JP2017160916A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous correction of an injection quantities of respective cylinders, in a system for correcting variations in injection quantities of fuel injection valves in the respective cylinders of an engine.SOLUTION: Whether execution conditions for correction control of variations in injection quantities are established or not are determined depending on whether all of various conditions such that an engine is in a normal operation, injection quantities of fuel injection valves 31 are within a prescribed range, and fuel pressure is within a prescribed range, are satisfied. When determining that the execution conditions for the correction control of the variations in the injection quantities are established, fuel pressure drop amounts due to fuel injection of the fuel injection valves 31 for each of respective cylinders are calculated on the basis of output of a fuel pressure sensor 32, and the correction control of the variations in the injection quantities for correcting the variations in the injection quantities of the fuel injection valves 31 of the respective cylinders are executed on the basis of fuel pressure drop amounts due to the fuel injection of the respective cylinders. Thus, the fuel pressure drop amounts due to the fuel injection of the respective cylinders are accurately calculated and the variations in the injection quantities of the respective cylinders are exactly corrected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine that corrects variation in the injection amount of the fuel injection valve of each cylinder.

  In a system for supplying fuel discharged from a high-pressure pump to a fuel injection valve of each cylinder of an internal combustion engine, as a technique for correcting injection amount variation between cylinders of the internal combustion engine (air-fuel ratio variation between cylinders), for example, Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2010-43614). This calculates the amount of fuel pressure drop accompanying fuel injection of the fuel injection valve for each cylinder based on the output of the fuel pressure sensor that detects the fuel pressure (fuel pressure) as information on the variation in the injection amount. By correcting the injection pulse width of the fuel injection valve of each cylinder based on the accompanying fuel pressure drop amount, the variation in the injection amount of the fuel injection valve of each cylinder is corrected (reduced).

JP 2010-43614 A

  By the way, when the required injection amount changes according to the change in the operating state of the internal combustion engine during transient operation such as acceleration or deceleration of the internal combustion engine, the injection amount of the fuel injection valve of each cylinder changes in order of injection. Accordingly, the fuel pressure drop amount due to the fuel injection of each cylinder also changes in order in accordance with the injection. In such a case, the amount of fuel pressure drop due to fuel injection changes (increases or decreases) under the influence of the change in injection amount due to changes in the operating state of the internal combustion engine. The information does not accurately reflect the variation in the injection amount of each cylinder. For this reason, when performing the injection amount variation correction control for correcting the variation in the injection amount of the fuel injection valve of each cylinder based on the amount of fuel pressure drop due to the fuel injection of each cylinder during transient operation such as acceleration or deceleration of the internal combustion engine The variation in the injection amount of each cylinder cannot be corrected correctly, and the injection amount of each cylinder may be erroneously corrected.

  However, in the technique of Patent Document 1 described above, such a situation is not taken into consideration at all. Therefore, during the transient operation of the internal combustion engine, each cylinder is affected by the change in the injection amount due to the change in the operation state of the internal combustion engine. Despite the fact that the fuel pressure drop due to fuel injection does not accurately reflect the injection amount variation of each cylinder, the fuel injection valve variation of each cylinder based on the fuel pressure drop due to fuel injection of each cylinder There is a possibility that the injection amount variation correction control for correcting the injection amount is executed and the injection amount of each cylinder is erroneously corrected.

  Accordingly, the problem to be solved by the present invention is to provide a control device for an internal combustion engine that can prevent erroneous correction of the injection amount of each cylinder in a system that corrects variation in the injection amount of the fuel injection valve of each cylinder. There is.

  In order to solve the above-mentioned problem, the invention according to claim 1 supplies the fuel discharged from the high-pressure pump (14) to the fuel injection valve (31) of each cylinder of the internal combustion engine through the 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 passage (29, 30), and for each cylinder based on the output of the fuel pressure sensor (32). An injection amount variation correction control for calculating a fuel pressure decrease amount by fuel injection of the fuel injection valve (31) and correcting an injection amount variation of the fuel injection valve (31) of each cylinder based on the fuel pressure decrease amount by the fuel injection is executed. In the control apparatus for an internal combustion engine provided with the injection amount variation correcting means (38) for performing the injection amount variation correcting means (38), the injection amount variation correcting control is executed when the operating state of the internal combustion engine is in a steady state. Therefore, the injection amount variation correction means (38) performs the injection amount variation correction control on condition that the injection period of the fuel injection valve (31) and the discharge period of the high-pressure pump (14) do not overlap. It is a thing.

  During steady operation of the internal combustion engine (when the internal combustion engine is in a steady state), the fuel pressure drop due to fuel injection in each cylinder is not affected by the change in the injection amount due to the change in the operation state of the internal combustion engine. The information accurately reflects the variation in the injection amount of each cylinder. Therefore, during the steady operation of the internal combustion engine, if the injection amount variation correction control for correcting the variation in the injection amount of the fuel injection valve of each cylinder is executed based on the amount of fuel pressure drop due to the fuel injection of each cylinder, The variation in the injection amount can be corrected correctly, and erroneous correction of the injection amount of each cylinder can be prevented.

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 time chart for explaining a method of calculating the amount of fuel pressure drop due to fuel injection. FIG. 3 is a flowchart showing the flow of processing of the injection amount variation correction main routine. FIG. 4 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. In this way, the fuel pressure F / B control is executed to F / B control the discharge amount of the high-pressure pump 14 (energization timing of the fuel pressure control valve 23). Here, “F / B” means “feedback” (hereinafter the same).

  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 outputs 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 exhaust gas of the engine when a predetermined air-fuel ratio F / B control execution condition is satisfied. The main F / B correction amount is calculated so that the air-fuel ratio of the exhaust gas matches the target air-fuel ratio, and the air-fuel ratio F / B control for correcting the required injection amount using this main F / B correction amount is performed. Run.

  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, in this embodiment, the ECU 38 executes the routines for correcting the injection amount variation shown in FIGS. 3 and 4 to be described later, so that the fuel injection of the fuel injection valve 31 is performed for each cylinder based on the output of the fuel pressure sensor 32. The fuel pressure drop amount is calculated as the injection amount variation information, and the injection amount variation correction control for correcting the injection amount variation of the fuel injection valve 31 of each cylinder based on the fuel pressure drop amount due to the fuel injection of each cylinder is executed. ing.

  Specifically, as shown in FIG. 2, in the injection amount variation correction control, first, the fuel pressure is increased from the normal target fuel pressure (target fuel pressure according to the engine operating state) by the high-pressure pump 14 to the target fuel pressure for boosting. After the pressure has been increased to, the discharge of the high-pressure pump 14 is stopped for a predetermined period (for example, the period until the fuel pressure drops to the normal target fuel pressure). During this pump discharge stop period, every time fuel injection of the fuel injection valve 31 is executed, the process of calculating the fuel pressure drop ΔP is repeated to calculate the fuel pressure drop ΔP (#i) due to fuel injection of each cylinder. Here, #i is a cylinder number, and i = 1 to 4 in the case of a 4-cylinder engine.

  After that, the average value of the fuel pressure drop due to fuel injection in all cylinders is calculated, and the deviation between the fuel pressure drop due to fuel injection and the average value is calculated as the injection amount variation for each cylinder. The injection amount variation of the fuel injection valve 31 is calculated.

  Thereafter, the injection amount variation correction amount is calculated for each cylinder so that the injection amount variation of the fuel injection valve 31 is reduced, and the required injection amount is corrected for each cylinder using the injection amount variation correction amount. Thus, the injection pulse width (injection time) of the fuel injection valve 31 of each cylinder is corrected for each cylinder, and the injection amount variation of the fuel injection valve 31 of each cylinder is reduced (the injection amount variation between cylinders is reduced). To do).

  By the way, during the transient operation such as when the engine is accelerated or decelerated, if the required injection amount changes according to the change in the engine operating state, the injection amount of the fuel injection valve 31 of each cylinder changes in order of injection. Accordingly, the amount of fuel pressure drop due to fuel injection in each cylinder also changes in order of injection. In such a case, the fuel pressure drop amount due to fuel injection changes (increases or decreases) under the influence of the change in the injection amount due to changes in the engine operating state. This information does not accurately reflect the variation in the injection amount. For this reason, when performing an injection amount variation correction control for correcting variation in the injection amount of the fuel injection valve 31 of each cylinder based on the amount of fuel pressure drop due to fuel injection of each cylinder during transient operation such as acceleration or deceleration of the engine. The variation in the injection amount of each cylinder cannot be corrected correctly, and the injection amount of each cylinder may be erroneously corrected.

  Therefore, in this embodiment, each routine for correcting the injection amount variation in FIGS. 3 and 4 to be described later is executed by the ECU 38, so that each time the engine is in steady operation (when the engine is in a steady state), Injection amount variation correction control for correcting variation in the injection amount of the fuel injection valve 31 of each cylinder based on the amount of fuel pressure drop due to fuel injection of the cylinder is executed.

  During steady operation of the engine, the amount of fuel pressure drop due to fuel injection in each cylinder is information that accurately reflects variations in the injection amount of each cylinder without being affected by changes in the injection amount due to changes in engine operating conditions. Accordingly, if the injection amount variation correction control for correcting the variation in the injection amount of the fuel injection valve 31 of each cylinder is executed based on the amount of fuel pressure drop due to the fuel injection of each cylinder during steady operation of the engine, The variation in the injection amount can be corrected correctly, and erroneous correction of the injection amount of each cylinder can be prevented.

  By the way, when the injection amount variation correction control is performed, if the injection amount of the fuel injection valve 31 is small, the fuel pressure drop amount due to fuel injection becomes small. Therefore, the calculation error and resolution (LSB) included in the calculated value of the fuel pressure drop amount are reduced. The variation due to the above becomes relatively large, and the variation due to the injection amount variation becomes relatively small. For this reason, if the injection amount of the fuel injection valve 31 is too small, even if the fuel pressure drop amount due to the fuel injection of each cylinder is compared, the variation due to the variation in the injection amount is buried in the variation due to the calculation error or resolution. Therefore, there is a possibility that variation in the injection amount of each cylinder cannot be correctly determined.

  On the other hand, when the injection amount variation correction control is performed, if the injection amount of the fuel injection valve 31 is large, the amount of fuel pressure drop due to fuel injection increases. For this reason, if the injection amount of the fuel injection valve 31 is too large, the number of times of fuel injection is calculated during the pump discharge stop period after increasing the fuel pressure (the amount of fuel pressure drop due to fuel injection in each cylinder is calculated). Before the fuel injection pressure reaches the normal target fuel pressure (fuel pressure before pressure increase), the fuel pressure drop due to fuel injection in each cylinder may not be calculated.

Therefore, in this embodiment, the injection amount variation correction control is executed on condition that the injection amount of the fuel injection valve 31 is within a predetermined range.
Here, the lower limit value of the predetermined range is, for example, not less than the minimum injection amount of the fuel injection valve 31 (minimum value of the injection amount that can be normally injected) and the calculation error included in the calculation value of the fuel pressure drop amount, The minimum value of the injection amount that can correctly determine the variation in the injection amount of each cylinder based on the amount of fuel pressure drop due to the fuel injection of each cylinder without the variation due to the injection amount variation being too small relative to the variation caused by the resolution or the like Set it to a slightly larger value.

  On the other hand, the upper limit value of the predetermined range is, for example, the required number of fuel injections until the fuel pressure decreases to the normal target fuel pressure (the fuel pressure before the pressure increase) during the pump discharge stop period after increasing the fuel pressure. Is set to a maximum value of the injection amount that can be executed or a value slightly smaller than that.

  In this way, it is possible to reliably calculate the amount of fuel pressure drop due to fuel injection in each cylinder during the pump discharge stop period after increasing the fuel pressure, and to calculate each fuel pressure drop amount based on the fuel pressure drop due to fuel injection in each cylinder. It is possible to correctly determine the cylinder injection amount variation.

  In this embodiment, the injection amount variation correction control is executed on condition that the fuel pressure is within a predetermined range. Here, the predetermined range is set, for example, to a range of fuel pressure that is not more than the upper limit value of the system fuel pressure and does not adversely affect drivability and fuel consumption. In this way, injection amount variation correction control can be executed without adversely affecting drivability and fuel consumption.

  Further, in this embodiment, the injection amount variation correction control is executed on the condition that the injection pattern of the fuel injection valve 31 is a predetermined injection pattern. Here, the predetermined injection pattern is, for example, an injection pattern (for example, an intake stroke of each cylinder) in which fuel injection of the fuel injection valve 31 is performed with only one cylinder during a fuel pressure detection timing when calculating a fuel pressure drop amount due to fuel injection. The intake stroke is a one-time injection pattern in which fuel is injected once at a time.

  In this way, the amount of fuel pressure drop due to fuel injection in the corresponding cylinder can be accurately calculated without being affected by the fuel pressure drop due to fuel injection in other cylinders, and the amount of fuel pressure drop due to fuel injection in each cylinder. Can be calculated with high accuracy.

  In this embodiment, during the injection amount variation correction control, the fuel pressure drop amount due to the fuel injection of each cylinder is calculated during the pump discharge stop period after increasing the fuel pressure, but the high pressure pump 14 supplies the fuel at the maximum discharge amount. In the case of the full discharge state in which discharge is performed, the fuel pressure cannot be increased any further, so that the injection amount variation correction control cannot be executed.

  Therefore, in this embodiment, the injection amount variation correction control is executed on the condition that the high pressure pump 14 is not in the full discharge state in which the fuel is discharged at the maximum discharge amount (is in the non-full discharge state). In this way, the injection amount variation correction control can be executed when the high-pressure pump 14 is not in the full discharge state, and the injection amount variation correction control can be reliably executed.

Further, during the fuel cut in which the fuel injection of the fuel injection valve 31 is stopped, the fuel pressure drop amount due to the fuel injection cannot be calculated, so the injection amount variation correction control cannot be executed.
Therefore, in this embodiment, the injection amount variation correction control is executed on the condition that the fuel cut for stopping the fuel injection of the fuel injection valve 31 is not being performed (the fuel is not being cut). In this way, the injection amount variation correction control can be executed when the fuel cut is not being performed, and the injection amount variation correction control can be reliably executed.

  In addition, when normal fuel injection is not possible due to a lack of gas (insufficient fuel), the amount of fuel pressure drop due to fuel injection changes due to the influence, so the amount of fuel pressure drop due to fuel injection in each cylinder is The information does not accurately reflect the variation in the injection amount of each cylinder. For this reason, when the injection amount variation correction control is executed, the injection amount variation of each cylinder cannot be corrected correctly, and the injection amount of each cylinder may be erroneously corrected.

  Therefore, in this embodiment, the injection amount variation correction control is executed on condition that the main F / B correction amount is not more than a predetermined value. Here, the predetermined value is set to, for example, the upper limit value of the normal range of the main F / B correction amount.

  That is, when the main F / B correction amount is larger than the predetermined value, it is determined that the fuel cannot be normally injected due to lack of gas or the like, and the injection amount variation correction control is prohibited. On the other hand, when the main F / B correction amount is equal to or less than the predetermined value, it is determined that fuel injection is normally performed, and the injection amount variation correction control is permitted. In this way, it is possible to prevent the injection amount variation correction control from being executed when the fuel cannot be normally injected due to lack of gas or the like, and to prevent erroneous correction of the injection amount of each cylinder. .

  Further, when the injection amount variation correction control is executed during the normal control of the high-pressure pump 14, the injection period of the fuel injection valve 31 and the discharge period of the high-pressure pump 14 may overlap depending on the engine operating region. In 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 amount of fuel pressure drop due to fuel injection of the fuel injection valve 31 is accurately affected by the influence of the fuel pressure increase due to fuel discharge of the high-pressure pump 14. It becomes difficult to calculate well.

Therefore, in this embodiment, the injection amount variation correction control is executed on the condition that the injection period of the fuel injection valve 31 and the discharge period of the high-pressure pump 14 are non-overlapping operation regions (non-overlapping operation regions). Yes. In this way, even when the injection amount variation correction control is executed during the normal control of the high-pressure pump 14, the fuel pressure by the fuel injection of the fuel injection valve 31 is not affected by the increase in the fuel pressure due to the fuel discharge of the high-pressure pump 14. The amount of drop can be calculated with high accuracy, and the amount of fuel pressure drop due to fuel injection in each cylinder can be calculated with high accuracy.
Hereinafter, the processing contents of each routine for correcting the injection amount variation in FIGS. 3 and 4 executed by the ECU 38 in the present embodiment will be described.

[Injection amount variation correction main routine]
The injection amount variation correction main routine shown in FIG. 3 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 steps 101 to 108, it is determined whether or not an execution condition for injection amount variation correction control is satisfied. Here, as the execution conditions of the injection amount variation correction control, for example, the following conditions (1) to (8) are determined.

(1) The engine is in steady operation (step 101)
(2) The injection amount of the fuel injection valve 31 is within a predetermined range (step 102).
(3) The fuel pressure is within the predetermined range (step 103)
(4) The injection pattern of the fuel injection valve 31 is a predetermined injection pattern (step 104).
(5) The high-pressure pump 14 is in a non-full discharge state (not a full discharge state) (step 105)
(6) Non-fuel cut in progress (not in fuel cut) (step 106)
(7) The main F / B correction amount is not more than a predetermined value (step 107).
(8) Non-overlapping operation region (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) (step 108).

If all of the above conditions (1) to (8) are satisfied, the execution condition of the injection amount variation correction control is established, but there is a condition that does not satisfy any one of the above conditions (1) to (8). In this case, the execution condition of the injection amount variation correction control is not satisfied.
If it is determined in steps 101 to 108 that the execution condition of the injection amount variation correction control is not satisfied, the injection amount variation correction control is prohibited and this routine is terminated.

  On the other hand, if it is determined in steps 101 to 108 that the execution condition of the injection amount variation correction control is satisfied, the injection amount variation correction control is permitted, and the process proceeds to step 109, where the injection amount shown in FIG. A variation correction routine is executed.

[Injection amount variation correction routine]
The injection amount variation correction routine shown in FIG. 4 is a subroutine executed in step 109 of the injection amount variation correction main routine of FIG. When this routine is started, first, in step 201, the high pressure pump 14 increases the fuel pressure from the normal target fuel pressure (target fuel pressure corresponding to the engine operating state) to the target fuel pressure for boosting, and then proceeds to step 202. Discharge of the high-pressure pump 14 is stopped.

  Thereafter, the routine proceeds to step 203, 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 embodiment, the fuel pressure detection timing is set to the pump cam top (the timing at which the piston 19 of the high-pressure pump 14 becomes top dead center), and the fuel pressure is detected before the start of fuel injection and after the end of fuel injection in each cylinder. For each cylinder, the difference between the fuel pressure before the start of fuel injection and the fuel pressure after the end of fuel injection is calculated as the amount of fuel pressure drop due to fuel injection.

  Thereafter, the process proceeds to step 204, and, for example, when the fuel pressure is reduced to the normal target fuel pressure, the discharge of the high-pressure pump 14 is resumed. Thereafter, the routine proceeds to step 205, where the average value of the fuel pressure drop due to fuel injection in all cylinders is calculated, and the deviation between the fuel pressure drop due to 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 process proceeds to step 206, 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 injection pulse width (injection time) of the fuel injection valve 31 of each cylinder for each cylinder by correcting the required injection amount using the injection amount variation correction amount for each cylinder. The variation in the injection amount of the fuel injection valve 31 of the cylinder is reduced (the variation in the injection amount between the cylinders is reduced).

  In the present embodiment described above, whether or not the execution condition of the injection amount variation correction control is satisfied is that the engine is in steady operation, the injection amount of the fuel injection valve 31 is within a predetermined range, the fuel pressure Is determined based on whether or not all the various conditions such as is within a predetermined range are satisfied. When it is determined that the execution condition of the injection amount variation correction control is satisfied, the fuel pressure drop amount 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, and Injection amount variation correction control for correcting variation in the injection amount of the fuel injection valve 31 of each cylinder based on the amount of fuel pressure drop due to fuel injection of the cylinder is executed. As a result, the amount of fuel pressure drop due to fuel injection in each cylinder can be accurately calculated, and variations in the injection amount of each cylinder can be corrected correctly, and erroneous correction of the injection amount of each cylinder can be prevented.

  Note that the method of correcting the variation in the injection amount of the fuel injection valve 31 of each cylinder based on the amount of fuel pressure drop due to the fuel injection of each cylinder is not limited to the method described in the above embodiment, and may be changed as appropriate.

  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 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)

Claims (7)

The present invention is applied to a system for supplying fuel discharged from a high-pressure pump (14) to a fuel injection valve (31) of each cylinder of an internal combustion engine through a high-pressure fuel passage (29, 30), and in the high-pressure fuel passage (29, 30). A fuel pressure sensor (32) for detecting the fuel pressure (hereinafter referred to as "fuel pressure"), and a fuel pressure drop amount due to fuel injection of the fuel injection valve (31) for each cylinder based on the output of the fuel pressure sensor (32) And injection amount variation correction means (38) for performing injection amount variation correction control for correcting the variation in the injection amount of the fuel injection valve (31) of each cylinder based on the amount of fuel pressure drop due to the fuel injection. In a control device for an internal combustion engine,
The injection amount variation correction means (38) executes the injection amount variation correction control when the operating state of the internal combustion engine is in a steady state.
The injection amount variation correction means (38) executes the injection amount variation correction control on condition that the injection period of the fuel injection valve (31) and the discharge period of the high-pressure pump (14) do not overlap. A control device for an internal combustion engine characterized by the above.   The injection amount variation correction means (38) executes the injection amount variation correction control on condition that the injection amount of the fuel injection valve (31) is within a predetermined range. Control device for internal combustion engine.   The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the injection amount variation correcting means (38) executes the injection amount variation correction control on condition that the fuel pressure is within a predetermined range. .   The injection amount variation correction means (38) executes the injection amount variation correction control on condition that the injection pattern of the fuel injection valve (31) is a predetermined injection pattern. The control apparatus for an internal combustion engine according to any one of the above.   The injection amount variation correction means (38) executes the injection amount variation correction control on condition that the high pressure pump (14) is not in a full discharge state in which fuel is discharged at a maximum discharge amount. Item 5. The control device for an internal combustion engine according to any one of Items 1 to 4.   The injection quantity variation correction means (38) executes the injection quantity variation correction control on the condition that the fuel injection of the fuel injection valve (31) is not under fuel cut. The control apparatus for an internal combustion engine according to any one of claims 1 to 5.   The injection amount variation correction means (38) has a correction amount of air-fuel ratio feedback control for correcting the injection amount of the fuel injection valve (31) so that the air-fuel ratio of the exhaust gas of the internal combustion engine matches the target air-fuel ratio. The control apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the injection amount variation correction control is executed on condition that the value is equal to or less than a predetermined value.

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