JP6090112B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that supplies fuel discharged from a high-pressure pump driven by the internal combustion engine to a fuel injection valve of each cylinder.

  As a technique for correcting injection amount variation (cylinder air-fuel ratio variation) between cylinders of an internal combustion engine, for example, there is one described in Patent Document 1 (Japanese Patent Laid-Open No. 2010-43614). This is based on the output of the fuel pressure sensor that detects the fuel pressure (fuel pressure), and calculates the amount of fuel pressure drop that accompanies the fuel injection of the fuel injector for each cylinder as information on the variation in injection amount. By correcting the injection pulse width of the fuel injection valve of each cylinder based on the above, variation in the injection amount of the fuel injection valve of each cylinder is corrected.

  However, in a system that supplies fuel discharged from a high-pressure pump driven by an internal combustion engine to a fuel injection valve of each cylinder, the injection period of the fuel injection valve and the discharge period of the high-pressure pump may vary depending on the operating region of the internal combustion engine. May overlap. In the operation region where the injection period of the fuel injection valve and the discharge period of the high pressure pump overlap, when calculating the fuel pressure drop due to the fuel injection of the fuel injection valve based on the output of the fuel pressure sensor, the fuel discharge of the high pressure pump Under the influence of the increase in fuel pressure, it becomes difficult to accurately calculate the amount of decrease in fuel pressure accompanying the fuel injection of the fuel injection valve.

  Therefore, in Patent Document 1, the amount of fuel pressure drop accompanying fuel injection of the fuel injection valve is calculated based on the fuel pressure detected by the fuel pressure sensor during the non-discharge period of the high-pressure pump. In other words, when the fuel injection valve injection period and the high-pressure pump discharge period are in the operating region, the fuel pressure drop accompanying the fuel injection of the fuel injection valve is calculated based on the output of the fuel pressure sensor.

JP 2010-43614 A

  The variation in the injection amount of the fuel injection valve of each cylinder is not uniform with respect to the injection amount of the fuel injection valve, and if the injection amount of the fuel injection valve changes according to the operating region of the internal combustion engine, The injection amount variation also changes. For this reason, it is preferable to correct the injection amount variation of the fuel injection valve of each cylinder not only in a specific operation region but also in a wide operation region.

  However, in the technique of the above-mentioned Patent Document 1, only in the operation region where the injection period of the fuel injection valve and the discharge period of the high pressure pump do not overlap, only the amount of fuel pressure drop accompanying the fuel injection of the fuel injection valve is calculated. In the operation region (injection / discharge overlap region) where the injection period of the fuel injection valve and the discharge period of the high-pressure pump overlap, it is possible to calculate the fuel pressure drop amount (information on the injection amount variation) accompanying the fuel injection of the fuel injection valve. Can not. For this reason, in the injection discharge overlapping region, there is a drawback that the injection amount variation of the fuel injection valve of each cylinder cannot be corrected with high accuracy, and the region where the injection amount variation between cylinders can be corrected with high accuracy is limited. .

  Accordingly, the problem to be solved by the present invention is to provide a control device for an internal combustion engine that can expand the region where the variation in the injection amount between the cylinders can be accurately corrected.

  In order to solve the above problems, the invention according to claim 1 is directed to a fuel injection valve (31) for each cylinder through which fuel discharged from a high pressure pump (14) driven by an internal combustion engine passes through a high pressure fuel passage (29, 30). ) And a fuel pressure sensor (32) for detecting a fuel pressure (hereinafter referred to as “fuel pressure”) in the high pressure fuel passages (29, 30), and each output based on the output of the fuel pressure sensor (32). An injection amount variation correction for calculating a fuel pressure drop amount due to fuel injection of the fuel injection valve (31) for each cylinder and correcting a fuel injection amount variation of the fuel injection valve (31) of each cylinder based on the fuel pressure drop amount due to the fuel injection. In the control device for an internal combustion engine provided with the means (38), the injection amount variation correcting means (38) is an operation region (the operation period in which the injection period of the fuel injection valve (31) and the discharge period of the high-pressure pump (14) overlap. Less than" When morphisms discharge of overlapping area "), in which the injection quantity variation of the fuel injection valve of each cylinder (31) on the basis of the output of the fuel pressure sensor (32) and is corrected.

  In this way, even in the injection discharge overlap region, it is possible to accurately correct the injection amount variation of the fuel injection valve of each cylinder based on the output of the fuel pressure sensor (32), and to accurately correct the injection amount variation between the cylinders. The area that can be corrected can be enlarged.

  In this case, as in the second aspect, the injection amount variation correcting means (38) is configured so that the injection period start timing and the discharge period are determined for each cylinder based on the output of the fuel pressure sensor (32) in the injection discharge overlap region. The difference in fuel pressure before and after the period from the earlier start time to the later end time of the injection period and the later end time of the discharge period (hereinafter referred to as “injection / discharge period”) And the variation in the injection amount of the fuel injection valve (31) of each cylinder may be corrected based on the amount of change in fuel pressure due to the injection and discharge.

  According to the applicant's research, in the injection / discharge overlap region (the operation region where the injection period of the fuel injection valve and the discharge period of the high-pressure pump overlap), the OL amount between the injection period of the fuel injection valve and the discharge period of the high-pressure pump Regardless of the (overlap amount), it has been found that there is a correlation between the injection amount variation of the fuel injection valve and the fuel pressure change amount due to injection / discharge (difference in fuel pressure before and after the injection / discharge period) (see FIG. 4). ). That is, since the amount of change in fuel pressure due to injection / discharge changes in accordance with the variation in injection amount of the fuel injection valve, the amount of change in fuel pressure due to injection / discharge becomes information reflecting the variation in injection amount of the fuel injection valve.

  Focusing on this point, the present invention calculates the amount of change in fuel pressure (difference in fuel pressure before and after the injection / discharge period) for each cylinder based on the output of the fuel pressure sensor in the injection / discharge overlap region. It is calculated as variation information, and the variation in the injection amount of the fuel injection valve in each cylinder is corrected based on the amount of change in fuel pressure due to the injection and discharge in each cylinder. Thereby, it is possible to accurately correct the injection amount variation of the fuel injection valve of each cylinder even in the injection discharge overlapping region.

  As a result, in the operation region other than the injection discharge overlap region (operation region where the injection period of the fuel injection valve and the discharge period of the high pressure pump do not overlap), the fuel injection of each cylinder is performed based on the fuel pressure drop amount due to the fuel injection of each cylinder. It is possible to correct the injection amount variation of the valve with high accuracy and to accurately correct the injection amount variation of the fuel injection valve of each cylinder based on the fuel pressure change amount due to the injection discharge of each cylinder in the injection discharge overlapping region. Thus, it is possible to enlarge the region where the variation in the injection amount between the cylinders can be corrected with high accuracy.

FIG. 1 is a diagram showing a schematic configuration of a fuel supply system for a direct injection engine according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the amount of fuel pressure drop due to fuel injection. FIG. 3 is a diagram for explaining the amount of change in fuel pressure due to ejection and discharge. FIG. 4 is a diagram showing the relationship between the variation in the injection amount and the amount of change in the fuel pressure due to the injection and discharge. FIG. 5 is a flowchart showing the flow of processing of the injection amount variation correction routine.

Hereinafter, an embodiment embodying a mode for carrying out the present invention will be described.
First, a schematic configuration of a fuel supply system of a cylinder injection engine (internal combustion engine) will be described with reference to FIG.

  A low pressure pump 12 that pumps up the fuel is installed in the fuel tank 11 that stores the fuel. The low-pressure pump 12 is driven by an electric motor (not shown) that uses a battery (not shown) as a power source. The fuel discharged from the low pressure pump 12 is supplied to the high pressure pump 14 through the fuel pipe 13. A pressure regulator 15 is connected to the fuel pipe 13, and the pressure regulator 15 regulates the discharge pressure of the low-pressure pump 12 (fuel supply pressure to the high-pressure pump 14) to a predetermined pressure. Is returned to the fuel tank 11 by the fuel return pipe 16.

  The high-pressure pump 14 is a piston pump that sucks / discharges fuel by reciprocating a piston 19 (plunger) in a cylindrical pump chamber 18. The piston 19 is connected to a camshaft 20 of an engine (for example, a four-cylinder engine). It is driven by the rotational movement of the fitted cam 21 (for example, a four mountain cam having four cam mountains).

  A fuel pressure control valve 23 is provided on the suction port 22 side of the high-pressure pump 14. The fuel pressure control valve 23 is a normally open type electromagnetic valve, and includes a valve body 24 that opens and closes the suction port 22, a spring 25 that urges the valve body 24 in the valve opening direction, and a valve body 24 in the valve closing direction. And a solenoid 26 that is electromagnetically driven.

  During the intake stroke of the high-pressure pump 14 (when the piston 19 is lowered), the valve body 24 of the fuel pressure control valve 23 is opened and fuel is sucked into the pump chamber 18, and the discharge stroke of the high-pressure pump 14 (when the piston 19 is raised). , The energization of the solenoid 26 of the fuel pressure control valve 23 is controlled so that the valve body 24 of the fuel pressure control valve 23 is closed and the fuel in the pump chamber 18 is discharged. At that time, the energization start timing of the fuel pressure control valve 23 (solenoid 26) is controlled to set the closing period of the fuel pressure control valve 23 (the crank angle section in the closed state from the valve closing start timing to the top dead center of the piston 19). By controlling, the discharge amount of the high-pressure pump 14 is controlled to control the fuel pressure (fuel pressure). The energization start timing of the fuel pressure control valve 23 is set by a crank angle from a predetermined reference crank angle position (for example, a crank angle position corresponding to the top dead center of the piston 19).

  For example, when the fuel pressure is increased, the energization start timing of the fuel pressure control valve 23 is advanced to advance the valve closing start timing of the fuel pressure control valve 23, thereby extending the valve closing period of the fuel pressure control valve 23 and increasing the pressure. The discharge amount of the pump 14 is increased. Conversely, when the fuel pressure is decreased, the closing period of the fuel pressure control valve 23 is shortened by delaying the energization start timing of the fuel pressure control valve 23 and delaying the closing start timing of the fuel pressure control valve 23. The discharge amount of the high-pressure pump 14 is reduced.

  On the other hand, a check valve 28 for preventing the backflow of discharged fuel is provided on the discharge port 27 side of the high-pressure pump 14. The fuel discharged from the high-pressure pump 14 is sent to the delivery pipe 30 through the high-pressure fuel pipe 29, and the high-pressure fuel is distributed from the delivery pipe 30 to the fuel injection valve 31 attached to each cylinder of the engine. The delivery pipe 30 (or the high-pressure fuel pipe 29) is provided with a fuel pressure sensor 32 that detects a fuel pressure (fuel pressure) in a high-pressure fuel passage such as the high-pressure fuel pipe 29 or the delivery pipe 30. The delivery pipe 30 is provided with a relief valve 33, and a discharge port of the relief valve 33 is connected to the fuel tank 11 (or the low-pressure side fuel pipe 13) via a relief pipe 34.

  In this embodiment, a fuel injection valve 31 is provided in each cylinder of a four-cylinder engine, and a four-crest cam having four cam crests is used as the cam 21 for driving the high-pressure pump 14. As a result, every time the camshaft 20 of the engine rotates once (that is, the crankshaft rotates twice), fuel injection of the fuel injection valve 31 is performed four times and fuel discharge of the high-pressure pump 14 is performed four times.

  Further, the engine is provided with an air flow meter 36 for detecting the amount of intake air and a crank angle sensor 37 for outputting a pulse signal at every predetermined crank angle in synchronization with rotation of a crankshaft (not shown). Based on the output signal of the crank angle sensor 37, the crank angle and the engine speed are detected.

  Outputs of the various sensors described above are input to an electronic control unit (hereinafter referred to as “ECU”) 38. The ECU 38 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount and the ignition timing are determined according to the engine operating state. The throttle opening (intake air amount) and the like are controlled.

  At that time, the ECU 38 calculates a target fuel pressure from a map or the like according to the engine operating state (for example, engine speed, engine load, etc.), and matches the actual fuel pressure in the high-pressure fuel passage detected by the fuel pressure sensor 32 with the target fuel pressure. As described above, the fuel pressure feedback control is executed to feedback control the discharge amount of the high-pressure pump 14 (energization timing of the fuel pressure control valve 23).

  Further, the ECU 38 calculates a required injection amount according to the engine operating state (for example, engine speed, engine load, etc.), and according to the required injection amount and the actual fuel pressure (or target fuel pressure) detected by the fuel pressure sensor 32. Then, the injection time (injection pulse width) of the fuel injection valve 31 is calculated, and the fuel injection valve 31 is driven to open during this injection time to inject fuel for the required injection amount.

  Further, the ECU 38 is based on the output of an exhaust gas sensor (for example, an air-fuel ratio sensor or an oxygen sensor) that detects the air-fuel ratio or rich / lean of the engine exhaust gas when a predetermined air-fuel ratio feedback control execution condition is satisfied. Then, the air-fuel ratio feedback correction amount is calculated so that the air-fuel ratio of the exhaust gas matches the target air-fuel ratio, and air-fuel ratio feedback control for correcting the required injection amount using this air-fuel ratio feedback correction amount is executed.

  By the way, even if the injection time (injection pulse width) of the fuel injection valve 31 of each cylinder is the same, the fuel injection valve 31 of each cylinder depends on individual differences (manufacturing variation) of the fuel injection valves 31 of each cylinder, changes over time, and the like. There may be variations in the injection amount.

  Therefore, the ECU 38 calculates the fuel pressure drop amount due to the fuel injection of the fuel injection valve 31 for each cylinder based on the output of the fuel pressure sensor 32 as information on the injection amount variation, and based on the fuel pressure drop amount due to the fuel injection of each cylinder. Variations in the injection amount of the fuel injection valve 31 of each cylinder are corrected.

  However, in a system that supplies fuel discharged from the high-pressure pump 14 driven by the engine to the fuel injection valve 31 of each cylinder, the injection period of the fuel injection valve 31 and the discharge period of the high-pressure pump 14 depend on the engine operating region. And may overlap. In an operation region where the injection period of the fuel injection valve 31 and the discharge period of the high-pressure pump 14 overlap (hereinafter referred to as “injection / discharge overlap region”), the fuel pressure drop due to fuel injection of the fuel injection valve 31 based on the output of the fuel pressure sensor 32. When calculating the amount, it is difficult to accurately calculate the amount of fuel pressure decrease due to fuel injection of the fuel injection valve 31 due to the influence of fuel pressure increase due to fuel discharge of the high-pressure pump 14.

  Therefore, in this embodiment, the ECU 38 executes an injection amount variation correction routine, which will be described later, with reference to the output of the fuel pressure sensor 32 for each cylinder based on the output of the fuel pressure sensor 32. The amount of fuel pressure drop due to fuel injection of the valve 31 (see FIG. 2) is calculated, and the injection amount variation of the fuel injection valve 31 of each cylinder is corrected based on the amount of fuel pressure drop due to fuel injection of each cylinder. On the other hand, in the injection / discharge overlap region, the end of the injection period and the end of the discharge period are determined from the earlier of the start time of the injection period and the start time of the discharge period for each cylinder based on the output of the fuel pressure sensor 32. The difference in fuel pressure before and after the later period (hereinafter referred to as “injection / discharge period”) is calculated as the amount of change in fuel pressure by injection / discharge (see FIG. 3), and based on the amount of change in fuel pressure by injection / discharge of each cylinder. Variations in the injection amount of the fuel injection valve 31 of each cylinder are corrected.

  As shown in FIG. 4, according to the study by the present applicant, in the injection / discharge overlapping region (the operation region where the injection period of the fuel injection valve 31 and the discharge period of the high-pressure pump 14 overlap), the injection period of the fuel injection valve 31. Regardless of the OL amount (overlap amount) between the high pressure pump 14 and the discharge period of the high-pressure pump 14, between the injection amount variation of the fuel injection valve 31 and the fuel pressure change amount due to the injection discharge (difference in fuel pressure before and after the injection discharge period). It was found that there was a correlation. That is, the amount of change in fuel pressure due to injection / discharge changes according to the variation in injection amount of the fuel injection valve 31, so the amount of fuel pressure change due to injection / discharge becomes information reflecting the variation in injection amount of the fuel injection valve 31.

  Therefore, in the overlapping region of injection and discharge, the amount of change in fuel pressure due to injection and discharge is calculated as information on the variation in injection amount for each cylinder based on the output of the fuel pressure sensor 32, and the amount of change in fuel pressure due to injection and discharge in each cylinder is calculated. If the variation in the injection amount of the fuel injection valve 31 in each cylinder is corrected, the variation in the injection amount of the fuel injection valve 31 in each cylinder can be accurately corrected even in the injection discharge overlap region.

  Further, in the present embodiment, in order to compensate for the influence of the variation in the discharge amount of each fuel discharge of the high-pressure pump 14, the high-pressure pump 14 of the high-pressure pump 14 is based on the output of the fuel pressure sensor 32 in the operation region other than the injection discharge overlap region. The amount of increase in fuel pressure due to fuel discharge is calculated for each fuel discharge, and the variation in discharge amount of each fuel discharge of the high-pressure pump 14 is learned based on the amount of fuel pressure increase due to fuel discharge. Then, in the injection / discharge overlap region, the fuel pressure change amount due to the injection / discharge of each cylinder is corrected using the discharge amount variation (learned value) of each fuel discharge, and the corrected fuel pressure change amount due to the injection / discharge of each cylinder is corrected. Based on this, the injection amount variation of the fuel injection valve 31 of each cylinder is corrected.

Hereinafter, the processing content of the injection amount variation correction routine of FIG. 5 executed by the ECU 38 in this embodiment will be described.
The injection amount variation correction routine shown in FIG. 5 is repeatedly executed at a predetermined period during the power-on period of the ECU 38 (while the ignition switch is on), and plays a role as an injection amount variation correction means in the claims.

  When this routine is started, first, in step 101, the injection / discharge overlap region (the injection period of the fuel injection valve 31 and the discharge of the high-pressure pump 14) is determined based on the control amount of the fuel injection valve 31 and the control amount of the high-pressure pump 14. It is determined whether or not the operation region overlaps with the period. For example, an injection start timing and an end timing are obtained from the injection timing and injection time of the fuel injection valve 31, and it is determined whether or not there is an overlap with the discharge timing of the high-pressure pump 14 obtained by the following method. First, the top dead center timing of the piston 19 of the high-pressure pump 14 is obtained from the phase of the cam 21 that drives the piston 19 of the high-pressure pump 14. Next, the energization start timing of the fuel pressure control valve 23 is obtained based on the output of the fuel pressure sensor 32, the target fuel pressure, and the like. The discharge timing of the high-pressure pump 14 is obtained based on the energization start timing of the fuel pressure control valve 23 and the top dead center timing of the piston 19.

  If it is determined in step 101 that there is no injection / discharge overlap region, that is, in an operation region other than the injection / discharge overlap region (an operation region where the injection period of the fuel injection valve 31 and the discharge period of the high-pressure pump 14 do not overlap). If it is determined that there is, the routine proceeds to step 102, where the fuel pressure drop due to the fuel injection of the fuel injection valve 31 is calculated for each cylinder based on the output of the fuel pressure sensor 32. In this case, for example, for each cylinder, the fuel pressure detected for a predetermined period immediately before the start of fuel injection (for example, an average value of a plurality of detected values) and the fuel pressure detected for a predetermined period immediately after the end of fuel injection (for example, a plurality of times) The difference between the detected value and the average value is calculated as the amount of fuel pressure drop due to fuel injection.

  Thereafter, the process proceeds to step 103, where the average value of the fuel pressure drop due to the fuel injection of all cylinders is calculated, and the deviation between the fuel pressure drop due to the fuel injection and the average value is calculated as the injection amount variation for each cylinder. Thus, the injection amount variation of the fuel injection valve 31 of each cylinder is calculated.

  Thereafter, the routine proceeds to step 104 where the fuel pressure increase amount due to fuel discharge is calculated for each fuel discharge of the high-pressure pump 14 based on the output of the fuel pressure sensor 32. In this case, for example, for each fuel discharge of the high-pressure pump 14, the fuel pressure (for example, an average value of a plurality of detection values) detected in a predetermined period immediately after the end of fuel discharge and a predetermined period immediately before the start of fuel discharge are detected. A difference from the fuel pressure (for example, an average value of a plurality of detection values) is calculated as an increase in fuel pressure due to fuel discharge.

  Thereafter, the process proceeds to step 105, and for each fuel discharge of the high pressure pump 14, the difference between the fuel pressure increase amount due to the fuel discharge and the reference value is calculated as a discharge amount variation, thereby discharging each fuel discharge of the high pressure pump 14. The amount variation is calculated. Then, the discharge amount variation of each fuel discharge of the high-pressure pump 14 is stored in a memory such as the ECU 38 to learn the discharge amount variation of each fuel discharge of the high-pressure pump 14. The processing of these steps 104 and 105 serves as a discharge amount variation learning means in the claims.

  Thereafter, the process proceeds to step 109, and the injection amount variation correction amount is calculated for each cylinder so that the variation in the injection amount of the fuel injection valve 31 is reduced. The ECU 38 corrects the required injection amount for each cylinder by using the injection amount variation correction amount, thereby correcting the injection amount of the fuel injection valve 31 of each cylinder for each cylinder. The injection amount variation of 31 is reduced (the injection amount variation between cylinders is reduced).

  On the other hand, if it is determined in step 101 that the region is an overlapping region of injection and discharge, the process proceeds to step 106, and the fuel pressure change amount due to injection and discharge for each cylinder based on the output of the fuel pressure sensor 32 (before the start of the injection and discharge period). And the difference between the fuel pressure after the end of the injection and discharge period).

  As shown in FIG. 3A, when the rear side portion of the injection period overlaps with the front side portion of the discharge period, that is, when the injection discharge period is from the start time of the injection period to the end time of the discharge period. Calculates the amount of change in fuel pressure due to injection and discharge as follows. For each cylinder, the fuel pressure detected for a predetermined period immediately before the start of fuel injection of the fuel injection valve 31 (for example, the average value of a plurality of detected values) and the fuel pressure detected for a predetermined period immediately after the end of fuel discharge of the high-pressure pump 14 A difference from (for example, an average value of a plurality of detection values) is calculated as a fuel pressure change amount due to injection and discharge.

  As shown in FIG. 3B, when the rear side of the discharge period overlaps with the front side of the injection period, that is, when the period from the start time of the discharge period to the end time of the injection period becomes the injection discharge period. Calculates the amount of change in fuel pressure due to injection and discharge as follows. For each cylinder, the fuel pressure detected for a predetermined period immediately before the start of fuel discharge of the high-pressure pump 14 (for example, the average value of a plurality of detected values) and the fuel pressure detected for a predetermined period immediately after the end of fuel injection of the fuel injection valve 31 A difference from (for example, an average value of a plurality of detection values) is calculated as a fuel pressure change amount due to injection and discharge.

  As shown in FIG. 3C, when the injection periods overlap so as to encompass the discharge period (when the entire discharge period overlaps within the injection period), that is, injection from the start time of the injection period When the period until the end of the period is the injection discharge period, the amount of change in fuel pressure due to injection discharge is calculated as follows. For each cylinder, the fuel pressure detected during a predetermined period immediately before the start of fuel injection of the fuel injection valve 31 (for example, the average value of a plurality of detected values) and the predetermined period immediately after the end of fuel injection of the fuel injection valve 31 are detected. A difference from the fuel pressure (for example, an average value of a plurality of detection values) is calculated as a fuel pressure change amount due to injection / discharge.

  As shown in FIG. 3D, when the discharge periods overlap so as to encompass the injection period (when the entire injection period overlaps within the discharge period), that is, discharge from the start time of the discharge period. When the period until the end of the period is the injection discharge period, the amount of change in fuel pressure due to injection discharge is calculated as follows. For each cylinder, the fuel pressure detected for a predetermined period immediately before the start of fuel discharge of the high-pressure pump 14 (for example, an average value of a plurality of detected values) and the fuel pressure detected for a predetermined period immediately after the end of fuel discharge of the high-pressure pump 14 ( For example, a difference from an average value of a plurality of detection values) is calculated as a fuel pressure change amount due to injection and discharge.

  Thereafter, the process proceeds to step 107, and the fuel pressure change amount due to the injection / discharge of each cylinder is corrected using the discharge amount variation (learning value) of each fuel discharge of the high-pressure pump 14. In this case, for example, for each cylinder, the variation in the fuel pressure due to the injection / discharge of each cylinder is corrected by adding the variation in the fuel discharge amount corresponding to the fuel injection in the corresponding cylinder to the amount of the fuel pressure variation due to the injection / discharge. .

  Thereafter, the routine proceeds to step 108, where the average value of the fuel pressure change amount due to the injection / discharge of all cylinders is calculated using the corrected fuel pressure change amount due to the injection / discharge of each cylinder, and the fuel pressure due to the injection / discharge for each cylinder. By calculating the deviation between the change amount and the average value as the injection amount variation, the injection amount variation of the fuel injection valve 31 of each cylinder is calculated.

  Thereafter, the process proceeds to step 109, and the injection amount variation correction amount is calculated for each cylinder so that the variation in the injection amount of the fuel injection valve 31 is reduced. The ECU 38 corrects the required injection amount for each cylinder by using the injection amount variation correction amount, thereby correcting the injection amount of the fuel injection valve 31 of each cylinder for each cylinder. The injection amount variation of 31 is reduced (the injection amount variation between cylinders is reduced).

  In the present embodiment described above, in the operation region other than the injection discharge overlap region, the fuel pressure drop amount due to the fuel injection of the fuel injection valve 31 is calculated as information on the injection amount variation for each cylinder based on the output of the fuel pressure sensor 32. Then, the injection amount variation of the fuel injection valve 31 of each cylinder is corrected based on the amount of fuel pressure drop due to the fuel injection of each cylinder. On the other hand, in the overlapping region of injection and discharge, the amount of change in fuel pressure due to injection and discharge (difference in fuel pressure before and after the injection and discharge period) is calculated for each cylinder based on the output of the fuel pressure sensor 32 as information on the variation in injection amount. The variation in the injection amount of the fuel injection valve 31 of each cylinder is corrected based on the amount of change in the fuel pressure due to the injection and discharge.

  Accordingly, in the operation region other than the injection / discharge overlapping region, the injection amount variation of the fuel injection valve 31 of each cylinder can be accurately corrected based on the fuel pressure drop amount due to the fuel injection of each cylinder, and the injection / discharge overlapping region. Then, it is possible to accurately correct the injection amount variation of the fuel injection valve 31 of each cylinder based on the amount of change in the fuel pressure due to the injection / discharge of each cylinder, and to enlarge the region where the injection amount variation among the cylinders can be accurately corrected. Can do.

  Further, in this embodiment, the variation in the discharge amount of each fuel discharge of the high-pressure pump 14 is learned, and in the injection discharge overlap region, the variation in the discharge amount of each fuel discharge (learned value) is used for the injection discharge of each cylinder. The fuel pressure change amount is corrected, and the variation in the injection amount of the fuel injection valve 31 of each cylinder is corrected based on the corrected fuel pressure change amount due to the injection and discharge of each cylinder. As a result, it is possible to compensate for fluctuations in the amount of change in the fuel pressure due to the influence of the variation in the discharge amount, and it is possible to improve the correction accuracy of the variation in the injection amount of the fuel injection valve 31 of each cylinder.

  In addition, in this embodiment, in the operation region other than the injection discharge overlap region, the fuel pressure increase amount due to the fuel discharge is calculated for each fuel discharge of the high pressure pump 14 based on the output of the fuel pressure sensor 32, and the fuel discharge Based on the fuel pressure increase, the discharge amount variation of each fuel discharge of the high-pressure pump 14 is learned. Thereby, the fuel pressure increase amount due to the fuel discharge of the high-pressure pump 14 can be accurately calculated without being influenced by the fuel pressure drop due to the fuel injection of the fuel injection valve 31, and the high pressure is based on the fuel pressure increase amount due to the fuel discharge. It is possible to learn the discharge amount variation of the pump 14 with high accuracy.

  In the above embodiment, the fuel pressure detected during a predetermined period (for example, an average value of a plurality of detected values) is used when calculating the amount of change in fuel pressure due to injection / discharge. You may make it use the value which processed the output of the sensor 32 using the filter which removes a specific frequency band. Specifically, the difference between the value obtained by filtering the output of the fuel pressure sensor 32 before the start of the injection / discharge period and the value obtained by filtering the output of the fuel pressure sensor 32 after the end of the injection / discharge period is the amount of change in fuel pressure due to the injection / discharge. You may make it calculate as.

  In the above embodiment, the fuel pressure change amount due to the injection / discharge of each cylinder is corrected using the discharge amount variation (learning value) of each fuel discharge of the high-pressure pump 14 in the injection / discharge overlapping region, The variation in the injection amount of the fuel injection valve 31 of each cylinder is calculated based on the amount of change in the fuel pressure due to the injection / discharge of the cylinder. However, the present invention is not limited to this, for example, based on the amount of change in the fuel pressure due to the injection / discharge of each cylinder. After calculating the injection amount variation of the fuel injection valve 31 of each cylinder, the injection amount variation of the fuel injection valve 31 of each cylinder is corrected using the discharge amount variation (learning value) of each fuel discharge of the high-pressure pump 14. May be.

  Further, in the above embodiment, the injection amount variation of the fuel injection valve 31 of each cylinder is corrected based on the fuel pressure change amount and the discharge amount variation due to the injection discharge in the injection discharge overlapping region. For example, when the discharge amount variation of each fuel discharge of the high-pressure pump 14 is small, the injection of the fuel injection valve 31 of each cylinder is based only on the fuel pressure change amount by the injection discharge without using the discharge amount variation. The amount variation may be corrected.

  In the above embodiment, the fuel pressure difference before and after the injection / discharge period is calculated as the fuel pressure change amount by the injection / discharge in the injection / discharge overlapping region. However, the present invention is not limited to this. The fuel pressure is integrated in (or the period from the start to the end of the injection / discharge period), and the integrated value is used as information on the amount of change in fuel pressure by injection / discharge (a parameter for evaluating the amount of change in fuel pressure by injection / discharge). Also good.

  Further, in the above embodiment, when the injection discharge overlap region, the deviation between the fuel pressure change amount due to the injection discharge of each cylinder and the average value is calculated as the injection amount variation. After the fuel pressure change amount due to the injection discharge of each cylinder is converted into the injection amount increase / decrease rate (or injection amount increase / decrease amount), the deviation between the injection amount increase / decrease rate (or injection amount increase / decrease amount) and the average value of each cylinder varies with the injection amount. It may be calculated as:

  Further, in the above embodiment, the deviation between the fuel pressure drop amount and the average value due to the fuel injection of each cylinder is calculated as the injection amount variation in the region other than the injection discharge overlapping region. However, the present invention is not limited to this. For example, after converting the fuel pressure drop amount due to fuel injection in each cylinder into the injection amount increase / decrease rate (or injection amount increase / decrease amount), the deviation between the injection amount increase / decrease rate (or injection amount increase / decrease amount) and the average value of each cylinder is calculated. You may make it calculate as injection amount dispersion | variation.

  Further, in the above embodiment, the deviation between the fuel pressure increase amount due to fuel discharge for each fuel discharge and the reference value is calculated as the discharge amount variation. However, the present invention is not limited to this. For example, the fuel for each fuel discharge After the fuel pressure increase due to discharge is converted into the discharge amount increase / decrease rate (or discharge amount increase / decrease amount), the deviation between the discharge amount increase / decrease rate (or discharge amount increase / decrease amount) and the average value for each fuel discharge is calculated as the discharge amount variation. You may make it do.

  Further, the application range of the present invention is not limited to a four-cylinder engine, and the present invention may be applied to an engine having three or less cylinders or an engine having five or more cylinders. Further, the cam 21 for driving the piston 19 of the high-pressure pump 14 is not limited to the configuration using the four cams having four cam peaks, and for example, the configuration using the three cams having three cam peaks or 2 It is good also as a structure using the two mountain cam which has one cam mountain.

  In other words, in the above-described embodiment, in a four-cylinder engine, every time the camshaft rotates once (the crankshaft rotates twice), the fuel injection valve performs fuel injection four times and the high-pressure pump discharges fuel four times. Although the present invention is applied, the present invention is not limited to this. For example, in a six-cylinder engine, every time the camshaft rotates once (the crankshaft rotates twice), fuel injection of the fuel injection valve is performed six times and the fuel of the high-pressure pump A system in which the discharge is performed three times or a system in which the fuel injection valve performs fuel injection eight times and the high-pressure pump performs fuel discharge four times each time the camshaft rotates once (crankshaft rotates twice) in an 8-cylinder engine. The present invention may be applied to.

  In addition, the present invention can be implemented with various modifications without departing from the gist, such as appropriately changing the configuration of the high-pressure pump and the configuration of the fuel supply system.

  DESCRIPTION OF SYMBOLS 14 ... High pressure pump, 29 ... High pressure fuel piping (high pressure fuel passage), 30 ... Delivery pipe (high pressure fuel passage), 31 ... Fuel injection valve, 32 ... Fuel pressure sensor, 38 ... ECU (Injection amount variation correction means, Discharge amount variation) Learning means)

Claims (8)

The present invention is applied to a system for supplying fuel discharged from a high pressure pump (14) driven by an internal combustion engine to a fuel injection valve (31) of each cylinder through a high pressure fuel passage (29, 30). 30) a fuel pressure sensor (32) for detecting the fuel pressure in the fuel (hereinafter referred to as "fuel pressure"), and fuel injection of the fuel injection valve (31) for each cylinder based on the output of the fuel pressure sensor (32). Control of an internal combustion engine comprising an injection amount variation correcting means (38) for calculating a fuel pressure decrease amount and correcting an injection amount variation of the fuel injection valve (31) of each cylinder based on the fuel pressure decrease amount due to the fuel injection. In the device
The injection amount variation correcting means (38) is in an operation region where the injection period of the fuel injection valve (31) and the discharge period of the high-pressure pump (14) overlap (hereinafter referred to as “injection / discharge overlap region”). A control apparatus for an internal combustion engine, wherein the variation in the injection amount of the fuel injection valve (31) of each cylinder is corrected based on the output of the fuel pressure sensor (32).   The injection amount variation correcting means (38) determines the start timing of the injection period and the start time of the discharge period for each cylinder based on the output of the fuel pressure sensor (32) in the injection discharge overlap region. The difference in fuel pressure before and after the period from the earliest to the later of the end time of the injection period and the end time of the discharge period (hereinafter referred to as “injection / discharge period”) is calculated as the amount of change in fuel pressure due to injection / discharge. The control device for an internal combustion engine according to claim 1, wherein the variation in the injection amount of the fuel injection valve (31) of each cylinder is corrected based on the amount of change in fuel pressure due to the injection discharge. Discharge amount variation learning means (38) for learning the discharge amount variation of each fuel discharge of the high-pressure pump (14),
The injection amount variation correction means (38) varies the injection amount of the fuel injection valve (31) of each cylinder based on the fuel pressure change amount due to the injection discharge and the variation in the discharge amount in the injection discharge overlap region. The control apparatus for an internal combustion engine according to claim 2, wherein:   The discharge amount variation learning means (38) performs fuel discharge for each fuel discharge of the high-pressure pump (14) based on the output of the fuel pressure sensor (32) in an operation region other than the injection discharge overlap region. The control apparatus for an internal combustion engine according to claim 3, wherein a fuel pressure increase amount is calculated, and a variation in the discharge amount of each fuel discharge of the high-pressure pump (14) is learned based on the fuel pressure increase amount due to the fuel discharge. .   The injection amount variation correcting means (38) is configured to output an average value of the output of the fuel pressure sensor (32) in a predetermined period before the start of the injection / discharge period and after the end of the injection / discharge period in the injection / discharge overlapping region. The control device for an internal combustion engine according to any one of claims 2 to 4, wherein a difference from an average value of the output of the fuel pressure sensor (32) during a predetermined period is calculated as a fuel pressure change amount due to the injection and discharge. .   The injection amount variation correcting means (38) uses a filter to process the output of the fuel pressure sensor (32) before the start of the injection / discharge period and after the end of the injection / discharge period in the injection / discharge overlapping region. The control device for an internal combustion engine according to any one of claims 2 to 4, wherein a fuel pressure change amount due to the injection and discharge is calculated based on the obtained value.   The injection amount variation correcting means (38) determines whether or not the injection discharge overlapping region is based on a control amount of the fuel injection valve (31) and a control amount of the high pressure pump (14). The control apparatus for an internal combustion engine according to any one of claims 1 to 6.   The injection amount variation correcting means (38) includes an injection timing and an injection period as control amounts of the fuel injection valve (31), a target fuel pressure as a control amount of the high pressure pump (14), and the high pressure pump (14). 8. The control apparatus for an internal combustion engine according to claim 7, wherein it is determined whether or not the injection discharge overlapping region is based on a phase of a cam (21) for driving the piston (19) of the engine.

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