injection sensor waveform Wa for cylinders having the same hardware characteristics. Therefore, it is possible to extract the fuel pressure fluctuation caused by the injection with high accuracy from the sensor waveform Wi during injection in which the disturbance is superimposed on the pressure fluctuation caused by the injection.

(Second Embodiment)
Next, a difference between the second embodiment and the first embodiment will be described. In the second embodiment, the ECU 30 causes the CPU to execute a program stored in the ROM, so that the sensor waveform detection means during injection, the sensor waveform detection means during non-injection, the waveform extraction means during injection, and the sensor waveform detection during injection stop are detected. The function as the means and the advance correction means is realized. In 2nd Embodiment, it is limited to when the pumping timing by the fuel pump 41 and the injection timing by the fuel injection valve 10 do not overlap.

  The injection stop time sensor waveform detection means is based on the output of the fuel pressure sensor 20 corresponding to the predetermined cylinder when the injection is stopped at the injection timing of the predetermined cylinder in the steady operation state of the engine. Wb is detected.

  The advance angle correction means determines the phase of the non-injection sensor waveform Wa detected by the non-injection sensor waveform detection means in accordance with the length of the fuel passage between the predetermined cylinder and the cylinder in which the injection is performed. , Correct to advance.

  Next, a processing procedure for extracting the waveform W during injection will be described with reference to the flowchart of FIG. This process is repeatedly executed by the ECU 30 at predetermined intervals. In this process, during a predetermined period including the injection period, the pressure pumping by the fuel pump 41 and the injection by the fuel injection valve 10 are sequentially performed.

  First, in S21, it is determined whether or not the vehicle is in a steady running state as in S11. If it is not steady running (NO), this process ends. If it is always running (YES), the process proceeds to S22.

  Next, in S22, when the injection is stopped at the injection timing of the target cylinder, the injection stop time sensor waveform Wb detected by the injection stop time sensor waveform detection means is stored in the RAM. FIG. 5A shows an injection stop-time sensor waveform Wb detected for the cylinder # 1 when the injection is stopped at the injection timing of the cylinder # 1. The injection stop time sensor waveform Wb is detected in a state where the injection of all cylinders is stopped. Therefore, the fuel pressure fluctuation accompanying the pressure drop in the common rail 42 by the amount corresponding to the fuel injection is not superimposed on the injection stop time sensor waveform Wb, and only the fuel pressure fluctuation accompanying the pressure feeding is superimposed. In S22, the sensor waveform Wb at the time of injection stop in the pumping period in the predetermined period is stored in the RAM. FIG. 5A shows an injection stop time sensor waveform Wb stored in the RAM.

  Next, in S23, the injection sensor waveform Wi of the target cylinder detected by the non-injection sensor waveform detection means is stored in the RAM. FIG. 5B shows a non-injection sensor waveform Wa detected for the cylinder # 1 when the injection is performed in any of the cylinders # 2 to # 4. In S23, the non-injection sensor waveform Wa during the injection period of the predetermined period is stored in the RAM. FIG. 5B shows a non-injection sensor waveform Wa stored in the RAM.

  Next, in S24, the injection sensor waveform Wi of the target cylinder detected by the injection sensor waveform detection means at the time of injection of the target cylinder is stored in the RAM. FIG. 5C shows an in-injection sensor waveform Wi detected for the cylinder # 1 when the injection is performed in the cylinder # 1. In S24, the sensor waveform Wi during injection for a predetermined period is stored in the RAM. FIG. 5C is different in time scale from FIG. 5A and FIG. 5B, and shows an injection-time sensor waveform Wi in a predetermined period.

  Next, in S25, the injection waveform extraction means subtracts the injection stop sensor waveform Wb stored in S22 and the non-injection sensor waveform Wa stored in S23 from the injection sensor waveform Wi stored in S24. The time waveform W is extracted. Specifically, as shown in FIG. 5C, the sensor waveform Wb at the time of injection stop is subtracted from the sensor waveform Wi at the time of injection in the pumping period, and the sensor waveform Wa at the time of non-injection is subtracted from the sensor waveform Wi at the time of injection in the injection period.

  Here, when the predetermined cylinder is the cylinder # 1 and the injection is performed in any of the cylinders # 2 to # 4, the pressure fluctuation caused when the pressure in the common rail decreases is the cylinder # 2 to # 4. Is transmitted to the fuel pressure sensor 20 corresponding to the cylinder # 1 with a time delay corresponding to the length of the fuel passage between the cylinder # 1 and the cylinder # 1. Therefore, the advance angle correcting means adjusts the phase of the non-injection sensor waveform Wa in accordance with the length of the fuel passage between the cylinder # 1 and the cylinder in which injection is performed among the cylinders # 2 to # 4. Advance. Then, the sensor waveform Wb at the time of injection stop is subtracted from the sensor waveform Wi at the time of injection in the pumping period, and the sensor waveform Wa at the time of injection corrected by the advance correction means is subtracted from the sensor waveform Wi at the time of injection in the injection period. Extract W. FIG. 5D shows the extracted waveform W at the time of injection.

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

  Based on the output of the fuel pressure sensor 20 corresponding to a predetermined cylinder when injection of a predetermined cylinder is stopped in a steady operation state of the engine when the fuel pumping timing and the fuel injection timing do not overlap. A sensor waveform Wb at the time of injection stop representing a pressure fluctuation accompanying the pressure feeding is detected. Further, the non-injection sensor waveform Wa representing the pressure fluctuation caused by the pressure in the common rail 42 decreasing and the stop sensor waveform Wb representing the pressure fluctuation accompanying the pumping are subtracted from the injection sensor waveform Wi, A waveform W at the time of injection representing a pressure fluctuation caused by the injection is extracted. Therefore, the pressure fluctuation resulting from the injection can be extracted with high accuracy.

  When the injection is performed in a cylinder different from the predetermined cylinder, the pressure fluctuation caused when the pressure in the common rail 42 decreases corresponds to the predetermined cylinder with a time delay corresponding to the length of the fuel passage. Propagated to the pressure sensor 20. Therefore, the phase of the non-injection sensor waveform Wa is corrected to advance in accordance with the length of the fuel passage between the predetermined cylinder and the cylinder in which the injection is performed. Thereby, the pressure fluctuation resulting from injection can be extracted with higher accuracy.

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

  In the first embodiment, the fuel pumping timing and the fuel injection timing may overlap.

  In the second embodiment, although the extraction accuracy is inferior to the case of advance correction of the non-injection sensor waveform Wa, the non-injection sensor waveform Wa that has not been advanced is subtracted from the injection sensor waveform Wi in the injection period. The waveform W at the time of injection may be extracted.

  -The fuel injection system may be mounted not only on a diesel engine but also on a gasoline engine or a gas engine. The fuel injection system may be mounted on an engine other than the four cylinders. Further, the fuel injection system is not limited to a vehicle engine, and may be mounted on an engine such as a ship.

  DESCRIPTION OF SYMBOLS 10 ... Fuel injection valve, 11a ... High pressure passage, 11b ... Injection hole, 20 ... Fuel pressure sensor, 30 ... ECU, 41 ... Fuel pump, 42 ... Common rail, W ... Waveform at injection, Wa ... Sensor waveform at non-injection, Wi ... Sensor waveform during injection.

Claims (3)

An animal pressure vessel (42) for holding high-pressure fuel under pressure, a fuel pump (41) for pumping fuel to the animal pressure vessel, and an accumulator provided in each cylinder of a multi-cylinder internal combustion engine. A fuel injection valve (10) for injecting high-pressure fuel maintained at pressure, and a fuel pressure in each fuel passage (43, 11a) from the animal pressure vessel to the injection port (11b) of each fuel injection valve are detected. A fuel injection control device (30) applied to a fuel injection system comprising a fuel pressure sensor (20),
An in-injection sensor waveform detection means for detecting an in-injection sensor waveform Wi based on an output of the fuel pressure sensor corresponding to the predetermined cylinder when injection is performed in the predetermined cylinder in a steady operation state of the engine. When,
The non-injection sensor waveform Wa is detected based on the output of the fuel pressure sensor corresponding to the predetermined cylinder when injection is performed in a cylinder different from the predetermined cylinder in the steady operation state of the engine. A non-injection sensor waveform detecting means,
Pressure fluctuation caused by injection in the predetermined cylinder by subtracting the non-injection sensor waveform detected by the non-injection sensor waveform from the injection sensor waveform detected by the injection sensor waveform detection means And a fuel injection waveform extracting means for extracting a fuel injection waveform W representing the fuel injection control device. When the injection timing of the predetermined cylinder is stopped at the injection timing of the predetermined cylinder in the steady operation state of the engine, when the pumping timing by the fuel pump and the injection timing by the fuel injection valve do not overlap, the predetermined cylinder An injection stop sensor waveform detection means for detecting an injection stop sensor waveform Wb based on the output of the fuel pressure sensor corresponding to
The injection time waveform extracting means includes the non-injection sensor waveform detected by the non-injection sensor waveform detection means and the injection stop time detected by the injection stop sensor waveform detection means from the injection sensor waveform. The fuel injection control device according to claim 1, wherein a sensor waveform is subtracted. The phase of the non-injection sensor waveform detected by the non-injection sensor waveform detection means is advanced according to the length of the fuel passage between the predetermined cylinder and the cylinder in which injection is performed. An advance correction means for correcting
The injection waveform extraction means includes the injection stop sensor waveform detected by the injection stop sensor waveform detection means and the non-injection sensor waveform corrected by the advance correction means from the injection sensor waveform. The fuel injection control device according to claim 2, wherein

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