JP2010138918A - Fuel injection control device for internal combustion engine, and method of controlling fuel injection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device for an internal combustion engine capable of securing startability, especially cold startability, in which a large quantity of fuel is injected at one time, to prevent deterioration of exhaust gas by accurately correcting the fuel injection quantity so that the fuel quantity actually supplied to the internal combustion engine coincides with a target value. <P>SOLUTION: Fuel injection quantity per unit time (actual fuel injection quantity QF) is computed in real time by using the fuel pressure in fuel injection, and the computed fuel injection quantity is integrated. The integrated fuel quantity (QFS) is compared with a target injection quantity (TQ), and the injection completion time is adjusted so that the actual fuel injection quantity and the target injection quantity accurately coincide with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device and a fuel injection control method for an internal combustion engine, and more particularly, to a fuel injection control device and a fuel injection control method for an internal combustion engine that inject fuel of a target fuel amount by a fuel injection valve. .

  Conventionally, many fuel injection devices used in internal combustion engines that use gasoline as fuel have used electromagnetic valves as fuel injection valves, and fuel pressurized by a fuel pump is opened in the internal combustion engine by opening the fuel injection valves. It is the composition which injects into. In this type of device, if the fuel pressure (fuel pressure) is constant, the fuel injection amount is proportional to the valve opening time of the fuel injection valve. The fuel injection amount is controlled by controlling according to the above.

  Here, since the correlation between the valve opening time of the fuel injection valve and the injection amount changes depending on the fuel pressure, when the fuel pressure changes, it is necessary to correct the valve opening time accordingly.

  The change in the fuel pressure occurs due to the difference between the amount of fuel supplied from the fuel pump and the amount of fuel injected from the fuel injection valve. In particular, in a cylinder injection internal combustion engine that injects fuel into the cylinder. Since the injection operation needs to be performed in a short time compared with the intake port injection type injection device, the fuel injection valve has a large injection amount per unit time, and the fuel pump is driven in synchronism with the rotation of the engine. Therefore, when the rotational speed is low, such as when the internal combustion engine is started, the amount of fuel supplied from the fuel pump is reduced, and the fuel pressure drop during fuel injection due to this becomes remarkable.

  For such a fuel pressure drop during fuel injection, the fuel pressure is sampled at two timings synchronized with the start and end of injection, and the actual fuel pressure drop is detected as the difference between the two, and this fuel pressure drop is supported. There has been proposed a fuel injection control device that learns a correction value and corrects an influence on a fuel injection amount due to a decrease in fuel pressure (for example, Patent Document 1).

JP-A-9-189255

  However, in the above-described conventional fuel injection control device, the correction value of the fuel injection amount is calculated at the end of the injection operation and correction is performed for the subsequent injections. Therefore, the injection amount is corrected from the first injection operation. It is impossible to implement. In addition, the accuracy of correction is low at a stage before sufficient learning is performed or when there is an uncertain factor in the change in fuel pressure.

  In addition, the fuel injected into the cylinder is not burned in a single combustion stroke, but a part of it adheres to the wall and is carried over to the next combustion stroke. Therefore, it is necessary to incorporate that amount of fuel into the next fuel injection amount calculation.

  However, the conventional fuel injection control device does not know the amount of fuel actually injected by the fuel injection valve, and performs the subsequent injection amount correction using only the past fuel pressure behavior. The amount of fuel carried over during the combustion stroke cannot be accurately grasped, and the calculation accuracy of the fuel injection amount deteriorates.

  If the fuel injection amount is not accurately corrected and the amount of fuel supplied to the internal combustion engine is different from the target value, startability may deteriorate or harmful substances in the exhaust gas may increase. is there.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to accurately correct the fuel injection amount so that the fuel amount actually supplied to the internal combustion engine becomes a target value. Another object of the present invention is to provide a fuel injection control device for an internal combustion engine that ensures startability, particularly cold startability with a large amount of fuel injection, and prevents deterioration of exhaust gas.

  In order to achieve the above object, a fuel injection control device for an internal combustion engine according to the present invention is a fuel injection control device for an internal combustion engine that injects fuel of a target fuel amount by a fuel injection valve. During the injection operation, the actual fuel amount injected from the fuel injection valve is calculated, and based on the actual fuel amount, the actual fuel injection amount by the fuel injection valve matches the target injection amount. The end timing of fuel injection by the fuel injection valve is adjusted.

  The fuel injection control device for an internal combustion engine according to the present invention preferably further calculates a total amount of the actual fuel amount at the end time of the adjusted fuel injection, and calculates a difference between the total amount of the actual fuel amount and the target injection amount. If there is, the next fuel injection amount is corrected using the difference.

  In order to achieve the above object, a fuel injection control device for an internal combustion engine according to the present invention is a fuel injection control device for an internal combustion engine that supplies a target amount of fuel by a fuel injection valve. During the fuel injection operation according to, an actual fuel amount per unit time injected from the fuel injection valve is calculated on the basis of the pressure of the fuel supplied to the fuel injection valve every unit time. The integrated injection amount is calculated by integration, the integrated injection amount is compared with the target injection amount, and the fuel injection by the fuel injection valve is matched so that the fuel injection amount by the fuel injection valve matches the target injection amount. Adjust the end time of.

  The fuel injection control device for an internal combustion engine according to the present invention preferably further calculates an integrated injection amount at the adjusted fuel injection end timing, and when there is a difference between the integrated injection amount and the target injection amount. The next fuel injection amount is corrected using the difference.

  More preferably, the fuel injection control device for an internal combustion engine according to the present invention further calculates an unburned fuel amount for each fuel injection, and corrects the next fuel injection amount using the unburned fuel amount.

  The fuel injection control device for an internal combustion engine according to the present invention preferably detects the pressure of the fuel supplied to the fuel injection valve by a pressure sensor installed in a pipe for supplying fuel to the fuel injection valve.

  In the fuel injection control device for an internal combustion engine according to the present invention, preferably, the pressure of the fuel supplied to the fuel injection valve is injected from the fuel injection valve and the discharge amount of the fuel pump that supplies the fuel to the fuel injection valve. Estimated using actual fuel amount.

In order to achieve the above object, a fuel injection control method for an internal combustion engine according to the present invention is a fuel injection control method for an internal combustion engine that supplies fuel of a target fuel amount by a fuel injection valve,
During the fuel injection operation by the fuel injection valve, the actual fuel amount injected from the fuel injection valve per unit time is calculated based on the pressure of the fuel supplied to the fuel injection valve every unit time. The fuel injection amount is calculated by calculating the integrated injection amount, comparing the integrated injection amount with the target injection amount, so that the fuel injection amount by the fuel injection valve matches the target injection amount. Adjust the end of fuel injection by the valve.

  According to the fuel injection control device for an internal combustion engine of the present invention, during the fuel injection operation by the fuel injection valve, the actual fuel amount injected from the fuel injection valve is calculated, and the fuel injection is based on the actual fuel amount. Since the fuel injection end time of the fuel injection valve is adjusted so that the actual fuel injection amount by the valve matches the target injection amount, the fuel is actually supplied to the internal combustion engine regardless of the fuel pressure change during the fuel injection process. The amount of fuel to be achieved becomes a target value or error is reduced, starting performance can be ensured, and exhaust gas deterioration can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows one Embodiment of the whole structure of the cylinder injection type internal combustion engine to which the fuel-injection control apparatus by this invention is applied. The block diagram which shows one Embodiment of the fuel system of the cylinder injection engine to which the fuel-injection control apparatus of the internal combustion engine by this invention is applied. The block diagram which shows one Embodiment of the high pressure fuel pump used for the engine fuel system with which the fuel-injection control apparatus of the internal combustion engine by this invention is applied. The block diagram of the engine control apparatus of the cylinder injection type internal combustion engine of this embodiment. The block diagram of the fuel-injection process by this embodiment. The time chart which shows the relationship between the injection operation | movement at the time of the fuel pressure fall in this embodiment, a fuel pressure change, and fuel injection amount. The time chart which shows the relationship between the injection operation | movement at the time of the fuel pressure rise in this embodiment, a fuel pressure change, and fuel injection amount. The time chart which shows the relationship between the injection operation | movement at the time of the fuel pressure rapid increase in this embodiment, a fuel pressure change, and fuel injection amount. The time chart which shows the relationship between the injection operation in the case of implementing injection operation in multiple times, a fuel pressure change, and fuel injection amount. The block diagram of the fuel-injection process by other embodiment of this invention.

  One embodiment of the overall configuration of a direct injection internal combustion engine to which a fuel injection control device according to the present invention is applied will be described with reference to FIG.

  The engine 1 is a multi-cylinder engine having a plurality of cylinders, and a piston 101a, a cylinder block 101b, and the like form a combustion chamber 101c having the number of cylinders.

  In each combustion chamber 101c, the air taken in from the inlet portion 102a of the air cleaner 102 has an intake air amount sensor (air flow sensor) 25, a throttle body 140 containing a throttle valve 140a for controlling the intake air amount, and a collector 106. As described above, the air is distributed and supplied by the intake pipe 107 connected to each combustion chamber 101c.

  The opening degree of the throttle valve 140a is controlled by the engine control device 90. The air flow sensor 25 outputs a signal representing the intake air amount to the engine control device 90. A throttle sensor 27 for detecting the opening degree of the throttle valve 140a is attached to the throttle body 140. The throttle sensor 27 outputs a signal representing the opening degree of the throttle valve 140a to the engine control device 90.

  Fuel such as gasoline is primarily pressurized from the fuel tank 50 by an electric fuel pump 51, regulated to a constant pressure (for example, 0.3 MPa) by a fuel pressure regulator 52, and further, a cam-driven high-pressure fuel pump 58. From the fuel injection valve 54 provided for each combustion chamber 101c via the common rail 53 that is a pipe that is secondarily pressurized to a high pressure (for example, 10 MPa) and supplies fuel to the fuel injection valve 54. Is injected into. The fuel injected into the combustion chamber 101 c forms an air-fuel mixture with the intake air, and is ignited by the spark plug 109 by an ignition signal that has been increased in voltage by the ignition coil 108.

  The common rail 53 detects the fuel pressure (fuel pressure) in the common rail 53 and outputs it to the engine control device 90. When the fuel pressure rises abnormally, the fuel in the common rail 53 is sent to the suction side of the high-pressure fuel pump 58. A relief valve 55 is provided for relief.

  A crank angle sensor 24 is attached to the crankshaft 101d of the engine 1. The crank angle sensor 24 outputs a signal indicating the rotational position of the crankshaft 101d to the engine control device 90. A cam angle sensor 117 is attached to the exhaust valve camshaft 120 for opening and closing the exhaust valve. The cam angle sensor 117 outputs an angle signal indicating the rotational position of the exhaust valve cam shaft 120 to the engine control device 90.

  The exhaust pipe 209 is provided with an air-fuel ratio sensor 208 that detects the oxygen concentration in the exhaust gas and outputs a detection signal to the engine control device 90, an exhaust gas purification catalyst 210, and the like.

  The common rail 53 is provided with a fuel pressure sensor 56 that detects the fuel pressure and outputs it to the engine control device 90, and a relief valve 55 that allows the fuel to escape to the input side of the high-pressure fuel pump when the fuel pressure rises abnormally.

  The overall configuration of the fuel system including the high-pressure fuel pump 58, the details of the high-pressure fuel pump 58, and FIGS. 2 and 3 will be described.

  The high pressure fuel pump 58 further pressurizes the fuel primarily pressurized by the fuel pump 51 and feeds it to the common rail 53. The fuel pump 51 has a cylinder chamber 7, a pump chamber 8, and a solenoid chamber 9. The cylinder chamber 7 is disposed below the pump chamber 8, and the solenoid chamber 9 is disposed on the suction side of the pump chamber 8.

  In the cylinder chamber 7, a plunger 2, a lifter 3, and a plunger lowering spring 4 are provided. The plunger 2 is reciprocally driven by the lifter 3 pressed against the pump drive cam 100 attached to the exhaust valve camshaft 120 of the engine 1 to change the volume of the pressurizing chamber 12.

  The pump chamber 8 includes a low-pressure fuel suction passage 10, a pressurization chamber 12, and a high-pressure fuel discharge passage 11.

  A suction valve 5 is provided between the suction passage 10 and the pressurizing chamber 12. The intake valve 5 is a check valve that is urged in the valve closing direction from the pressurizing chamber 12 side toward the intake passage 10 by the valve closing spring 5a and restricts the direction of fuel flow. The valve closing spring 5a is configured so that the pressure on the pressurizing chamber 12 side is equal to or higher than the pressure on the inflow passage 10 side across the suction valve 5 due to the volume change in the pressurizing chamber 12 by the plunger 2. When this occurs (during the discharge stroke), the suction valve 5 is urged to close.

  A discharge valve 6 is provided between the pressurizing chamber 12 and the discharge passage 11. The discharge valve 6 is a check valve that is urged in the valve closing direction from the discharge passage 11 side toward the pressurizing chamber 12 by the valve closing spring 6a and restricts the fuel flow direction, and is closed during the intake stroke. The valve is opened during the discharge stroke.

  The solenoid chamber 9 is provided with a solenoid 300 as an actuator, a suction valve engaging member 301, a valve opening spring 302, and a suction element 303.

  The suction valve engaging member 301 is disposed at a position opposite to the suction valve 5 and is in contact with the suction valve 5 at the tip thereof so as to be freely contactable and separable. When the solenoid 300 is energized, the valve opening spring It moves to the side of the suction element 303 (right side as viewed in FIG. 3) against the force of 302 and moves away from the suction valve 5 to allow the suction valve 5 to be closed by the spring force of the valve closing spring 5a. In contrast, when the solenoid 300 is de-energized, the suction valve engaging member 301 is moved to the position shown in FIG. 3 by the spring force of the valve opening spring 302 and pushes the suction valve 5 to close. The valve is forcedly opened against the spring force of the valve spring 5a.

  The fuel adjusted to a constant pressure from the fuel tank 50 through the fuel pump 51 and the fuel pressure regulator 52 is guided to the suction passage 10 of the pump chamber 8, and then the plunger 2 in the pressurizing chamber 12 in the pump chamber 8. The pressure is increased by the reciprocating motion, and is pumped from the discharge passage 11 of the pump chamber 8 to the common rail 53.

  In addition to each fuel injection valve 54 provided in accordance with the number of cylinders of the engine 1, a pressure adjustment valve (hereinafter referred to as a relief valve) 55 and a fuel pressure sensor 56 are attached to the common rail 53. The relief valve 55 is opened when the fuel pressure in the common rail 53 exceeds a predetermined value to prevent damage to the piping system.

  The operation of the high pressure fuel pump 58 will be described. As the pump drive cam 100 rotates, the plunger 2 moves from the top dead center side to the bottom dead center side according to the urging force of the plunger lowering spring 4, whereby the suction stroke of the pump chamber 8 is performed. In the intake stroke, the intake valve engaging member 301 is urged by the spring force of the valve opening spring 302 to engage with the intake valve 5 to open the intake valve 5, and the pressure is increased as the plunger 2 is lowered. The pressure in the pressure chamber 12 decreases, and fuel is sucked into the pressurizing chamber 12 from the suction passage 10.

  Next, when the plunger 2 moves from the bottom dead center side to the top dead center side against the biasing force of the plunger lowering spring 4 by the rotation of the pump drive cam 100, the compression stroke of the pump chamber 8 is performed. In the compression stroke, when the drive signal (ON signal) of the solenoid 300 as an actuator is output from the engine control device 90 and the solenoid 300 is energized (ON state), the intake valve engagement member 301 is attached to the valve opening spring 302. It moves in a direction away from the suction valve 5 against the force, the tip of the suction valve engaging member 301 is released from the engagement with the suction valve 5, and the suction valve 5 is thereby moved by the biasing force of the valve closing spring 5a. It moves in the valve closing direction, and the pressure in the pressurizing chamber 12 increases.

  When the suction valve engaging member 301 is most attracted to the suction element 303 side and the suction valve 5 synchronized with the reciprocation of the plunger 2 is closed and the pressure in the pressurizing chamber 12 is increased, The fuel presses the discharge valve 6. As a result, the discharge valve 6 is automatically opened against the urging force of the valve closing spring 6a, and high pressure fuel corresponding to the volume reduction of the pressurizing chamber 12 is discharged to the common rail 53 side.

  The drive signal of the solenoid 300 is turned off (OFF state) when the intake valve 5 is closed on the solenoid 300 side, but the pressure in the pressurizing chamber 12 is high as described above. The intake valve 5 is maintained in a closed state, and fuel is discharged to the common rail 53 side.

  When the plunger 2 moves from the top dead center side to the bottom dead center side according to the biasing force of the plunger lowering spring 4 by the rotation of the pump drive cam 100, the suction stroke of the pump chamber 8 is performed, and the pressurizing chamber 12 As the internal pressure decreases, the intake valve engaging member 301 is engaged with the intake valve 5 in accordance with the urging force of the valve opening spring 302 and moves in the valve opening direction, and the intake valve 5 is reciprocated by the plunger 2. The intake valve 5 is automatically opened in synchronization with the intake valve 5 and the open state is maintained. And since the pressure reduction has arisen in the pressurizing chamber 12, the discharge valve 6 is not opened. Thereafter, the above operation is repeated.

  Therefore, when the solenoid 300 is turned on during the compression stroke before the plunger 2 reaches the top dead center, the fuel is fed to the common rail 53 from this time, and the fuel is fed once. If it starts, the pressure in the pressurizing chamber 12 rises. Therefore, even if the solenoid 300 is turned off thereafter, the suction valve 5 remains closed, but automatically in synchronism with the start of the suction stroke. The valve can be opened, and the amount of fuel discharged to the common rail 53 can be adjusted by the output timing of the ON signal of the solenoid 300. Furthermore, the pressure of the common rail 53 can be feedback controlled to the target value by calculating an appropriate energization ON timing by the engine control device 90 based on the signal of the fuel pressure sensor 56 and controlling the solenoid 300.

  As shown in FIG. 4, the engine control device 90 is a microcomputer type composed of an MPU 203, an EP-ROM 202, a RAM 204, an I / O-LSI 201 including an A / D converter, and the like. A fuel injection control device is realized by the processing.

  The engine control device 90 includes a crank angle sensor 24, a cam angle sensor 117, a water temperature sensor 28 that measures the engine coolant temperature, an air flow sensor 25, an intake pipe internal pressure sensor 29 that measures the pressure in the intake pipe, a throttle sensor 27, and a fuel pressure sensor. 56, taking signals from various sensors including the air-fuel ratio sensor 208 as input, executing predetermined calculation processing, outputting various control signals calculated as the calculation results, and a fuel pump 51 as an actuator; A predetermined control signal is output to the high-pressure fuel pump 58, the fuel injection valve 54, the ignition coil 108, etc., and fuel discharge amount control, fuel injection amount control, ignition timing control, and the like are executed.

  Next, the fuel injection process in the engine control apparatus 90 will be described with reference to FIG. The engine control device 90 includes an engine speed NE calculation processing unit 501, a basic injection amount TP calculation processing unit 502, an operating condition determination unit 503, an air-fuel ratio feedback control unit 504, a fuel pressure correction control unit 506, a fuel injection A control unit 508 and multiplication processing units 505 and 507 are included.

  The engine speed NE calculation processing unit 501 calculates the engine speed (rotational speed) NE from the input of the crank angle sensor 24. The basic injection amount TP calculation processing unit 502 calculates the basic fuel injection amount TP by using the intake air amount QA by the air flow sensor 25 and the engine speed NE.

  The operating condition determination unit 503 uses the engine speed NE, the basic fuel injection amount TP, the coolant temperature TW by the water temperature sensor 28, the intake pipe internal pressure PA by the intake pipe internal pressure sensor 29, the throttle opening TR by the slot sensor 27, and the like. 1 is determined, and a fuel correction amount KMR optimum for the operation condition is calculated.

  The air-fuel ratio feedback control unit 504 calculates an air-fuel ratio feedback correction coefficient RMD using the output of the air-fuel ratio sensor 208.

  Multiplication processor 505 multiplies basic fuel injection amount TP by fuel correction amount KMR and air-fuel ratio feedback correction coefficient RMD to calculate final fuel injection amount (target fuel amount) TQ.

  In order to calculate the time TF for opening the fuel injection valve 54 from the final fuel injection amount TQ, it is necessary to obtain an actual fuel amount (injected actual fuel amount) QF injected from the fuel injection valve 54 per unit time. Since the actual fuel injection quantity QF per unit time varies depending on the fuel pressure PF, it can be expressed as the following formula (1).

QF = A√PF (1)
Here, A is a number obtained from the area of the nozzle of this fuel injection valve 54 and the outflow coefficient, and it is assumed that the area of the nozzle, the mass and viscosity of the fuel are constant, and A is treated as a constant.

  From equation (1), it can be seen that the actual fuel injection amount QF per unit time injected from the fuel injection valve 54 is proportional to the square root of the fuel pressure PF. Therefore, the fuel pressure correction control unit 506 uses the fuel pressure PF to determine the fuel pressure. The correction value KPF is calculated by the following formula (2).

KPF = 1 / B {√ (PS / PF)} (2)
Here, B and PS are constants obtained from the characteristics of the fuel injection valve 54. These constants set the reference fuel pressure as PS, in which case the amount of fuel injected per unit time is B. Can be obtained from

  The multiplication processing unit 507 calculates the injection time TF by multiplying the final fuel injection amount TQ by the fuel pressure correction value KPF.

  The fuel injection control unit 508 opens the fuel injection valve 54 in accordance with the intake stroke or compression stroke of each cylinder, starts fuel injection, and then closes the fuel injection valve 54 when the injection time TF elapses. End injection.

FIG. 6 shows the relationship between the injection valve operation, the fuel pressure change, and the fuel injection amount when the fuel pressure is reduced.
The opening / closing timing of the fuel injection valve 54 is controlled by a timer function (not shown) in the MPU 203. When the MPU 203 performs software processing and instructs the timer function to open / close the fuel injection valve 54, the timer function is instructed. The opening / closing control of the fuel injection valve 54 is performed at the timing.

  Specifically, in the timer function, the timer counter TM is added at a predetermined cycle, and the comparison with the compare register CR is always performed. When the value of the timer counter TM becomes equal to the value of the compare register CR, the timer function generates a compare match signal, controls the output port of the MPU 203 in synchronization with the compare match signal, and opens and closes the fuel injection valve 54.

  First, the calculation of the injection start timing T0 and the injection time TF is performed before the start of injection, and the value of T0 is set in the compare register CR. Thereafter, when time elapses and the timer counter TM becomes equal to the value of the compare register CR, injection is started at the timing T0.

  Simultaneously with the start of injection, the injection time TFA is calculated using the fuel pressure PF and the final fuel injection amount TQ at that time, and the value of T0 + TFA is set in the compare register CR. Further, from the fuel pressure PF at the timing of T0, the actual injection fuel quantity QF per unit time is calculated using Equation (1), and this is stored as QF0.

  At timing Tn (n = 1, 2, 3,...) After T1, the actual fuel pressure PF at that time, that is, from the fuel pressure PF at that time, from the fuel pressure PF at that time, the actual injection fuel per unit time using Equation (1) The amount QF is calculated and stored as QFn, and the integrated injection amount QFS is calculated by the following equation (3) every unit time, that is, every time the injection actual fuel amount QF is calculated, and this is calculated as QFSn. Remember.

_{QFS = QFS n-1 + {} (QF n-1 + QF n) (T n -T n-1) / 2} ... (3)
Equation (3) represents the cumulative injection amount QFS is the time integral of the injection actual fuel quantity QF of each unit time, QFn the upper base, a lower base and QF _n-1, the height T _n -T _n-1 represents that the area of the trapezoid is integrated.

  Every time the integrated injection amount QFS is calculated, the integrated injection amount QFS is subtracted from the final fuel injection amount TQ to calculate the remaining injection amount QFR.

  After calculating the remaining injection amount QFR, the fuel pressure correction value KPF at the timing of Tn is multiplied by this to calculate the injection end time TFn corresponding to the remaining injection amount, and the value of Tn + TFn is set in the compare register CR The injection end time is updated every time the remaining injection amount QFR is calculated.

  Thereafter, when time elapses and the timer counter TM becomes equal to the value of the compare register CR, the injection is terminated at the timing of Tn + TFn.

  The process executed at the timing of Tn is repeated at a cycle shorter than the injection time TF because the error between the target fuel injection amount and the actual fuel injection amount can be reduced as the repetition cycle is shorter and the number of times is increased. It is performed during the scheduled time of software and the free time of software processing.

  The processing when the fuel pressure is reduced has been described above. As shown in FIG. 7, this control is effective without any change even when the fuel pressure is increased. When the fuel pressure rises, the cumulative injection amount QFS increases faster than when the fuel pressure is constant due to the fuel pressure rise, so the actual injection time is corrected to be shortened.

  However, when the fuel pressure suddenly increases greatly, the cumulative injection amount QFS exceeds the final fuel injection amount TQ, which is the target value of the injection amount, when performing the process of updating the injection end time at the timing of Tn. May end up. Processing in this case will be described with reference to FIG.

  Since the fuel pressure has not yet increased at the timing of T1, there is no change in the injection end timing, but immediately after the timing of T1 has elapsed, the fuel pressure rapidly increases, and at the timing of T2, the cumulative injection amount QFS is the final fuel injection amount. The TQ has been exceeded. When the cumulative injection amount QFS becomes equal to or greater than the final fuel injection amount TQ, an instruction is given to the timer function to immediately end the fuel injection as an exception process. Thereby, the excessive injection amount can be minimized.

  As described above, the fuel injection control unit 508 calculates the actual fuel amount injected from the fuel injection valve 54 during the fuel injection operation by the fuel injection valve 54, and based on the actual fuel amount, the fuel injection valve 54. The end timing of fuel injection by the fuel injection valve 54 is adjusted so that the actual fuel injection amount according to the above matches the final fuel injection amount (target fuel amount) TQ.

  More specifically, the fuel injection control unit 508 performs the actual fuel injection per unit time based on the pressure (fuel pressure PF) of the fuel supplied to the fuel injection valve 54 during the fuel injection operation by the fuel injection valve 54. An amount QF is calculated and integrated to calculate an integrated injection amount QFS. The integrated injection amount QFS is compared with the final fuel injection amount (target fuel amount) TQ, and the actual fuel injection amount by the fuel injection valve 54 is determined. The end timing of fuel injection by the fuel injection valve 54 is adjusted so as to coincide with the target injection amount.

  In this way, during the fuel injection, the actual injected fuel amount QF that is actually injected is calculated from the fuel pressure PF at every unit time, and the target fuel amount and the fuel amount actually injected from the fuel injection valve 54 are calculated. Since the closing timing of the fuel injection valve 54 is adjusted so as to be equal to each other, it is possible to immediately adjust the injection time with respect to the fuel pressure change during the fuel injection operation, and it is difficult to predict the fuel pressure change at the first The end timing of the injection operation is adjusted so that the target fuel amount and the actual fuel amount are equal even during injection or when a fuel pressure change due to an uncertain factor occurs. As a result, regardless of the fuel pressure change during the fuel injection process, the amount of fuel actually supplied to the internal combustion engine becomes the target value or error is reduced, ensuring startability, particularly low temperature startability, and exhaust gas. Deterioration can be prevented.

  When the fuel injection operation is performed a plurality of times, the actual fuel amount injected from the fuel injection valve 54 during the previous injection operation is calculated, and the target fuel amount and the actual fuel amount at the previous injection operation are calculated. The next target fuel amount can be corrected using the difference.

  An embodiment of fuel injection amount correction when the injection operation is performed a plurality of times will be described with reference to FIG. Here, although the case where the injection operation is performed twice will be described, the control of the embodiment described with reference to FIGS. 6 to 8 is performed for each individual injection operation.

  In other words, during fuel injection, the actual fuel amount QF per unit time, the cumulative injection amount QFS, the remaining injection amount QFR, and the injection end time TFn are calculated, and the value of Tn + TFn is set in the compare register CR to end the injection. Update the time.

  Here, in the present embodiment, the actual fuel amount QF, the integrated injection amount QFS, and the remaining injection amount QFR per unit time are calculated even at the timing of the end of injection (actual), and stored as QFZ, QFSZ, and QFRZ, respectively. .

  In FIG. 9, as shown in the first injection, when the fuel pressure suddenly decreases immediately after the timing T1, the injection ends when the remaining injection amount QFR is not less than 0, that is, adjusted. If there is a difference between the total amount of actual fuel at the end of fuel injection, in other words, the cumulative injection amount QFSZ and the target fuel amount (final fuel injection amount TQU), The injection time is calculated using the remaining injection amount QFRZ at the time of the previous injection.

The calculation of the injection time performed for the second injection will be described with reference to FIG.
The processing block diagram shown in FIG. 10 is obtained by adding an unburned correction amount QUB calculation processing unit 509 to the processing block diagram shown in FIG.

  The unburned correction amount QUB calculation processing unit 509 calculates the intake air amount QA, the rotational speed NE, the fuel injection amount TQ, the cooling water temperature TW, the intake pipe pressure PA, the throttle opening TR, the remaining injection amount QFRZ at the previous injection, and the like. Use to calculate the unburned correction amount QUB.

  The unburned correction amount is a correction value for the amount of fuel that does not burn during the cycle of the fuel injected from the fuel injection valve 54 into the combustion chamber 101c, and the amount of fuel that adheres to the combustion chamber wall without being vaporized. The amount of fuel that is vaporized but is not burned and that remains unburned and is corrected as the injection amount.

  Specifically, the fuel volatilization characteristics with respect to the temperature calculated by the cooling water temperature TW, and the fuel volatilization characteristics with respect to the air flow rate calculated by the intake air amount QA, the rotational speed NE, the intake pipe internal pressure PA, the throttle opening TR, and the like. Are set in advance, and for each environment, the ratio of the injected fuel to the combustion chamber wall without vaporization (adhesion rate RW) and the ratio of remaining vaporized while burning (incombustibility RM) And the amount of unburned fuel in this cycle is obtained by multiplying the fuel injection amount TQ by the adhesion rate RW and the incombustibility rate RM.

  Most of the fuel adhering to the combustion chamber wall in the previous cycle is carried over to the next cycle, and part of it is vaporized and combusted in that cycle, so the unburned correction amount QUB is the unburned amount of this cycle. This is calculated by subtracting the amount of fuel vaporized in the previous cycle from the fuel amount. Therefore, in order to accurately calculate the unburned correction amount QUB, it is necessary to accurately grasp the amount of fuel actually injected in the previous cycle.

  In the present embodiment, the unburned correction amount QUB calculation processing unit 509 obtains an adhesion amount subtraction value QFRP by multiplying the remaining injection amount QFRZ at the previous injection by the adhesion rate RW, and from the amount of fuel adhered in the previous cycle. Thus, when the injection amount in the previous cycle is less than the initial assumption, the unburned correction amount QUB is calculated based on the actual injection amount in the next cycle. Become so.

  Based on the above, the second injection time in FIG. 9 will be described. Since the remaining injection amount QFRZ at the time of the previous injection is a value larger than 0, the remaining injection amount at the injection start timing of the second injection. The adhesion amount subtraction value QFRP is obtained by multiplying QFRZ by the adhesion rate RW, and the unburned fuel correction amount QUB is increased by that amount. By the addition processing unit 510 adding the unburned fuel correction amount QUB, the final fuel injection The quantity TQU has increased.

  As described above, in the present embodiment, the total amount of the actual fuel amount (integrated injection amount QFSZ) at the adjusted fuel injection end timing is calculated, and the total amount of the actual fuel amount and the final fuel injection amount TQU (target injection amount). ), The next fuel injection amount is corrected using the difference.

  Specifically, the integrated injection amount QFSZ at the adjusted fuel injection end timing is calculated, and when there is a difference between the integrated injection amount QFSZ and the final fuel injection amount TQU (target injection amount), the difference is used. Correct the next fuel injection amount.

  Therefore, in the present embodiment, the air-fuel ratio for each cycle can be more reliably maintained at the target value, and startability and exhaust gas deterioration can be prevented.

  Further, the remaining injection amount QFRZ at the time of the previous injection and the unburned fuel amount in the previous cycle (unburned correction amount QUB) are calculated according to the operating state of the internal combustion engine, and the next time using the unburned fuel amount. Therefore, the air-fuel ratio can be maintained at the target value in consideration of the unburned fuel amount, and the exhaust gas can be further prevented from deteriorating.

  In the above-described embodiment, the fuel pressure measurement value by the fuel pressure sensor 59 is used as the fuel pressure PF of the common rail 53. However, it can be calculated from the volume of fuel flowing into the common rail 53 and the volume of fuel flowing out.

  When the volume of fuel flowing into the common rail 53 is QIN and the volume of fuel flowing out is QOUT, the fuel pressure PF of the common rail 53 is calculated by the following equation (4).

PF = {(QIN−QOUT) / VR} KC (4)
In Equation (4), VR is the volume of the common rail 53, and KC is the elastic coefficient of the common rail 53.

  Therefore, if QIN and QOUT before the engine 1 starts rotating are set to 0, the fuel pressure PF also becomes 0. Here, since QIN is an integrated value of the fuel discharge amount of the high-pressure fuel pump 58 and QOUT is an integrated value of the fuel injection amount, the fuel pressure PF can be calculated by obtaining these values.

  Specifically, QIN is obtained by multiplying the cross-sectional area of the plunger 2 in the high-pressure fuel pump 58 by the stroke amount and the number of strokes of the plunger 2, and these are calculated from the rotation speed of the engine 1 and the output timing of the solenoid 300. be able to. QOUT can be calculated by integrating the integrated injection amount QFS in the above-described embodiment.

  As described above, the fuel pressure PF can be calculated without using the fuel pressure sensor 56, and the portion using the fuel pressure sensor 56 in the above-described embodiment can be replaced. By eliminating the fuel pressure sensor 56, the cost can be reduced by simplifying the engine system.

The effects of the fuel injection control device according to the present embodiment can be summarized as follows.
(1) Since the actual fuel amount is calculated during the fuel injection operation and the injection end timing is adjusted, the injection time can be immediately adjusted with respect to the fuel pressure change during the fuel injection operation, and the fuel pressure change is predicted. Even when the initial injection is difficult or when the fuel pressure changes due to uncertain factors, the end timing of the injection operation is adjusted so that the target fuel amount and the actual fuel amount are equal, ensuring startability, Exhaust gas deterioration can be prevented.

(2) The total amount of the actual fuel amount at the end time of the adjusted fuel injection is calculated, and when there is a difference between the total amount of the actual fuel amount and the target injection amount, the next fuel is calculated using the difference. By correcting the injection amount, that is, calculating the integrated injection amount at the end time of the adjusted fuel injection, if there is a difference between the integrated injection amount and the target injection amount, the difference is used for the next time. By correcting the fuel injection amount of the fuel, the air-fuel ratio for each cycle can be maintained at the target value more reliably, and the fuel actually supplied to the internal combustion engine regardless of the fuel pressure change during the fuel injection process The amount becomes a target value or error is reduced, and startability and deterioration of exhaust gas can be prevented.

(3) The actual fuel injection amount history is calculated by calculating the unburned fuel amount in the previous cycle according to the operating state of the internal combustion engine and correcting the next fuel injection amount using the unburned fuel amount. Makes it possible to accurately grasp the amount of fuel that has been carried over to the present time without being able to burn, and can maintain the air-fuel ratio at the target value, ensuring startability and deteriorating exhaust gas. Can be prevented.

(4) Since the fuel pressure is measured using the fuel pressure sensor, it is possible to accurately calculate the injection amount.
(5) When estimating the pressure of the fuel supplied to the fuel injection valve by using the discharge amount of the fuel pump that supplies the fuel to the fuel injection valve and the actual fuel amount injected from the fuel injection valve Since the fuel pressure is calculated without using the fuel pressure sensor, the apparatus can be simplified and the cost can be reduced.

1 Engine 5 Suction valve 5a Valve closing spring 6 Discharge valve 6a Valve closing spring 7 Cylinder chamber 8 Pump chamber 9 Solenoid chamber 10 Suction passage 11 Discharge passage 12 Pressurization chamber 24 Crank angle sensor 25 Suction air amount sensor (air flow sensor)
27 Throttle sensor 28 Water temperature sensor 29 Intake pipe internal pressure sensor 50 Fuel tank 51 Fuel pump 52 Fuel pressure regulator 53 Common rail 54 Fuel injection valve 55 Relief valve 56 Fuel pressure sensor 58 High pressure fuel pump 90 Engine control device 100 Pump drive cam 101a Piston 101b Cylinder block 101c Combustion chamber 101d Crankshaft 102 Air cleaner 106 Collector 107 Intake pipe 108 Ignition coil 109 Spark plug 117 Cam angle sensor 120 Exhaust valve camshaft 140 Throttle body 140a Throttle valve 202 EP-ROM
203 MPU
204 RAM
208 Air-fuel ratio sensor 209 Exhaust pipe 210 Exhaust gas purification catalyst 300 Solenoid 301 Suction valve engagement member 302 Valve opening spring 501 Engine speed NE calculation processing unit 502 Basic injection amount TP calculation processing unit 503 Operating condition determination unit 504 Air-fuel ratio feedback Control unit 505 Multiplication processing unit 506 Fuel pressure correction control unit 507 Multiplication processing unit 508 Fuel injection control unit 509 Unburnt correction amount QUB calculation processing unit 510 Addition processing unit

Claims (8)

A fuel injection control device for an internal combustion engine that supplies a target amount of fuel by a fuel injection valve,
During the fuel injection operation by the fuel injection valve, an actual fuel amount injected from the fuel injection valve is calculated, and based on the actual fuel amount, the actual fuel injection amount by the fuel injection valve becomes the target injection amount. A fuel injection control device for an internal combustion engine, wherein an end timing of fuel injection by the fuel injection valve is adjusted so as to match.   When the total amount of the actual fuel amount at the end time of the adjusted fuel injection is calculated and there is a difference between the total amount of the actual fuel amount and the target injection amount, the next fuel injection amount is calculated using the difference. The fuel injection control device for an internal combustion engine according to claim 1, wherein correction is performed. A fuel injection control device for an internal combustion engine that supplies a target amount of fuel by a fuel injection valve,
The actual fuel per unit time injected from the fuel injector per unit time based on the pressure of the fuel supplied to the fuel injector per unit time during the fuel injection operation by the fuel injector An amount is calculated, integrated to calculate an integrated injection amount, the integrated injection amount is compared with the target injection amount, and the fuel injection amount by the fuel injection valve matches the target injection amount. A fuel injection control device for an internal combustion engine, wherein the fuel injection end time of the fuel injection valve is adjusted.   An integrated injection amount at the end timing of the adjusted fuel injection is calculated, and when there is a difference between the integrated injection amount and the target injection amount, the next fuel injection amount is corrected using the difference. A fuel injection control device for an internal combustion engine according to claim 3.   5. The fuel injection control for an internal combustion engine according to claim 2 or 4, wherein an unburned fuel amount is calculated for each fuel injection, and the next fuel injection amount is corrected using the unburned fuel amount. apparatus.   6. The pressure of the fuel supplied to the fuel injection valve is detected by a pressure sensor installed in a pipe that supplies fuel to the fuel injection valve. 6. A fuel injection control device for an internal combustion engine.   The pressure of the fuel supplied to the fuel injection valve is estimated using a discharge amount of a fuel pump that supplies fuel to the fuel injection valve and an actual fuel amount injected from the fuel injection valve. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 5. A fuel injection control method for an internal combustion engine that supplies fuel of a target fuel amount by a fuel injection valve,
During the fuel injection operation by the fuel injection valve, the actual fuel amount injected from the fuel injection valve per unit time is calculated based on the pressure of the fuel supplied to the fuel injection valve every unit time. The fuel injection amount is calculated by calculating the integrated injection amount, comparing the integrated injection amount with the target injection amount, so that the fuel injection amount by the fuel injection valve matches the target injection amount. A fuel injection control method for an internal combustion engine, characterized in that an end timing of fuel injection by a valve is adjusted.

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