JP2008128034A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an error in a fuel injection amount caused by a delay in movement of fuel in a common rail and prevent deterioration of exhaust gas. <P>SOLUTION: A movement index indicating the delay of fuel movement in the common rail 126 is calculated by a movement index calculation means 707 based on the fuel injection amount of an injector 112, and the fuel injection amount by the injector 112 is corrected by a pulse width correction means 709 based on the movement index calculated by the movement index calculation means 707. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for a fuel system of a direct injection internal combustion engine in which fuel is injected into a combustion chamber by an injector installed on a common rail.

  In a cylinder injection internal combustion engine, in order to inject a target amount of fuel from an injector (fuel injection valve), the fuel pressure (fuel pressure) of the common rail where the injector is installed is measured by a fuel pressure sensor, and the fuel pressure is The fuel injection pulse width is calculated by correcting the valve opening time of the injector.

  One of the problems of the cylinder injection internal combustion engine is the fuel pressure pulsation in the common rail. Since the fuel boosted by the reciprocating high-pressure pump is intermittently supplied to the common rail, intermittent fuel movement occurs in the common rail due to fuel discharge from the high-pressure pump and fuel injection from the injector. Due to this intermittent fuel movement, fuel pressure pulsation is generated in the common rail, and proper fuel pressure correction is not performed by the fuel pressure pulsation, and the fuel injection amount of the injector may deviate from the target value, which may cause exhaust deterioration.

  As a conventional technique for solving this problem, from the time when fuel pressure is detected by the fuel pressure sensor based on fuel variable elements such as the fuel injection amount of the injector, the fuel discharge amount of the high pressure pump, and the fuel leak amount from the common rail, the fuel injection is started There is known a fuel injection control device that corrects a fuel injection amount by estimating a change in fuel pressure up to (for example, Patent Document 1).

  In addition, a fuel injection control device that corrects the fuel injection amount using a fuel pressure measurement value immediately before fuel injection at the time when the fuel pressure boosted by the high pressure pump is not stable is known (for example, Patent Document 2).

JP 2000-257478 A JP 2003-41980 A

  However, in order to estimate the change in fuel pressure from the fuel variable element, it is necessary to grasp the discharge characteristics of the high-pressure pump, the injection characteristics of the injector, and the characteristics of the fuel. For example, since it is affected by temperature), complicated calculation and adaptation are required.

  In order to correct the fuel injection amount using the fuel pressure measurement value immediately before fuel injection, a highly responsive and accurate fuel pressure sensor for measuring the change in fuel pressure immediately before injection is required.

  In addition, in the above-described conventional technology, the fuel injection amount correction corresponding to the fuel pressure does not consider the pressure distribution due to the delay of fuel movement in the common rail, so an error occurs between the measured or estimated fuel pressure and the fuel injection pressure of the injector. There is a possibility that correct fuel injection amount correction is not performed.

  In particular, in recent direct injection internal combustion engines, the range of injectors and high-pressure pumps for the purpose of reducing exhaust emissions and improving fuel efficiency is increasing, and the size of common rails is becoming smaller. An error in the fuel injection amount due to the delay is likely to occur, and the risk of exhaust deterioration due to this is increasing.

  The present invention has been made in view of the problems to be solved, and the object of the present invention is to produce a fuel injection amount caused by a fuel movement delay in a common rail by a conventional fuel pressure sensor and simple arithmetic processing. An object of the present invention is to provide a fuel system control device that reduces errors and prevents exhaust deterioration.

  In order to achieve the above object, a control device for an internal combustion engine according to the present invention includes a high-pressure pump that boosts fuel and discharges fuel to a common rail, an injector that injects fuel stored in the common rail, and a fuel that is stored in the common rail. A control device for an internal combustion engine, which controls the high-pressure pump and the injector based on a fuel pressure measurement value by the fuel pressure sensor. A movement index calculating means for calculating a movement index representing a delay in fuel movement in the common rail based on the amount; and a fuel injection for correcting a fuel injection amount by the injector based on the movement index calculated by the movement index calculating means A quantity correction means.

  In the control apparatus for an internal combustion engine according to the present invention, preferably, the movement index calculating means increases the movement index in response to an increase in the fuel injection amount of the injector, and further the temperature of the fuel in the common rail is normally When the fuel pressure of the common rail is lower than normal or lower than normal, the movement index is made larger than normal.

  The control apparatus for an internal combustion engine according to the present invention further preferably includes pulsation detecting means for determining the presence or absence of fuel pressure pulsation in the common rail based on a fuel pressure measurement value by the fuel pressure sensor, and correcting the fuel injection amount The means corrects the fuel injection amount by the injector based on the presence or absence of the fuel pressure pulsation determined by the pulsation detecting means in addition to the movement index calculated by the movement index calculating means.

  In the control apparatus for an internal combustion engine according to the present invention, preferably, the pulsation detecting means determines that there is a fuel pressure pulsation when a change in fuel pressure measured by the fuel pressure sensor is greater than a predetermined threshold value, Otherwise, it is determined that there is no fuel pressure pulsation. This threshold value is preferably increased when the fuel pressure of the common rail is small.

  In the control device for an internal combustion engine according to the present invention, preferably, the fuel injection amount correction means calculates a fuel injection correction amount based on the movement index calculated by the movement index calculation means, and the pulsation detection means The method for calculating the fuel injection correction amount is changed according to the determined presence or absence of fuel pressure pulsation. Preferably, the fuel injection correction amount with pulsation is calculated larger than that without pulsation.

  The control apparatus for an internal combustion engine according to the present invention preferably further includes comparing the predetermined value predetermined based on the engine speed and the load with the fuel injection correction amount by the fuel injection amount correction means. Fuel system abnormality determining means for diagnosing an abnormality in a fuel system including the injector, the high-pressure pump, the fuel pressure sensor, and the common rail, and outputting a warning when the abnormality is diagnosed.

  In the control apparatus for an internal combustion engine according to the present invention, preferably, the predetermined value of the fuel system abnormality determination means is the engine speed at which fuel pressure pulsation occurs, a load region (pulsation region), and an engine in which fuel pressure pulsation does not occur. The rotational speed and the load region (non-pulsation region) are individually determined, and the predetermined value of the pulsation region is larger than the predetermined value of the non-pulsation region.

  According to the control apparatus for an internal combustion engine of the present invention, the movement index representing the fuel movement delay in the common rail is calculated by the movement index calculating means based on the fuel injection amount of the injector, and the fuel by the injector is calculated based on the calculated movement index. Since the injection amount is corrected by the fuel injection amount correction means, the fuel injection amount error due to the fuel movement delay in the common rail is reduced and the exhaust deterioration is prevented by simple arithmetic processing without requiring a highly responsive fuel pressure sensor. be able to.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the overall configuration of a direct injection internal combustion engine to which an engine control apparatus according to the present invention is applied.

  The cylinder injection internal combustion engine 107 (hereinafter referred to as the engine 107) defines a plurality of combustion chambers 107c by a cylinder block 107b and a piston 107a.

  The intake air introduced into the combustion chamber 107 c of the engine 107 is taken in from the inlet portion 102 a of the air cleaner 102, passes through an air flow meter (air flow sensor) 103 which is one of the operating state measuring means of the engine 107, and the intake air flow is reduced. The collector 106 is entered through the throttle body 105 in which the electric throttle valve 105a to be controlled is accommodated. The electric throttle valve 105a is driven by the electric motor 124 and the opening degree is set.

  The airflow sensor 103 outputs a signal representing the intake air flow rate to the control unit 115 which is an engine control device. The throttle body 105 is provided with a throttle sensor 104 that detects the opening degree of the electric throttle valve 105a as one of the operating state measuring means of the engine 107. The throttle sensor 104 outputs a signal indicating the opening degree of the electric throttle valve 105a to the control unit 115.

  The air sucked into the collector 106 is distributed and supplied to each combustion chamber 107c by the intake pipe 101 connected to the cylinder block 107b.

  Fuel such as gasoline is primarily pressurized from the fuel tank 108 by the fuel pump 109, regulated to a constant pressure by the fuel pressure regulator 110, and secondarily pressurized to a high pressure by the high-pressure fuel pump 111, and then supplied to the common rail 126. Pumped. The high pressure fuel is directly injected into the combustion chamber 107c by the injector 112 installed on the common rail 126 for each combustion chamber 107c.

  A fuel pressure sensor 121 is attached to the common rail 126. The fuel pressure sensor 121 detects (measures) the fuel pressure of the common rail 126 and outputs a signal indicating the fuel pressure (fuel pressure) to the control unit 115.

  A fuel temperature sensor 125 is attached to the common rail 126. The fuel temperature sensor 125 detects (measures) the fuel temperature of the common rail 126 and outputs a signal representing the fuel temperature to the control unit 115.

  A spark plug 114 is attached to the cylinder block 107b for each combustion chamber 107c. The fuel injected into the combustion chamber 107 c is ignited by the spark plug 114 by the ignition signal that has been increased in voltage by the ignition coil 113.

  A cam angle sensor 116 is attached to the camshaft 100 of the exhaust valve 107d. The cam angle sensor 116 outputs a signal for detecting the phase of the camshaft 100 to the control unit 115. The cam angle sensor 116 may be attached to the cam shaft 122 on the intake valve 107e side.

  A water temperature sensor 123 for detecting the cooling water temperature of the engine 107 is attached to the cylinder block 107b. The water temperature sensor 123 outputs a signal indicating the coolant temperature of the engine 107 to the control unit 115.

  In order to detect the rotation and phase of the crankshaft 107f of the engine 107, a crank angle sensor 117 is provided on the crankshaft 107f. The crank angle sensor 117 outputs a signal representing the rotation and phase of the crankshaft 107 f to the control unit 115.

  A three-way catalyst 120 is provided in the exhaust pipe 119. An air-fuel ratio sensor 118 is provided on the upstream side of the three-way catalyst 120. The air-fuel ratio sensor 118 detects oxygen in the exhaust gas and outputs a detection signal to the control unit 115.

  The control unit 115 is of an electronic control type by a microcomputer, and performs air-fuel ratio control, ignition control, fuel pressure control, and fuel system abnormality diagnosis.

  FIG. 2 shows an outline of a fuel system of a direct injection internal combustion engine to which a control device (engine control device) according to the present invention is applied. The control unit 115 includes injector control means 202 and high-pressure pump control means 203.

  The injector control means 202 basically includes an injector based on the amount of air detected by the air flow meter 103, the air-fuel ratio detected by the air-fuel ratio sensor 118, and the engine speed detected by the crank angle sensor 117. The valve opening time of 112 is controlled. As a result, a target amount of fuel is injected from the injector 112 into the combustion chamber 107c, and air-fuel ratio control is performed.

  The high pressure pump control means 203 includes a fuel pressure measurement value obtained by the fuel pressure sensor 121 installed on the common rail 126, a fuel temperature measurement value obtained by the fuel temperature sensor 125 installed on the common rail 126, and a cam 211 that drives the high pressure fuel pump 111. The opening and closing of the solenoid valve 212 of the high-pressure fuel pump 111 is controlled based on the output of the cam angle sensor 116 that detects the phase of the camshaft 100 that includes Thus, fuel pressure control is performed to increase the fuel pressure in the common rail 126 to the target pressure.

  The fuel movement in the common rail 126 is caused by fuel discharge by the high-pressure fuel pump 111 and fuel injection into the cylinder by the injector 112. That is, fuel movement occurs in the common rail 126 due to fuel discharge from the high-pressure fuel pump 111 and fuel injection from the injector 112, and the fuel movement delay increases as the fuel injection amount increases. Further, if the amount of fuel in the common rail 126 changes greatly due to a delay in fuel movement in the common rail 126, this is detected as an output fluctuation (fuel pressure pulsation) of the fuel pressure sensor 121.

  The high-pressure fuel pump 111 is a plunger reciprocating type, and in this embodiment, as shown in FIGS. 2 and 3, the fuel tank 108 side is moved by the vertical movement of the plunger 213 driven by the cam 211. The fuel supplied from the fuel pipe is sucked into the pump chamber 214 via the suction check valve 215, and the fuel sucked into the pump chamber 214 is discharged to the fuel pipe on the common rail 126 side via the discharge check valve 216.

  The discharge amount of the high-pressure fuel pump 111 is adjusted by forcibly opening the suction check valve 215 by the electromagnetic valve 212 while the plunger is raised, and causing the fuel in the pump chamber 214 to flow backward to the fuel tank 108 side. Since the high-pressure fuel pump 111 intermittently discharges fuel in synchronization with the cam angle of the engine 107, fuel movement to the common rail 126 occurs.

  FIG. 4 shows the drive signal of the high-pressure fuel pump 111 with respect to the lift amount of the plunger 213 (electromagnetic valve 212 opening / closing signal), the drive signal of the injector 112 (injection pulse signal), and the common rail 126 measured by the fuel pressure sensor 121. It is an example of the time chart which showed the relationship of these fuel pressures typically.

  The high pressure fuel pump 111 sucks fuel into the pump chamber 214 while the plunger 213 moves from the top dead center to the bottom dead center, and from the pump chamber 214 while the plunger 213 moves from the bottom dead center to the top dead center. Discharge the fuel. The fuel discharge amount is determined mainly by the closing timing a of the electromagnetic valve 212 (the forced valve opening release timing of the suction check valve 215), and the discharge amount is increased as the closing timing a of the electromagnetic valve 212 is delayed from the bottom dead center of the plunger 213. Decrease. On the other hand, the injector 112 opens in response to the injection pulse signal, and if the fuel pressure is the same, the injection amount increases as the open time of the injection pulse signal is longer.

  At this time, the fuel pressure in the common rail 126 rises due to fuel discharge from the high-pressure fuel pump 111, and repeatedly fluctuates such that it falls due to fuel injection from the injector 112. That is, fuel pressure pulsation is generated.

  In practice, a pressure distribution due to fuel movement is generated in the common rail 126, and there is a pressure difference (fuel pressure difference) between the installation position of the fuel pressure sensor 121 and the installation position of the injector 112. Since the fuel pressure sensor 121 is normally attached to a place where it is not affected by the pressure fluctuation, it is difficult to measure the delay of the fuel movement in the common rail 126 from the fuel pressure measurement value of the fuel pressure sensor 121.

  Here, a fuel movement delay factor in the common rail 126 and a fuel injection amount error due to the fuel movement delay will be described.

  FIG. 5 shows the relationship between the pulse width necessary for injecting the target fuel amount and the fuel pressure. In general, it is known that a pulse width T1 that is equal fuel with respect to a predetermined injection pulse width T0 at a predetermined fuel pressure P0 is T1 = T0 * sqrt (P0 / P1) with respect to the fuel pressure P1.

  Normally, the fuel pulse width is corrected according to the fuel pressure of the common rail 126 measured by the fuel pressure sensor 121 using this relationship, and the robustness of the fuel injection amount with respect to the fuel pressure is ensured.

  However, as described above, when there is a fuel pressure difference between the installation position of the fuel pressure sensor 121 and the installation position of the injector 112, or as shown in FIG. 6, the fuel pressure sampling time (time) Tp by the fuel pressure sensor 121 and the fuel If there is a fuel pressure difference between the fuel pressure A at the time of fuel pressure sampling and the fuel pressure B at the time of fuel injection due to the time lag of the injection time Ti for actually injecting the fuel from the injector 112, the fuel injection is performed according to the fuel pressure difference. There is an error in the quantity.

  FIG. 7 shows details of one embodiment of the engine control apparatus according to the present invention. The engine control apparatus of this embodiment is embodied by software processing executed by an electronic control type control unit 115 by a microcomputer, and includes an injection amount calculation means 701, a pulse width calculation means 702, and an injector drive. The controller 703 includes a discharge amount calculator 704, a suction valve angle calculator 705, a high-pressure pump drive controller 706, a movement index calculator 707, a pulsation detector 708, and a pulse width corrector 709.

  The injection amount calculation means 701 calculates a fuel injection amount (basic fuel injection amount) based on the intake air amount, engine speed, target air-fuel ratio, and the like.

  The pulse width calculation means 702 calculates the drive pulse width of the injector 112 based on the fuel injection amount calculated by the injection amount calculation means 701 and the fuel pressure of the common rail 126 detected by the fuel pressure sensor 121.

  The injector drive control means 703 outputs an injector drive signal corresponding to the drive pulse width (injection pulse signal) of the injector 112 calculated by the pulse width calculation means 702 to the injector 112. The injector 112 is driven by an injector drive signal output from the injector drive control means 703.

  In order to control the fuel pressure of the common rail 126 to the target fuel pressure, the discharge amount control calculating means 704 is a high pressure from the fuel pressure of the common rail 126 detected by the fuel pressure sensor 121 and the fuel injection amount calculated by the injection amount calculating means 701. The discharge amount of the fuel pump 111 is calculated.

  The intake valve angle calculation means 705 uses the cam angle sensor 116 to determine the intake valve angle that determines the forced valve opening release timing of the intake check valve 215 of the high-pressure fuel pump 111 based on the discharge amount calculated by the discharge amount control calculation means 704. It is calculated as an angle corresponding to the detected phase (cam angle) of the camshaft 100.

  The high pressure pump drive control means 706 receives a signal indicating the cam angle detected by the cam angle sensor 116, and the electromagnetic pressure of the high pressure fuel pump 111 according to the cam angle and the intake valve angle calculated by the intake valve angle calculation means 705. An electromagnetic drive signal for driving the valve 212 is output to the electromagnetic valve 212. Thereby, the closing timing of the electromagnetic valve 212 is set to the feedback compensation type according to the intake valve angle calculated by the intake valve angle calculating means 705.

  Based on the fuel injection amount calculated by the injection amount calculation unit 701, the movement index calculation unit 707 calculates a movement index as a parameter for estimating the fuel movement delay in the common rail 126. The movement index calculation means 707 basically increases the movement index as the fuel injection amount of the injector 112 increases, and then, when the fuel temperature of the common rail 126 detected by the fuel temperature sensor 125 is lower than normal. Alternatively, when the fuel pressure of the common rail 126 detected by the fuel pressure sensor 121 is lower than normal, the movement index is made larger than normal.

  The pulsation detecting means 708 determines and detects the presence or absence of fuel pressure pulsation in the common rail 126 based on the fuel pressure of the common rail 126 detected by the fuel pressure sensor 121 (output signal of the fuel pressure sensor 121 = fuel pressure measurement value). In this embodiment, the pulsation detecting means 708 determines that there is a fuel pressure pulsation when the change in the fuel pressure measured by the fuel pressure sensor 121 is greater than a predetermined threshold value, and determines that there is no fuel pressure pulsation otherwise. . The threshold value for this determination is set according to the fuel pressure of the common rail 126 detected by the fuel pressure sensor 121, and is set to a larger value as the fuel pressure is lower.

  The pulsation detecting means 708 sets the pulsation flag to “1” when there is a fuel pressure pulsation, and sets the pulsation flag to “0” when there is no fuel pressure pulsation.

  The pulse width correction unit 709 is a fuel injection amount correction unit, and calculates a pulse width correction amount according to the movement index calculated by the movement index calculation unit 707 and the presence or absence of fuel pressure pulsation determined by the pulsation detection unit 708. . In this embodiment, the pulse width correction unit 709 calculates the pulse width correction amount based on the movement index, changes the calculation method of the pulse width correction amount according to the value of the pulsation flag, and has no pulsation (pulsation flag = Compared with 0), the pulse width correction amount with pulsation (pulsation flag = 1) is calculated larger (see FIG. 11).

  The pulse width correction amount calculated by the pulse width correction unit 709 is input to the pulse width calculation unit 702. As a result, the pulse width calculation means 702 uses the fuel injection amount calculated by the injection amount calculation means 701 and the drive pulse width of the injector 112 calculated based on the fuel pressure of the common rail 126 detected by the fuel pressure sensor 121 as a pulse. Correction is performed by the pulse width correction amount calculated by the width correction unit 709, and the injection pulse signal having the corrected drive pulse width is passed to the injector drive control unit 703.

  Thereby, in this embodiment, the delay of fuel movement in the common rail 126 is estimated by the fuel injection amount (basic fuel injection amount), and the presence or absence of fuel pressure pulsation in the common rail 126 is detected by the output signal of the fuel pressure sensor 121, Based on these two pieces of information, the fuel injection pulse width is corrected. This correction reduces or eliminates the fuel injection amount error caused by the fuel movement delay in the common rail 126, and prevents the exhaust performance from being deteriorated due to the fuel movement delay in the common rail 126.

  Next, a specific operation of the engine control apparatus according to the present embodiment will be described in detail with reference to the flowchart of FIG.

  First, in step S801, the injection amount calculation unit 701 performs an injection amount calculation process for calculating a basic injection amount based on the intake air amount, the engine speed, the target air-fuel ratio, and the like.

  Next, in step S802, the movement index calculation means 707 calculates the movement index from the fuel injection amount calculated by the injection amount calculation means 701.

  The movement index is a movement delay of fuel from the fuel discharge of the high-pressure fuel pump 111 to the fuel injection of the injector 112, and increases as the fuel injection amount by the injector 112 increases as shown in FIG. This is because the larger the fuel injection amount, the larger the fuel movement amount and the longer it takes to move.

  Further, the smaller the capacity of the common rail 126, the narrower the moving space and the longer it takes to move, so the moving index is reduced. Also, the greater the overlap between the discharge and injection timings, the smaller the resistance of fuel movement and the longer it takes to move, so the movement index is made smaller. These can be set to appropriate values by adaptation.

  Further, as shown in FIG. 9B, when the fuel pressure of the common rail 126 measured by the fuel pressure sensor 121 is lower than normal, or the fuel temperature of the common rail 126 measured by the fuel temperature sensor 125 is higher than normal. When the temperature is low, the fuel movement is slower than normal due to the influence of the viscosity of the fuel. For example, when the fuel temperature is low at the start (cold start) or when the fuel pressure is low, Make it larger than during normal operation later.

  Next, in step S803, the pulsation detecting means 708 detects the presence or absence of fuel pressure pulsation in the common rail 126 from the output of the fuel pressure sensor 121.

  Here, as a pulsation detection method, as shown in FIG. 10, the presence or absence of fuel pressure pulsation is determined by a fuel pressure change value (for example, the difference between the maximum fuel pressure and the minimum fuel pressure measured in one cycle of the plunger 213 of the high-pressure fuel pump 111). Determine and set the threshold according to the fuel pressure.

  In general, the fuel pressure sensor 121 has a lower measurement accuracy as the pressure becomes lower. Therefore, as shown in FIG. 10, by setting the threshold value higher as the fuel pressure becomes lower, erroneous detection of pulsation can be prevented.

  Next, in step S804, the presence / absence of pulsation is determined. If there is pulsation, the pulsation flag = 1, the process proceeds to step S805, and the pulse width correction unit 709 performs pulse width correction suitable for the presence of pulsation. On the other hand, if there is no pulsation, the pulsation flag = 0, the process proceeds to step S806, and the pulse width correction unit 709 performs pulse width correction suitable for no pulsation.

  Here, an example of pulse width correction performed in step S805 and step S806 will be described with reference to FIG. The pulse width correction characteristics shown in FIG. 11 can be set in conformity, and the pulse width correction amount when the pulsation flag = 0 when the movement index is small, and the pulse width when the pulsation flag = 1 when the movement index is large. The correction amount can be obtained by adaptation. For a region that cannot be obtained by matching, the minimum value is substituted when the pulsation flag = 1, and the maximum value is substituted when the pulsation flag = 0.

  Thereby, even if the fuel movement delay varies somewhat due to variations in the characteristics of the injector 112 and the high-pressure fuel pump 111, pulse width correction correction based on the injection amount can be performed. Moreover, since the method demonstrated above can be implement | achieved by the map calculation based on a fitting result, the delay of fuel movement can be correct | amended easily.

  Further, only the presence or absence of fuel pressure pulsation is detected from the output signal of the fuel pressure sensor 121, and the magnitude of the pulsation is estimated from the fuel injection amount calculated by the injection amount calculating means 701. Pulse width correction can be performed without using the high-precision fuel pressure sensor 121.

  FIG. 12 shows details of another embodiment of the engine control apparatus according to the present invention. 12, parts corresponding to those in FIG. 7 are denoted by the same reference numerals as those in FIG. 7, and description thereof is omitted.

  The engine control apparatus of the present embodiment is also embodied by software processing executed by the electronic control type control unit 115 by a microcomputer, and includes an injection amount calculation means 701, a pulse width calculation means 702, and an injector drive control means. 703, discharge amount calculation means 704, intake valve angle calculation means 705, high pressure pump drive control means 706, movement index calculation means 707, pulsation detection means 708, pulse width correction means 709, and fuel system abnormality determination means 710 .

  The fuel system abnormality determination means 710 detects an abnormality in the fuel system by comparing the pulse width correction amount by the pulse width calculation means 702 with a predetermined value that is predetermined according to the engine speed and engine load. Output a warning.

  Next, a specific operation of the engine control apparatus according to the present embodiment will be described in detail with reference to the flowchart of FIG.

  From step S1301 to step S1306, the same processing as step S801 to step S806 in FIG. 8 is performed. That is, in step S1301, an injection amount calculation process for calculating a basic injection amount based on the intake air amount, the engine speed, the target air-fuel ratio, and the like is performed. Next, in step S1302, a movement index is calculated from the injection amount, and in step S1303, pulsation is detected from the value of the fuel pressure sensor 121. In step S1304, the presence / absence of pulsation is determined. If there is pulsation, the process proceeds to step S1305, and pulse width correction with pulsation is performed. If there is no pulsation, the process proceeds to step S1306, and pulse width correction without pulsation is performed. I do.

  In the present embodiment, the processing after step S1307 is further performed to diagnose an abnormality in the fuel system and prevent exhaust deterioration. For this reason, in step S1307, as shown in FIG. 14, the region where the fuel pressure pulsation occurs (pulsation region) and the region where the fuel pressure pulsation does not occur (non-pulsation region) are determined by a bench test or the like. When the pulse width correction amount by the pulse width calculation means 702 is smaller than the first predetermined value in the pulsation region, and when the pulse width correction amount is larger than the second predetermined value in the non-pulsation region Therefore, it is determined that there is an abnormality in the fuel system, and the process proceeds to step S1308. Otherwise, it is determined as normal and the process proceeds to step S1309.

  Here, the first predetermined value is the minimum value of the pulse width correction amount when the fuel pressure pulsation is detected by the fuel pressure sensor 121, and the second predetermined value is smaller than the first predetermined value. Set.

  As a result, it can be diagnosed that the fuel system is abnormal when the fuel pressure pulsation does not occur in the region where the fuel pressure pulsation occurs or when the fuel pressure pulsation occurs in the region where the fuel pressure pulsation does not occur.

  In the fuel system abnormality determination process in step S1308, when the pulse width correction amount is large in the non-pulsation region, a warning is output that an abnormality has occurred in the injector 112 or the high-pressure fuel pump 111, and the pulse width correction amount is in the pulsation region. When it is small, a warning may be output if an abnormality has occurred in the common rail 126 or the fuel pressure sensor 121.

  Further, when it is determined that the fuel system is abnormal and a warning is output, it is possible to prevent exhaust gas deterioration due to a fuel system abnormality by prohibiting pulse width correction using a movement index or the like.

  On the other hand, in step S1309, if a warning is issued, the warning is canceled and pulse width correction is permitted. As a result, when the fuel system is normal, the pulse width correction can be performed promptly to prevent exhaust deterioration.

  That is, in the present embodiment, a fuel system abnormality is detected by comparing a movement index and a correction amount determined according to the presence or absence of pulsation with a predetermined value, and a warning is issued in the event of an abnormality to prompt repair. At the same time, by prohibiting pulse width correction, exhaust deterioration can be prevented even when the fuel system is abnormal.

  The effects of the above-described embodiment will be summarized below.

(1) The movement index representing the fuel movement delay in the common rail is calculated based on the fuel injection amount of the injector, and the presence or absence of fuel pressure pulsation is detected to correct the fuel injection pulse width according to the fuel movement delay. Exhaust deterioration can be prevented.

(2) When the temperature of fuel in the common rail is lower than normal, or when the fuel pressure of the common rail is lower than normal, the movement index is made larger than normal so that the amount of fuel depending on the fuel injection amount and fuel condition The characteristics of the movement delay can be reflected in the pulse width correction, and the exhaust deterioration particularly at the time of low temperature start can be prevented.

(3) Since the pulsation detecting means has pulsation when the pressure change measured by the fuel pressure sensor is larger than a predetermined threshold and further increases the threshold when the fuel pressure is small, Exhaust deterioration at the time of fuel pressure can be prevented.

(4) The pulse width correction means calculates the pulse width correction amount based on the movement index, and further compares the pulse width correction amount calculation method according to the value of the pulsation flag with a pulse with pulsation compared with no pulsation. By changing so that the width correction amount is calculated to be large, the difference in fuel movement due to the presence or absence of pulsation can be reflected in the pulse width correction, and exhaust deterioration can be prevented in a wide operation region regardless of the presence or absence of pulsation.

(5) The fuel system abnormality determination means is configured by an injector, a high-pressure pump, a fuel pressure sensor, and a common rail by comparing a predetermined value determined in advance based on the engine speed and load with a pulse width correction amount. By diagnosing abnormalities in the fuel system and outputting a warning at the time of abnormality diagnosis, exhaust deterioration when the fuel system is abnormal can be prevented in advance. The fuel system abnormality determination means can diagnose the abnormality of the fuel system by comparing the pulse width correction amount in the operation region assumed in advance with a reference (predetermined value) and the actual pulse width correction amount.

(6) The predetermined value determined in advance by the fuel system abnormality determination means based on the engine speed and the load is the engine speed and load region (pulsation region) where the fuel pressure pulsation occurs, and the engine speed where the fuel pressure pulsation does not occur When the fuel pressure pulsation does not occur in the region where the fuel pressure pulsation occurs, the number and the load region (non-pulsation region) are individually determined, and the predetermined value of the pulsation region is larger than the predetermined value of the non-pulsation region. Alternatively, when the fuel pressure pulsation occurs in a region where the fuel pressure pulsation does not occur, it is diagnosed that the fuel system is abnormal, and exhaust deterioration due to the fuel system abnormality can be prevented.

  In the above-described embodiment, the pulse width correction unit 709 is a fuel injection amount correction unit, and depends on the movement index calculated by the movement index calculation unit 707 and the presence or absence of fuel pressure pulsation detected by the pulsation detection unit 708. The pulse width correction amount may be calculated according to the movement index calculated by the movement index calculation means 707 without determining whether or not there is fuel pressure pulsation according to the required specifications. .

The block diagram which shows the whole structure of the cylinder injection type internal combustion engine (engine) to which the control apparatus (engine control apparatus) by this invention is applied. The figure which shows the outline | summary of the fuel system of the direct injection internal combustion engine to which the control apparatus (engine control apparatus) by invention is applied. The schematic block diagram which shows an example of the high pressure pump used for a direct injection internal combustion engine. The time chart which shows an example of operation | movement of the fuel control system of a cylinder injection type internal combustion engine. The graph which shows the relationship between the fuel pressure at the time of injecting equal fuel, and an injection pulse width. Time chart showing an example of fuel pressure and injection pulse width when pulsation occurs The block diagram which shows the detail of one Embodiment of the engine control apparatus by this invention. The flowchart showing the specific operation | movement of one Embodiment of the engine control apparatus by this invention. (A), (b) is a graph which shows an example of the relationship between the pulsation index | exponent and fuel injection quantity in one embodiment of the engine control apparatus by this invention, respectively. The graph which shows an example of pulsation existence determination in one embodiment of the engine control device by the present invention. The graph which shows an example of the relationship between the pulsation correction | amendment index | exponent and pulse width correction amount in one Embodiment of the engine control apparatus by this invention. The block diagram which shows the detail of other embodiment of the engine control apparatus by this invention. The flowchart showing the specific action | operation of other embodiment of the engine control apparatus by this invention. The graph which shows an example of the pulsation area | region-non-pulsation area | region setting in other embodiment of the engine control apparatus by this invention.

Explanation of symbols

100 Camshaft 101 Intake Pipe 102 Air Cleaner 103 Air Flow Meter (Air Flow Sensor)
104 Throttle sensor 105 Throttle body 106 Collector 107 In-cylinder injection internal combustion engine (engine)
DESCRIPTION OF SYMBOLS 108 Fuel tank 109 Fuel pump 110 Fuel pressure regulator 111 High pressure fuel pump 112 Injector 113 Ignition coil 114 Spark plug 115 Control unit 116 Cam angle sensor 117 Crank angle sensor 118 Air-fuel ratio sensor 121 Fuel pressure sensor 122 Cam shaft 123 Water temperature sensor 124 Electric motor 125 Fuel temperature sensor 126 Common rail 202 Injector control means 203 High pressure pump control means 211 Cam 212 Electromagnetic valve 213 Plunger 214 Pump chamber 215 Suction check valve 216 Discharge check valve 701 Injection amount calculation means 702 Pulse width calculation means 703 Injector drive control means 704 Discharge amount calculation means 705 Suction valve angle calculation means 706 High-pressure pump drive control means 707 Movement index calculation means 708 Pulsation detection means 709 Pulse width correction means 710 Fuel system abnormality determination means

Claims (10)

A high-pressure pump for boosting the fuel and discharging the fuel to the common rail; an injector for injecting the fuel stored in the common rail; and a fuel pressure sensor for measuring the pressure of the fuel stored in the common rail. A control device for an internal combustion engine that controls a pump and the injector based on a fuel pressure measurement value by the fuel pressure sensor,
A movement index calculating means for calculating a movement index representing a delay in fuel movement in the common rail based on the fuel injection amount of the injector;
Fuel injection amount correction means for correcting the fuel injection amount by the injector based on the movement index calculated by the movement index calculation means;
A control apparatus for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the movement index calculating means increases the movement index in accordance with an increase in a fuel injection amount of the injector.   The movement index calculating means increases the movement index when the temperature of the fuel in the common rail is lower than normal or when the fuel pressure of the common rail is lower than normal. 3. The control device for an internal combustion engine according to 2. Pulsation detecting means for determining the presence or absence of fuel pressure pulsation in the common rail based on a fuel pressure measurement value by the fuel pressure sensor;
The fuel injection amount correcting means corrects the fuel injection amount by the injector based on the presence or absence of fuel pressure pulsation determined by the pulsation detecting means in addition to the movement index calculated by the movement index calculating means. The control apparatus for an internal combustion engine according to any one of claims 1 to 3.   The pulsation detecting means determines that there is a fuel pressure pulsation when the change in fuel pressure measured by the fuel pressure sensor is greater than a predetermined threshold value, and determines that there is no fuel pressure pulsation otherwise. The control apparatus for an internal combustion engine according to claim 4.   6. The control apparatus for an internal combustion engine according to claim 5, wherein the pulsation detecting means increases the threshold value when the fuel pressure of the common rail is small.   The fuel injection amount correction means calculates a fuel injection correction amount based on the movement index calculated by the movement index calculation means, and performs fuel injection correction according to the presence or absence of fuel pressure pulsation determined by the pulsation detection means. The control method for an internal combustion engine according to any one of claims 4 to 6, wherein a calculation method of the amount is changed.    8. The control apparatus for an internal combustion engine according to claim 7, wherein the fuel injection amount correction means calculates a fuel injection correction amount with pulsation larger than that without pulsation.   The injector, the high-pressure pump, the fuel pressure sensor, and the common rail are configured by comparing a predetermined value that is predetermined based on the engine speed and the load with the fuel injection correction amount by the fuel injection amount correction means. 9. The control apparatus for an internal combustion engine according to claim 4, further comprising a fuel system abnormality determination unit that diagnoses abnormality of the fuel system to be performed and outputs a warning at the time of abnormality diagnosis.   The predetermined values of the fuel system abnormality determination means are individually determined for the engine speed and load region where the fuel pressure pulsation occurs and the engine speed and load region where the fuel pressure pulsation does not occur. The control device for an internal combustion engine according to claim 9, wherein the predetermined value is larger than a predetermined value in the non-pulsation region.

Images