JP2013137028A - Device and method for fuel injection control of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain and improve the precision of a fuel injection amount, even if a current waveform or a current value supplied to a fuel injection valve is changed to extend a dynamic range of the fuel injection valve.SOLUTION: A correction time for correcting an opening/closing delay of the fuel injection valve is variably set by a valve-response-delay-time calculating part 103 and a selector part 106 in accordance with a setting change in the current waveform and the current value.

Description

  The present invention relates to a fuel injection control device and method for an internal combustion engine, and more particularly to a fuel injection control device and control method for correcting opening and closing delays of a fuel injection valve.

  A fuel injection internal combustion engine performs a calculation for converting a fuel amount determined according to an operating state into an injection time of a fuel injection valve, and controls the drive of the fuel injection valve in accordance with the injection time Thus, the fuel supply amount is controlled.

  The fuel injection valve is of an electromagnetic type, and fuel is injected by opening a valve body by a magnetic force generated by a current flowing through an internal solenoid (electromagnetic coil). The amount of fuel injected by the fuel injection valve is mainly the difference between the pressure of the fuel and the atmospheric pressure at the injection port of the fuel injection valve, and the fuel is injected while maintaining the valve body open. Determined by time.

  In recent years, from the viewpoint of reducing fuel consumption, there has been a demand for a reduction in the idling speed of an internal combustion engine, and accordingly, there is an increasing demand for minimizing the amount of fuel that can be injected by a fuel injection valve. There is a tendency. Similarly, in order to reduce fuel consumption, when the output of the internal combustion engine is unnecessary, the opportunity to perform fuel cut that does not perform fuel injection increases, and the frequency of restarting fuel injection also increases. When resuming fuel injection, it is necessary to inject a small amount of fuel corresponding to no load. Further, split injection is performed for the purpose of increasing output and improving exhaust performance. This is intended to improve the performance of the internal combustion engine by dividing the fuel originally required for one injection into a plurality of times and injecting the fuel at an appropriate time. It is requested to do.

  In internal combustion engines, attempts have been made to improve fuel consumption when mounted on vehicles by downsizing. In this case, since the specific output is required to be improved by supercharging or the like, it is required to increase the maximum injection amount without increasing or decreasing the minimum injection amount of the fuel injection valve.

  Therefore, the dynamic range (a value obtained by dividing the maximum injection amount by the minimum injection) required for the fuel injection valve of the internal combustion engine tends to increase.

  As a prior art of the fuel injection control device, it is determined whether or not the effective minimum pulse width characteristic (Qmin characteristic) of the fuel injection amount is an important region in the operating state of the internal combustion engine, and a small current value of a plurality of different current waveforms is maintained. By switching and supplying one of the currents, the fuel injection valve can be optimally controlled even at high fuel pressures when the solenoid inductance of the fuel injection valve is small due to the miniaturization of the fuel injection valve. Those that can maintain the quantity characteristics well are known (for example, see Patent Document 1).

  Further, as a prior art of a fuel injection control device, fuel injection is performed based on outputs from a water temperature sensor for detecting the temperature of engine cooling water, an intake negative pressure sensor, an atmospheric temperature sensor, an atmospheric pressure sensor, and a battery voltage of an in-vehicle battery. An injection time calculating means for calculating the injection timing and the injection time of the valve; a correction coefficient generating means for generating a correction coefficient based on the battery voltage of the in-vehicle battery; and a correction coefficient output from the correction coefficient generating means. Fuel injection valve opening delay time correcting means for correcting the fuel injection valve opening delay time, fuel injection valve closing delay time correcting means for correcting the fuel injection valve closing delay time, and fuel injection valve opening delay time Injection time correcting means for correcting the injection time of the fuel injection valve based on the output from the correcting means and the output from the fuel injection valve closing delay time correcting means; The fuel injection valve over a wide range from the time of high rotation and high load until low rotation and low load which can improve the emission fuel are known (e.g., see Patent Document 2).

Japanese Patent No. 4037632 Japanese Patent No. 3917714

  In order to accurately inject an appropriate amount of fuel from the fuel injector, it is necessary to set a time for maintaining the opening of the fuel injector according to the fuel pressure and to quickly open and close the fuel injector. On the other hand, when the fuel injection valve opens and closes, the fuel injection control device delays from the time when the fuel injection control device truly opens and closes due to the response delay of the current circuit and the fuel injection valve. Is completed.

  With respect to the valve opening delay, it is possible to avoid the injection amount from deviating from a desired value by setting the time obtained by adding the time for correcting the valve opening delay as the energization time for the fuel injection valve in advance. For the valve closing delay, if the energization time for the fuel injection valve is long, the time obtained by subtracting the time for correcting the valve closing delay in advance is set as the energization time for the fuel injection valve. The amount can be prevented from deviating from a desired value.

  However, if the fuel injection amount is small and the energization time to the fuel injection valve is short, the energization time after subtracting the valve closing delay time will cause the fuel injection valve to close before it opens sufficiently. Therefore, the required injection amount cannot be accurately injected.

  On the other hand, when the fuel injection amount to the internal combustion engine is small and the energization time is short, the valve closing delay is reduced by changing the waveform of the current supplied to the fuel injection valve or the magnitude of the current value. Therefore, it is possible to avoid a short energization time such that the fuel injection valve closes before the fuel injection valve is sufficiently opened.

  In-cylinder direct injection internal combustion engines are in a high-load operating range, and when it is necessary to supply a large amount of fuel from the fuel injection valve, there is an upper limit on the time that can be injected, so the fuel pressure is increased. It is necessary to shorten the energization time. When the fuel pressure is increased, the force for closing the fuel injection valve is increased, and the driving force necessary for opening the fuel injection valve is increased accordingly, so that the valve opening delay is increased. In addition, due to manufacturing variations of the fuel injection valve, it is assumed that the fuel injection valve closes unintentionally during the energization time when it is desired to keep the fuel injection valve open.

  In order to avoid this phenomenon, when the fuel pressure of the internal combustion engine is high, it is conceivable that the current waveform supplied to the fuel injection valve is changed, for example, the valve opening current or the holding current value is made larger than usual.

  On the other hand, since the current supplied to the fuel injection valve is supplied from the power supply via the fuel injection control device, from the viewpoint of reducing heat generation and fuel consumption of the fuel injection valve and fuel injection control device, the fuel injection valve It is necessary to make the current value of the current supplied to the valve as small as possible.

  In the fuel injection control device that can change the current waveform and current value supplied to the fuel injection valve, the contradiction can be solved by changing the current waveform and current value in accordance with the operating region of the internal combustion engine. In other words, change to a large current value only in an operating region where a large current is required for the fuel injection valve, and in a normal region, an operating region where it is necessary to supply a necessary and sufficient current lower than that to reduce the minimum injection amount. Then, by changing to an appropriate current waveform, it is possible to achieve both injection characteristics required for the fuel injection valve and heat generation reduction.

  However, if the waveform of the current supplied to the fuel injection valve or the magnitude of the current value is changed, the degree of valve opening delay and valve closing delay changes, and the same correction time as before the change is made. If the energization time is left as it is, a deviation from the desired fuel injection amount may occur, and the required injection amount control accuracy may not be maintained. On the other hand, the above-described prior art cannot sufficiently meet the demand for such fuel injection amount accuracy.

  An object of the present invention is to provide a fuel injection control capable of maintaining and improving the fuel injection amount accuracy even if the current waveform or current value supplied to the fuel injection valve is changed in order to expand the dynamic range of the fuel injection valve. It is to provide an apparatus and method.

  In order to achieve the above object, a fuel injection control device for an internal combustion engine according to the present invention converts an injection amount of fuel supplied to the internal combustion engine into a valve opening time of an electromagnetic fuel injection valve, and opens the fuel injection valve. A fuel injection control device for an internal combustion engine that calculates a valve closing delay as a correction time, corrects the valve opening time by the correction time, controls an energization time of the fuel injection valve, and controls a fuel injection amount; , A current waveform / current set value changing means capable of changing the setting of at least one of the current waveform or current value of the current supplied to the fuel injection valve, and a current waveform and current by the current waveform / current set value changing means Valve response delay time calculating means for variably setting the correction time for correcting the opening and closing delays of the fuel injection valve in accordance with a change in the value setting.

  In order to achieve the above object, a fuel injection control method for an internal combustion engine according to the present invention converts an injection amount of fuel supplied to the internal combustion engine into a valve opening time of an electromagnetic fuel injection valve, and A fuel injection control method for an internal combustion engine that calculates a delay in opening and closing the valve as a correction time, controls the energization time of the fuel injection valve by correcting the valve opening time by the correction time, and controls a fuel injection amount. The correction time for correcting the delay in opening and closing of the fuel injection valve is changed in accordance with a change in the setting of at least one of the current waveform or current value of the current supplied to the fuel injection valve.

  According to the fuel injection control device and method for an internal combustion engine according to the present invention, the correction time for correcting the delay in opening and closing the fuel injection valve in accordance with the change in the setting of the current waveform or current value of the current supplied to the fuel injection valve Therefore, even if the current waveform or current value supplied to the fuel injection valve is changed in order to expand the dynamic range of the fuel injection valve, the fuel injection amount accuracy is maintained and improved.

The block diagram of the internal combustion engine system carrying the fuel-injection control apparatus by embodiment of this invention. The circuit diagram which shows the structure of the fuel-injection control apparatus by embodiment of this invention. The timing chart which shows the relationship between the exciting current which flows through the electromagnetic coil of a fuel injection valve, and the on-off valve of the valve body of a fuel injection valve. The timing chart which shows the electricity supply control of the fuel injection valve by the fuel-injection control apparatus of this embodiment. The timing chart which shows about improvement of the exciting current which flows into the electromagnetic coil of a fuel injector, and the valve closing delay of a fuel injector when the drive pulse width of a fuel injector is small. The timing chart which shows about the improvement of the response delay of the fuel injection valve 5 by the excitation current which flows into the electromagnetic coil of a fuel injection valve, and high pressure of fuel pressure. The graph which shows the fuel-injection characteristic at the time of changing and changing the waveform of the electric current supplied to the electromagnetic coil of a fuel-injection valve by the fuel-injection control apparatus by embodiment. The block diagram which shows the detail of the fuel-injection control apparatus of this embodiment. The block diagram of the principal part of the fuel-injection control apparatus of this embodiment. The flowchart which shows the processing flow which calculates the energization time to a fuel injection valve in the fuel-injection control apparatus by embodiment of this invention. In the fuel injection control device according to the present embodiment, a timing chart showing an excitation current flowing through a fuel injection valve when a high voltage power supply fails.

Hereinafter, the configuration and operation of the fuel injection control apparatus according to the embodiment of the present invention will be described with reference to FIGS.
First, the configuration of an internal combustion engine system equipped with the fuel injection control apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of an internal combustion engine system equipped with a fuel injection control device according to a first embodiment of the present invention.

  The internal combustion engine (engine) 1 includes a piston 2, an intake valve 3, and an exhaust valve 4. The intake air passes through an air flow meter (AFM) 20, the flow rate of which is adjusted by a throttle valve 19, and is supplied from a collector 15, which is a branching portion, to the combustion chamber 21 of the engine 1 through the intake pipe 10 and the intake valve 3. . The fuel is supplied from the fuel tank 23 to the high-pressure fuel pump 25 by the low-pressure fuel pump 24, and is increased to a pressure necessary for fuel injection by the high-pressure fuel pump 25. The fuel boosted by the high-pressure fuel pump 25 is directly injected and supplied from the fuel injection valve 5 to the combustion chamber 21 of the engine 1 and ignited by the ignition coil 7 and the spark plug 6. The pressure of the fuel supplied to the fuel injection valve 5 is measured by the fuel pressure sensor 26.

  The exhaust gas after combustion is discharged to the exhaust pipe 11 via the exhaust valve 4. The exhaust pipe 11 is provided with a three-way catalyst 12 for purifying exhaust gas.

  The exhaust pipe 11 and the collector 15 are connected by an EGR passage 18. An EGR valve 14 is provided in the middle of the EGR passage 18. The opening degree of the EGR valve 14 is controlled by the ECU 9, and the exhaust gas in the exhaust pipe 11 is recirculated to the intake pipe 10 as necessary.

The ECU (engine control unit) 9 is an electronic control type including a microcomputer, and includes a fuel injection control device 27. The crank angle signal of the crank angle sensor 16 of the engine 1, the air amount signal of the AFM 20, the exhaust gas The oxygen concentration signal of the oxygen sensor 13 that detects the oxygen concentration in the gas, the accelerator opening signal of the accelerator opening sensor 22, and the fuel pressure signal of the fuel pressure sensor 26 are input, and the required torque to the engine is calculated from the accelerator opening. At the same time, the idle state is determined, the amount of intake air required for the engine 1 is calculated, and an opening signal corresponding to the intake air amount is output to the throttle valve 19.
The ECU 9 has a rotation speed detection unit that calculates the engine rotation speed from the crank angle signal of the crank angle sensor 16.

  The fuel injection control device 27 calculates a fuel amount corresponding to the intake air amount, outputs a current for the fuel injection valve 5 to perform fuel injection, and outputs an ignition signal to the spark plug 6.

  Next, the configuration of the fuel injection control device 27 according to the present embodiment will be described with reference to FIG. The fuel injection control device 27 is generally built in the ECU 9 shown in FIG.

  The CPU 57 of the fuel injection control device 27 calculates an appropriate energization time and injection start timing according to the operating state of the engine 1, and transmits a drive pulse Ti corresponding to the energization time to the injector drive IC 56 through the drive pulse transmission line 55. To do. The injector drive IC 56 that has received the drive pulse Ti switches on / off of the high-pressure side switching element 50, the low-pressure side switching element 51, and the ground-side switching element 52 to switch the electromagnetic coil of the fuel injection valve 5 (electromagnetic solenoid for valve opening drive). An exciting current is supplied to 53.

  The high voltage side switching element 50 is connected between the high voltage power supply VH and the high voltage side terminal of the electromagnetic coil 53. The high voltage power supply VH is 60 V, for example, and is generated by boosting the battery voltage by a DC / DC converter or the like.

  The low voltage side switching element 51 is connected between the low voltage power supply VB and the high voltage side terminal of the electromagnetic coil 53. The low voltage power supply VB is, for example, 12V corresponding to the battery voltage.

  The ground side switching element 52 is connected between the low voltage side terminal of the electromagnetic coil 53 and the ground potential.

  The injector drive IC 56 detects the current value flowing through the electromagnetic coil 53 by the current detection resistor element 60, and holds the target current value by switching the switching elements 50, 51, 52 on and off. Thus, the electromagnetic coil 53 can be energized.

  The diodes 58 and 59 are provided for discharging the current flowing through the electromagnetic coil 53. When both the low voltage side switching element 51 and the ground side switching element 52 are off, the diodes 58 and 59 are rapidly discharged.

  The injector driving IC 56 transmits and receives data through the CPU 57 and the communication line 54. The injector driving IC 56 has a function of changing the waveform of the current supplied to the electromagnetic coil 53 and the magnitude of the current value according to the data of the communication line 54. Therefore, the CPU 57 can change the current value supplied to the electromagnetic coil 53 and change the current waveform in accordance with the operating state of the internal combustion engine.

  Next, the relationship between the exciting current flowing through the electromagnetic coil 53 of the fuel injection valve 5 and the opening / closing valve of the valve body of the fuel injection valve 5 will be described with reference to the timing chart of FIG. FIG. 3 shows basic characteristics when the energization time to the electromagnetic coil 53 of the fuel injection valve 5 is normal. Among these, FIG. 3A shows a drive pulse Ti sent from the CPU 57 to the injector drive IC 56. 3B shows the exciting current Iex flowing through the electromagnetic coil 53, and FIG. 3C shows the valve body position Pv when the fuel injection valve 5 is driven. In FIG. 3C, opn indicates the valve opening position of the fuel injection valve 5, and cls indicates the valve closing position of the fuel injection valve 5.

  At the time t0, when the fuel injection start timing calculated by the CPU 57 is reached, the drive pulse Ti is transmitted to the injector drive IC 56 as shown in FIG. The injector drive IC 56 simultaneously turns on the high-pressure side switching element 50 and the ground-side switching element 52 of the fuel injection control device 27 shown in FIG. 2 when the drive pulse Ti signal rises, as shown in FIG. 3 (B). As shown in the figure, the valve opening current required for the quick opening of the electromagnetic coil 53 is supplied. A high voltage is applied to the electromagnetic coil 53 from the high voltage power supply VH, and a valve opening current is supplied.

  As shown in FIG. 3B, when the current value of the excitation current Iex reaches the peak current value Ipeak after the elapse of time tp from time t0, the injector drive IC 56 turns off the high-voltage side switching element 50. . The peak current value Ipeak is 11 A, for example. At this time, the electric charge given to the electromagnetic coil 53 circulates through the diode 59 and the electromagnetic coil 53 and is dissipated as heat. The time tp is an arrival time from the rise of the drive pulse Ti to the peak current value Ipeak which is the valve opening current value.

  At time t1, when the current value of the excitation current Iex approaches the second holding target value Ihold2 that can maintain the valve opening of the electromagnetic coil 53, the injector drive IC 56 turns on the low-voltage side switching element 51 and the ground-side switching element 52. Then, the electromagnetic coil 53 is energized from the low voltage power supply LH. The low pressure side switching element 51 is turned on / off so that the current value is maintained at the second holding target value Ihold2 that can maintain the valve opening. For example, the second holding target value Ihold2 is 3A.

  When the drive pulse Ti falls at time t2, the current supply to the electromagnetic coil 53 is stopped at the same time.

  The opening and closing of the fuel injection valve 5 (time points t01, t21) is caused by a delay in response of current caused by the internal circuit of the fuel injection control device 27 and the harness up to the fuel injection valve 5, the generated magnetic force and the response delay of the valve body. The fuel injection control device 27 is delayed from the time points t0 and t2 at which it is desired to open and close the valve. As shown in FIG. 3C, when the valve is opened, the valve body of the fuel injection valve 5 is completely moved to the valve opening position opn after the response delay time Tdop, and when the valve is closed, the response delay time Tdcl is closed. Later, the valve body of the fuel injection valve 5 is completely moved to the valve closing position cls.

  The energization control of the electromagnetic coil 53 by the fuel injection control device of the present embodiment will be described with reference to the timing chart shown in FIG. 4A shows the excitation current Iex flowing through the electromagnetic coil 53, FIG. 4B shows the drive pulse Ti sent from the CPU 57 to the injector drive IC 56, and FIG. 4C shows the on / off state of the high-voltage side switching element 50. 4D shows the on / off state of the low-voltage side switching element 51, and FIG. 4E shows the on / off state of the ground-side switching element 52.

  At time t0, as shown in FIG. 4B, between time tb and time t0 before the drive pulse Ti becomes high level, as shown in FIG. When the coil 53 is energized for a certain period of time with the precharge current value Ipre, the injector drive IC 56, as shown in FIGS. 4D and 4E, during the precharge current energization period (tb to t0). The low voltage side switching element 51 and the ground side switching element 52 are turned on.

  Thereby, a voltage is applied to the electromagnetic coil 53 from the low voltage power supply LH, and the low voltage side switching element 51 is repeatedly turned on and off, that is, a target precharge current is obtained by pulse control (duty ratio control). Energization is performed while maintaining the value Ipre. The precharge current value Ipre is a current value that does not open the fuel injection valve 5 and a current value within a time range, and may be about 1.5 A, for example.

  As described above, the energization is performed with the precharge current value Ipre prior to the rise of the drive pulse Ti, whereby the arrival time tp from the rise of the drive pulse Ti to the peak current value Ipeak can be reduced. Thereby, the valve opening delay of the electromagnetic coil 53 can be reduced.

  At time t0, when the fuel injection start timing calculated by the CPU 57 is reached, a drive pulse Ti is transmitted to the injector drive IC 56 as shown in FIG. As shown in FIGS. 4C and 4E, the injector drive IC 56 turns on the high-voltage side switching element 50 and the ground switching element 52 at the same time as shown in FIGS. The valve opening current required for the rapid valve opening is supplied. A high voltage is applied to the electromagnetic coil 53 from the high voltage power supply VH, and a valve opening current is supplied as shown in FIG.

  At time t1, when the current value of the exciting current Iex reaches the peak current value Ipeak (for example, 11A) as shown in FIG. 4 (A), the injector drive IC 56 is shown in FIG. 4 (C). As shown, the high-voltage side switching element 50 and the ground switching element 52 are turned off. Thereby, the electric charge of the electromagnetic coil 53 circulates through the diode 59 and the electromagnetic coil 53 and is dissipated as heat energy. At this time, as shown in FIG. 4E, the ground-side switching element 52 is also turned off at the same time, whereby the electric charge of the electromagnetic coil 53 is regenerated to the high voltage power source VH via the diode 58. , Decline rapidly.

  At time t2, as shown in FIG. 4A, the first holding target value (first holding current value) at which the current value of the exciting current Iex cannot keep the fuel injector 5 open. ) When approaching Ihold1, the injector driving IC 56 turns on the low-voltage side switching element 51 and the ground-side switching element 52 as shown in FIGS. 4D and 4E, and the electromagnetic coil from the low-voltage power supply LH. 53 is energized. At this time, the current value of the exciting current Iex is set to a first holding target value Ihold1, for example, about 1 A, at which the opening of the fuel injection valve 5 cannot be maintained by the duty ratio control of the low-pressure side switching element 51. The time for maintaining the first hold target value Ihold1 is set to a preset time th1.

  The set time th1 is about 0.2 ms. The first hold target value Ihold1 and the set time th1 may be variably set to appropriate values according to the operating state of the internal combustion engine, for example, the engine speed.

  The first holding target value Ihold1 may be changed according to the fuel pressure. In this case, the first current value Ihold1 is increased as the fuel pressure increases, and the first current value Ihold1 is decreased as the fuel pressure decreases.

  The first hold target value Ihold1 and the set time th1 may be changed according to the alcohol concentration of the fuel and the fuel temperature. An upper limit is set for the set time th1. This is to prevent the valve from closing if the first holding target value Ihold1 is held for an excessively long time.

  At the time t3 when the set time th1 has elapsed, the current value of the excitation current Iex is changed to a second holding target value (second holding current value) Ihold2 at which the fuel injection valve 5 can be kept open. The second holding target value Ihold is, for example, about 3 A, and the second holding target value Ihold is set by the duty ratio control of the low-voltage side switching element 51.

  After the time t2, if the current value of the excitation current Iex is kept at the first holding current value Ihold1, the fuel injection valve 5 cannot be kept open and closes. Therefore, after a predetermined time th1 has elapsed from the time t2. Changes the current value of the excitation current Iex to the second holding target value Ihold2 at which the fuel injection valve 5 can keep the valve open.

  The first holding current value Ihold1 is sufficiently smaller than the second holding current value Ihold2 that is necessary and sufficient to maintain the fuel injection valve 5 open, and the first holding current value Ihold1 is continuously energized with the first holding current value Ihold1. Is a current value at which the fuel injection valve 5 is closed. The difference between the absolute values of the first holding current value Ihold1 and the second holding current value Ihold2 is made sufficiently larger than the fluctuation of the current value observed when holding the current (for example, the fluctuation width w shown in FIG. 4). ing.

  At time t4, with the end of the fuel injection pulse calculated by the CPU 57, the drive pulse Ti becomes low level as shown in FIG. 4B, and the high voltage side switching element 50, the low voltage side switching element 51, All of the ground side switching elements 52 are turned off, and energization of the electromagnetic coil 53 is terminated.

  In the illustrated example, the pulse width Ti of the drive pulse is, for example, about 1.0 ms. Time t2 is about 0.4 ms after time t0, and time t3 is about 0.6 ms from time t0.

  Next, improvement of the excitation current flowing through the electromagnetic coil 53 of the fuel injection valve 5 and the valve closing delay of the fuel injection valve 5 will be described with reference to FIG. FIG. 5 shows the relationship between the excitation current flowing through the fuel injection valve 5 and the on / off valve of the (valve element) of the fuel injection valve 5 when the pulse width of the drive pulse Ti of the fuel injection valve 5 is small. This assumes, for example, a case where the drive pulse Ti becomes a low level at time tx as shown by a broken line in FIG.

  5A shows the drive pulse Ti, FIG. 5B shows the current value of the excitation current Iex, and FIG. 5C shows the valve body position Pvx when the normal fuel injection valve 5 is driven. FIG. 5D shows the valve body position Pv when the fuel injection valve 5 according to this embodiment is driven. 5C and 5D, opn indicates the valve opening position of the fuel injection valve 5, and cls indicates the valve closing position of the fuel injection valve 5.

  In FIG. 5B, the broken line a indicates that the high-voltage side switching element 50 and the ground-side switching element 52 are turned off simultaneously after energization with the peak current value Ipeak, which is the valve opening current, similarly to the excitation current shown in FIG. Thus, it is a normal current waveform that is rapidly discharged and holds the current value Iex at the second holding current value Ihold2. In this case, after energization with the peak current value Ipeak, there is a delay until the current disappears from the second holding current value Ihold2 to 0, so that the valve closing delay Tdcl is set as shown in FIG. There was a limit to making it smaller.

  On the other hand, as shown by a solid line c in FIG. 5B, after the current value of the electroexcitation current Iex reaches the peak current value Ipeak, the current value is the first that cannot hold the valve opening. When the first holding current value Ihold1 is reached, the energization of the fuel injection valve 5 is stopped at the time when the holding current value Ihold1 is reduced to the vicinity of the holding current value Ihold1, so that the delay until the current disappears to 0 is greatly reduced. Can be small.

  As a result, as shown in FIG. 5D, the valve closing delay Tdclc when the pulse width of the drive pulse Ti is small can be made smaller than usual.

  As described above, by maintaining the first holding current Ihold1 that is smaller than the second holding current value Ihold2 and cannot be kept open before being held at the second holding current value Ihold2, the electromagnetic coil 53 The internal current can be reduced once. Therefore, when energization to the electromagnetic coil 53 is terminated at time tx in FIG. 4, the electromagnetic coil 53 is quickly closed, and the valve closing delay can be reduced even when the pulse width of the drive pulse Ti is short.

  Next, improvement of the response delay of the fuel injection valve 5 due to the excitation current flowing through the electromagnetic coil 53 of the fuel injection valve 5 and the increase in the fuel pressure will be described with reference to FIG.

  6A shows the driving pulse Ti, FIG. 6B shows the exciting current Iex, FIG. 6C shows the valve element position Pvxx when the normal fuel injection valve 5 is driven, and FIG. D) each shows the valve body position Pv at the time of the drive of the fuel injection valve 5 by this embodiment. 6C and 6D, opn indicates the valve opening position of the fuel injection valve 5, and cls indicates the valve closing position of the fuel injection valve 5.

  In FIG. 6B, a dotted line a is an excitation current when the internal combustion engine is in a normal operation region, similarly to the excitation current shown in FIG. When the fuel pressure is high, the driving force required to close the fuel injection valve 5 at the time of valve opening is large, so that the valve opening delay Tdopaa becomes larger than usual as shown in FIG. On the other hand, as shown by the solid line b in FIG. 6B, when energization is performed with the precharge current Ipre value and the peak current value is increased to a current value Ipeaka higher than the normal current value Ipeaka, Coupled with energization by the precharge current value Ipre, the rise of the current flowing through the electromagnetic coil 53 of the fuel injection valve 5 is accelerated, the magnetic force generated by the increase of the peak current value increases, and the valve opening force of the valve body increases. Therefore, the valve opening delay can be reduced as shown by Tdopb in FIG.

  Further, by increasing the second holding current from Ihold2aa to Ihold2b, it is possible to prevent the fuel injection valve 5 from being unintentionally closed even when the fuel pressure is high. However, in this case, since the current value when the current supply to the electromagnetic coil 53 is cut off increases, the valve closing delay increases as indicated by Tdclb shown by the solid line in FIG.

  On the other hand, in FIG. 6B, when the current supplied to the electromagnetic coil 53 is interrupted, the counter electromotive current Irev indicated by the alternate long and short dash line d is caused to flow through the electromagnetic coil 53, thereby flowing into the electromagnetic coil 53. Thus, the exciting current can be quickly eliminated, and the speed at which the valve body returns to the valve closing position can be increased. Thereby, the valve closing delay of the fuel injection valve 5 can be shortened to Tdcld in FIG.

  As described above with reference to FIGS. 5 and 6, valve opening delay and valve closing delay can be shortened by changing the waveform and current value of the excitation current Iex for driving the fuel injection valve 5. When in the operation region where it is desired to reduce the valve closing delay and to inject the minimum injection amount, or in the high load operation region where it is desired to increase the fuel pressure, the fuel injection valve 5 is changed by changing from the normal current waveform. The on-off valve characteristics of the fuel can be improved, and a desired amount of fuel can be injected with high accuracy.

  Next, the fuel injection characteristics when the fuel injection control device 27 according to this embodiment is driven by changing the waveform of the current supplied to the electromagnetic coil 53 of the fuel injection valve 5 will be described with reference to FIG. FIG. 7 is a graph schematically showing the relationship between the energization time for the electromagnetic coil 53 of the fuel injection valve 5 and the fuel injection amount.

  A line e in FIG. 7 shows the injection amount characteristic in a standard current waveform. For example, the injection amount characteristic when the current waveform is changed to a waveform as shown in FIG. The line f overlaps the line e when the energization time is 1.0 ms, as shown in FIG. 4A. The current value is such that the fuel injection valve 5 cannot keep the valve open (first holding current value). This is because the time when Ihold1) flows is from the energization pulse start time t0 to the time t3 after 1.0 ms.

  While the energization time is in the range of 0.4 to 1.0 ms, the current value at the end of energization is the first holding current value Ihold1, so that the current waveform shown by the solid line c in FIG. Becomes smaller as shown in FIG. Therefore, even when the energization time is the same as that of the standard current waveform, the injection amount decreases, and the injection amount characteristic shown by the line f in FIG. 7 is obtained. Since the current value at the end of energization becomes the second holding current value Ihold2 in FIG. 4 (A) after the energization time is 1.0 ms, the valve closing delay is usually as shown in FIG. 3 (C). The injection amount characteristic is the same as that of the line e.

  Next, when the current waveform is changed to, for example, a waveform as shown by a line b in FIG. 6B, the injection amount characteristic is as shown by a line g in FIG. By conducting energization with the precharge current value Ipre and then increasing the peak current to Ipeakb, the valve opening delay was reduced, so that fuel can be injected before the energization time of 0.4 ms.

  Further, in the waveform shown by the line b in FIG. 6B, the second holding current value Ihold2b is larger than the normal holding current, and therefore the valve closing delay Tdclb is large as shown in FIG. 6D. Become. As a result, even when the energization time is the same as that of the standard current waveform, the injection amount increases, and the injection amount characteristic indicated by the line g in FIG. 7 is obtained.

  When the current waveform supplied to the electromagnetic coil 53 of the fuel injection valve 5 is changed from the injection amount characteristic shown in FIG. 7, the injection amount characteristic also changes to lines e, f, and g. At this time, even in the same energization time ts, the injection amounts have different values.

  FIG. 8 shows one embodiment of the fuel injection control device 27 according to the present invention. The fuel injection control device 27 of the present embodiment includes a basic injection time calculation unit 101, a nonlinearity correction calculation unit 102, and a valve response delay calculation unit 103.

  The basic injection time calculation unit 101 calculates the amount of intake air taken in by the internal combustion engine, the target equivalence ratio for setting a certain target value to the mixing ratio (air-fuel ratio) of the intake air amount and the fuel amount, and the residual oxygen concentration in the exhaust gas. An air-fuel ratio correction for correcting the air-fuel ratio to a target equivalent ratio, a deviation of the air-fuel ratio when there is no air-fuel ratio correction is stored for each operation region of the engine 1, and a fuel injection amount is previously stored as a learning amount. The basic injection time is calculated by performing calculations such as air-fuel ratio correction to be corrected and fuel pressure correction for correcting the fuel injection time based on the fuel pressure detected by the fuel pressure sensor provided in the high-pressure fuel pipe.

  After calculating the basic injection time, the non-linearity correction calculation unit 102 performs non-linearity correction for correcting non-linearity between the basic injection time and the fuel flow rate caused by the characteristics of the fuel injection valve 5, and calculates the energization time Te. .

  As described with reference to FIG. 3, there is a response delay in opening and closing the fuel injection valve 5, and the response delay mainly depends on the fuel pressure. In response to this, the valve response delay calculation unit 103 calculates the valve response delay time (correction time) TSd according to the fuel pressure, and the addition unit 104 calculates the sum of the energization time Te, thereby fuel injection. The final energization time Ti to the valve 5 can be calculated.

  For example, the current waveform shown in FIG. 3B is a normal current waveform, and the electromagnetic coil 53 of the fuel injection valve 5 is matched with the operating state of the engine 1 as shown in FIGS. 4A and 6B. When the setting of the current waveform and the current value of the current to be supplied to is changed, as described with reference to FIG. 7, even when the same energization time Ti is set, the injected fuel amount becomes a different value. Therefore, simply by the correction by the valve response delay time TSd according to the fuel pressure, the fuel injection amount after changing the setting of the current waveform and the current value does not coincide with the fuel injection amount in the case of the normal current waveform. As a result, a deviation from the target equivalent ratio occurs, which may hinder the performance improvement of the engine 1.

  Next, one embodiment of the fuel injection control device 27 corresponding to a case where the setting of the current waveform and the current value of the current flowing through the electromagnetic coil 53 of the fuel injection valve 5 is changed will be described with reference to FIG. .

  The fuel injection control device 27 of the present embodiment changes the setting of the current waveform and the current value of the current flowing through the electromagnetic coil 53 of the fuel injection valve 5 as described with reference to FIGS. Has a current waveform / current value calculation unit 105 that instructs the injector drive IC 56.

  The valve response delay time calculation unit 103 includes a plurality of calculation units that calculate the valve response delay time TSd according to the fuel pressure, as indicated by reference numerals 103a to 103n. The calculation units 103a to 103n each calculate the valve response delay time TSd corresponding to the fuel pressure with individual characteristics.

Following the valve response delay time calculation unit 103, one of the valve response delay times TSd calculated by the calculation units 103a to 103n of the valve response delay time calculation unit 103 is current waveform / current set value changing means. A selector unit 106 is provided for selection based on a command output from the current waveform / current value calculation unit 105.
The selector unit 106 may be realized by a software process of a computer.

  When the engine 1 is in the normal operation region, the fuel injection control device 27 energizes the electromagnetic coil 53 of the fuel injection valve 5 with the current waveform shown in FIG. The valve response delay time TSd corresponding to the current waveform in this case is selected, for example, by the calculation unit 103a by the action of the selector unit 106 based on the command from the current waveform / current value calculation unit 105. Thus, the valve response delay time calculation unit 103 and the selector unit 106 constitute a valve response delay time calculation unit.

  When the fuel injection control device 27 is energizing the electromagnetic coil 53 of the fuel injection valve 5 with the current waveform shown in FIG. 4A, for example, what is calculated in the calculation unit 103b by the same selection action. Selected. Further, when the fuel injection control device 27 is energizing the electromagnetic coil 53 of the fuel injection valve 5 with the current waveform shown in FIG. 6B, for example, the calculation unit 103n performs the calculation by the same selection action. Is selected.

  In the present embodiment, the calculation of the valve response delay time with respect to three patterns of current waveform changes has been described. However, the current waveform change pattern is not limited to three, and more patterns can be handled. Is also possible.

  As a specific example, the valve response delay time calculation unit 103 and the selector unit 106 use the current waveform, the current value setting change, and the fuel injection valve 5 to increase the magnetic force generated at the initial stage of opening of the fuel injection valve 5 more than usual. The current waveform for supplying a current that does not open the fuel injection valve 5 before the drive timing, the current value setting change, or the current that increases the current supplied to the fuel injection valve 5 from the high-voltage power supply VH than usual. When the setting of the waveform and current value is changed, the valve response delay time TSd is made shorter than usual.

  Further, the current waveform for reducing the magnetic force generated immediately before the fuel injection valve 5 closes, the current value setting change, and the current supplied to the fuel injection valve 5 from the low voltage power source VB are reduced more than usual. Changing the current waveform and current value settings, or changing the current waveform and current value settings for supplying current in the opposite direction to the current before shutting off when the current supplied to the fuel injection valve 5 from the low-voltage power supply VB is shut off When the operation is performed, the valve response delay time TSd is made longer than usual.

Next, the fuel injection control flow by the fuel injection control device 27 of the present embodiment will be described with reference to the flowchart of FIG.
During the operation of the engine 1, the ECU 9 determines in which operating region the engine 1 is located (step S100). As an index for determination, for example, the number of revolutions of the engine 1 and the amount of intake air can be considered.

  Next, the ECU 9 determines whether or not it is necessary to change the setting of the current waveform and the current value of the current supplied to the electromagnetic coil 53 of the fuel injection valve 5 based on the operation region determination of the engine 1 (step S110). ). When it is determined that it is not necessary to change the setting of the current waveform and current value, a normal valve response delay time calculation result is selected (step S120).

  On the other hand, when it is determined that the change is necessary, the CPU 57 instructs the fuel injector injector drive IC 56 to change the current waveform and current value via the communication line 54 (step S130).

  The injector drive IC 56 can energize the electromagnetic coil 53 of the fuel injection valve 5 with a current waveform as shown in FIGS. 3B, 4A, and 6B, for example, in accordance with an instruction from the ECU 9. Change the setting to. Then, the CPU 57 selects the valve response delay time calculated by the calculation units 103a to 103n of the valve response delay time calculation unit 103, corresponding to the changed current waveform (step S140).

  Next, the basic injection time calculated by another calculation sequence is added to the valve response delay time calculated in step S120 or step S140 (step S160). The energization time for energizing the electromagnetic coil 53 is determined (step S170).

  Next, in the fuel injection control device 27 according to the present embodiment, the excitation current flowing in the electromagnetic coil 53 of the fuel injection valve 5 when the high voltage power supply VH fails will be described with reference to FIG.

  The normal current waveform is a current waveform indicated by a dotted line N in FIG. When the high voltage power supply VH fails, it becomes impossible to supply the excitation current Iex having the peak current value Ipeak shown in FIG. Therefore, in this case, the exciting current Iex with the second holding current value Ihold2 is supplied from the low voltage power supply LV, and the fuel injection valve 5 is opened and held.

  At this time, since the exciting current Iex having the peak current value Ipeak is not supplied, the magnetic force at the initial opening of the fuel injection valve 5 is small, and the valve opening delay TdopF is larger than the normal valve opening delay TdopN. For this reason, at the time of a high voltage failure, the fuel injection amount similar to the normal time can be realized by increasing the energization time to the electromagnetic coil 53 of the fuel injection valve 5 by the increase in the valve opening delay.

  As described with reference to FIGS. 9 and 10, when the current waveform is changed so that the current is supplied from only the low voltage power source to the electromagnetic coil 53 of the fuel injection valve 5 when the high voltage power source fails, the selector After the valve response delay time calculation result is switched by the unit 106, the final energization time can be calculated by adding to the basic injection time.

  As described above, the correction amount for correcting the delay in opening and closing is changed in accordance with the change in setting of the current waveform and current value, and the energization time to the electromagnetic coil 53 of the fuel injection valve 5 is changed. With such a configuration, the accuracy of the fuel injection amount can be maintained and improved even when the current waveform or current value supplied to the electromagnetic coil 53 of the fuel injection valve 5 is changed.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to the above-mentioned embodiment. Moreover, each component is not limited to the said structure, unless the characteristic function of this invention is impaired.

1 Internal combustion engine
5 Fuel injection valve 9 ECU (Engine Control Unit)
27 Fuel Injection Control Device 50 High Pressure Side Switching Element 51 Low Pressure Side Switching Element 52 Ground Side Switching Element 53 Electromagnetic Coil 56 Injector Drive IC
57 CPU
101 Basic Injection Time Calculation Unit 102 Nonlinear Correction Calculation Unit 103 Valve Response Delay Time Calculation Units 103a to 103n Calculation Unit 105 Current Waveform / Current Set Value Change Calculation Unit 106 Selector Unit VH High Voltage Power Supply VB Low Voltage Power Supply

Claims (6)

The fuel injection amount supplied to the internal combustion engine is converted into the valve opening time of the electromagnetic fuel injection valve, the opening and closing delays of the fuel injection valve are calculated as correction times, and the valve opening time is calculated by the correction time. A fuel injection control device for an internal combustion engine that corrects and controls the energization time of the fuel injection valve to control the fuel injection amount,
The fuel injection control device includes: a current waveform / current set value changing means capable of changing a setting of at least one of a current waveform or a current value of a current supplied to the fuel injection valve; and the current waveform / current set value change. A valve response delay time calculating means for variably setting the correction time for correcting the opening and closing delays of the fuel injection valve in accordance with a change in setting of the current waveform and current value by the means, and a high voltage power supply Supplying a current to the fuel injector and opening the fuel injector by a magnetic force generated by the current, and then supplying a current from a low voltage power source to the fuel injector instead of the high voltage power source, Conduct energization control to keep the fuel injection valve open,
The current waveform / current set value changing means performs a setting change of a current waveform and a current value for reducing the magnetic force generated immediately before the fuel injection valve is closed than usual,
The fuel injection control device for an internal combustion engine, wherein the valve response delay time calculating means makes the correction time longer than usual in accordance with a change in setting of the current waveform and current value. The fuel injection amount supplied to the internal combustion engine is converted into the valve opening time of the electromagnetic fuel injection valve, the opening and closing delays of the fuel injection valve are calculated as correction times, and the valve opening time is calculated by the correction time. A fuel injection control device for an internal combustion engine that corrects and controls the energization time of the fuel injection valve to control the fuel injection amount,
The fuel injection control device includes: a current waveform / current set value changing means capable of changing a setting of at least one of a current waveform or a current value of a current supplied to the fuel injection valve; and the current waveform / current set value change. A valve response delay time calculating means for variably setting the correction time for correcting the opening and closing delays of the fuel injection valve in accordance with a change in setting of the current waveform and current value by the means, and a high voltage power supply Supplying a current to the fuel injector and opening the fuel injector by a magnetic force generated by the current, and then supplying a current from a low voltage power source to the fuel injector instead of the high voltage power source, Conduct energization control to keep the fuel injection valve open,
The current waveform / current set value changing means sets the current waveform and current value for supplying current in the opposite direction to the current before cutoff when the current supplied to the fuel injection valve from the low voltage power source is cut off. Make changes,
The fuel injection control device for an internal combustion engine, wherein the valve response delay time calculating means makes the correction time longer than usual in accordance with a change in setting of the current waveform and current value. The current waveform / current setting value changing means performs a setting change of a current waveform and a current value for supplying a current that does not open the fuel injection valve before the drive timing of the fuel injection valve,
2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the valve response delay time calculation means shortens the correction time in accordance with the setting change of the current waveform and the current value. The current waveform / current setting value changing means performs a setting change of a current waveform and a current value that increase a current supplied from the high-voltage power source to the fuel injection valve more than usual.
2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the valve response delay time calculation means shortens the correction time in accordance with the setting change of the current waveform and the current value. The current waveform / current set value changing means performs a setting change of a current waveform and a current value for reducing current supplied from the low voltage power source to the fuel injection valve more than usual.
2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the valve response delay time calculation unit makes the correction time longer than usual in accordance with a change in setting of the current waveform and the current value. Determining whether the high-voltage power supply is normal;
The current waveform / current set value changing means stops the current supply from the high voltage power supply when it is determined that the high voltage power supply is not normal, and supplies the current to the fuel injection valve only from the low voltage power supply. Change the waveform and current settings,
2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the valve response delay time calculation unit makes the correction time longer than usual in accordance with a change in setting of the current waveform and the current value.