JP3680505B2 - Fuel injection control device for direct-injection spark-ignition internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a fuel injection control device for a direct injection spark ignition type internal combustion engine.
[0002]
[Prior art]
  In recent years, a direct-injection spark-ignition internal combustion engine has attracted attention. In this engine, the fuel is injected into the combustion chamber by switching the combustion method according to the operating conditions of the engine, that is, by injecting fuel in the intake stroke. Is controlled to switch between homogeneous combustion, which is performed by diffusing the gas to form a homogeneous mixture, and stratified combustion, in which fuel is injected in the compression stroke to form a stratified mixture intensively around the spark plug Is generally used (see JP 59-37236 A).
[0003]
[Problems to be solved by the invention]
  By the way, in the fuel injection control device of the internal combustion engine, the cylinder intake air amount is calculated every predetermined time, and the fuel injection amount is calculated based on this to obtain the target air-fuel ratio. The quantity is set as the fuel injection control output.
  However, in direct-injection spark ignition internal combustion engines, when performing fuel injection after the intake valve closing timing during stratified combustion, the fuel injection amount is calculated based on the cylinder intake air amount calculated in the vicinity of the injection timing. If set, the actual cylinder intake air amount is determined at the intake valve closing timing, so the fuel injection amount does not match the actual cylinder intake air amount, and the air-fuel ratio cannot be correctly controlled to the target air-fuel ratio.
[0004]
  If the air-fuel ratio cannot be correctly controlled to the target air-fuel ratio in this way, the air-fuel ratio around the spark plug cannot be kept within an appropriate range during stratified combustion, which is likely to cause misfire and smoke, which is preferable in terms of operability and exhaust performance. No results.
  Therefore, it is considered that the cylinder intake air amount is calculated at the intake valve closing timing, and the fuel injection amount at the injection timing after the intake valve closing timing is set based on the cylinder intake air amount at the intake valve closing timing. (Japanese Patent Application No. 9-185143).
[0005]
  On the other hand, torque correction for preventing rotational fluctuation is generally performed by ignition timing control. However, in stratified combustion in which fuel injection is performed after the intake valve closing timing, the sensitivity of the ignition timing is sharp (combustion establishment). Since the range is narrow) and cannot be corrected, it is considered to correct the fuel injection amount, particularly the target air-fuel ratio, to perform torque correction. In this case, the rotation is synchronized, that is, the crank angle is 720 ° / number of cylinders. Since the engine speed is calculated every time the reference crank angle signal is input, it is necessary to perform torque correction with a rotation synchronization job (job executed in synchronization with generation of the reference crank angle signal REF; REF job). .
  In particular, during sudden deceleration with a large rotation reduction rate, it is conceivable that an engine stall may occur if torque correction cannot be performed reliably.
[0006]
  Therefore, by adjusting the generation timing of the reference crank angle signal to the intake valve closing timing, the fuel that includes torque correction in the rotation synchronization job in synchronization with the generation of the signal representative of the intake valve closing timing, that is, the generation of the reference crank angle signal. It was considered to calculate the injection amount.
  However, since the fuel injection amount is used as a parameter for calculating the fuel injection timing and the ignition timing, the fuel injection amount is calculated by a time synchronous job (job executed every predetermined time; scheduled job) for these purposes. There is also a need.
[0007]
  Then, it becomes necessary to calculate the fuel injection amount for both the rotation synchronization job and the time synchronization job. In particular, the calculation load of the fuel injection amount in the rotation synchronization job increases the calculation load. It has been.
  In view of such a situation, the present inventionNot only can the fuel injection amount control be performed on the basis of the cylinder intake air amount at the intake valve closing timing, but also torque correction synchronized with the rotation can be incorporated with good response to the fuel injection amount control. Can be reducedDirect-injection spark ignition internal combustion engineofAn object is to provide a fuel injection control device.
[0008]
[Means for Solving the Problems]
  Therefore, in the invention according to claim 1, in a direct injection spark ignition internal combustion engine that includes a fuel injection valve that directly injects fuel into the combustion chamber and injects fuel after the intake valve closing timing, as shown in FIG. In addition,Intake valve closing timing signal generating means for generating a signal representative of the intake valve closing timing, and when the intake valve is closed In synchronism with the generation of a signal representative of the period, torque correction amount calculating means for calculating a torque correction amount based on a torque correction request for calculating the fuel injection amount, and basic fuel injection based on the cylinder intake air amount every predetermined time A time-synchronized fuel injection amount calculation means for calculating the fuel injection amount by performing at least correction by the torque correction amount calculated by the torque correction amount calculation means on the amount;With respect to the basic fuel injection amount based on the cylinder intake air amount in synchronization with the generation of a signal representative of the intake valve closing timing at the time of detection of the sudden deceleration state and the sudden deceleration state detection means,at leastCalculated by the torque correction amount calculation meansWith correction by torque correction amount,Fuel for calculating fuel injection amount at sudden deceleration, and fuel injection amount calculated by the time-synchronized fuel injection amount calculating unit or the fuel injection amount calculating unit for sudden deceleration as fuel injection control output Injection control output setting means;The fuel injection control is performed with the fuel injection amount obtained by the calculation of the fuel injection amount by the time-synchronized fuel injection amount calculation means for the first time after the generation of the signal representative of the intake valve closing timing, except when the sudden deceleration state is detected. Updating of the fuel injection control output by the output setting means is permitted, and updating of the fuel injection control output is prohibited thereafter until the end of fuel injection, and when the sudden deceleration state is detected, the fuel by the sudden deceleration fuel injection amount calculating means is detected. An update permission that permits updating of the fuel injection control output by the fuel injection control output setting means with the fuel injection amount obtained by calculation of the injection amount and prohibits updating of the fuel injection control output thereafter until the end of fuel injection. Prohibited means,The fuel injection control device is configured in the direct injection spark ignition type internal combustion engine.
[0009]
  In other words, the fuel injection amount is calculated in a time-synchronized job, but after the signal representative of the intake valve closing timing is generated, the fuel injection control output is updated until the first time-synchronized job in which the latest value of the torque correction amount can be taken. Permits and updates are prohibited after that. In other words, after calculating the torque correction amount in synchronization with the generation of the signal representative of the intake valve closing timing in the rotation synchronization job, the fuel injection amount is calculated in the first time synchronization job, and this is used as the fuel injection control output. To do.
[0010]
  In this case, at the time of low rotation, the time synchronization job surely runs between the intake valve closing timing and the compression stroke injection timing, and the torque correction amount calculated in synchronization with the generation of the signal representative of the intake valve closing timing is Although it is certainly reflected in the actual fuel injection amount, there are cases where the time synchronization job does not enter on the high rotation side.
  At high speeds, the amount of change in the fuel injection amount between the signals is small, which is considered to be no problem. However, at sudden deceleration with a large reduction rate of rotation, if torque correction cannot be performed reliably, engine stall may occur. It is done.
[0011]
  there,At the time of sudden deceleration, the fuel injection amount is calculated immediately after calculating the torque correction amount in synchronism with the generation of the signal representative of the intake valve closing timing, that is, in rotation synchronization, thereby setting the fuel injection control output. . In other words, during sudden deceleration where the torque correction amount must be reliably reflected in the next combustion, the fuel injection amount is calculated (corrected) simultaneously with the calculation of the torque correction amount, thereby preventing the engine stall.
  Further, after calculating the fuel injection amount in rotation synchronization during sudden deceleration, the calculation load can be reduced by prohibiting subsequent updates of the fuel injection control output.
[0012]
  In the invention according to claim 2, the intake valve closing timing signal generating means is a reference crank angle signal generating means, and the generation timing of the reference crank angle signal generated every crank angle of 720 ° / number of cylinders in synchronism with engine rotation. In accordance with the intake valve closing timing, and the reference crank angle signal is used as a signal representative of the intake valve closing timing.
  In the invention according to claim 3, the torque correction amount calculating means compares the actual engine speed and the target engine speed, and corrects the torque to correct the air-fuel ratio in the direction of decreasing the engine speed deviation based on the comparison result. The correction amount is calculated.
[0013]
  In the invention according to claim 4, as the cylinder intake air amount calculation means, means for delaying the intake air amount detected based on a signal from an air flow meter arranged in the intake passage and calculating the cylinder intake air amount is provided. It is characterized by providing.
[0014]
【The invention's effect】
  According to the invention of claim 1,The fuel injection amount is calculated in a time-synchronized job, but after the signal representative of the intake valve closing timing is generated, the fuel injection control output can be updated until the first time-synchronized job where the latest value of the torque correction amount can be taken. Thereafter, since the update is prohibited, the fuel injection control can be performed using the fuel injection amount calculated almost based on the cylinder intake air amount at the intake valve closing timing. Therefore, the fuel injection amount corresponding to the cylinder intake air amount can be accurately given even in the transient state, and the control accuracy of the air-fuel ratio can be improved. As a result, the air-fuel ratio of the combustion chamber can be achieved as intended, and operability can be improved. Further, since the air-fuel ratio accuracy is good, exhaust components (HC, NOx, smoke, etc.) are not deteriorated.
[0015]
  Further, torque correction in rotation synchronization can be incorporated with good response to the fuel injection amount control.
  Further, although the calculation of the torque correction amount is performed by the rotation synchronization job, the calculation of the normal fuel injection amount may be performed only by the time synchronization job, so that the calculation load can be reduced.
  Further, at the time of sudden deceleration, the fuel injection amount is calculated immediately after calculating the torque correction amount in synchronism with the generation of the signal representative of the intake valve closing timing, that is, in rotation synchronization, and the fuel injection control output is thereby calculated. By setting, when it is necessary to reliably reflect the torque correction amount in the next combustion, such as during sudden deceleration, the calculation of the fuel injection amount that reflects the latest torque correction amount is guaranteed to ensure the engine stall. Can be prevented.
  Furthermore, after the fuel injection amount is calculated in rotation synchronization during sudden deceleration, the calculation load can be reduced by prohibiting subsequent updates of the fuel injection control output.
[0016]
  According to the second aspect of the invention, since the reference crank angle signal is used as a signal representative of the intake valve closing timing by adjusting the generation timing of the reference crank angle signal to the intake valve closing timing, a special sensor or the like is provided. And can be implemented.
  According to the third aspect of the present invention, the torque correction amount is set so that the actual engine speed and the target speed are compared with each other in rotation synchronization, and the air-fuel ratio is corrected in a direction to reduce the speed deviation based on the comparison result. Since this can be quickly reflected in the fuel injection amount control, fluctuations in rotation can be prevented by torque correction.
[0017]
  According to the fourth aspect of the invention, when calculating the cylinder intake air amount, the intake air amount detected based on the signal from the air flow meter disposed in the intake passage is subjected to a delay process to reduce the cylinder intake air amount. By calculating, the cylinder intake air amount can be accurately obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below.
  FIG. 2 is a system diagram of a direct injection spark ignition type internal combustion engine showing an embodiment. First, this will be described.
  Air is sucked into the combustion chamber of each cylinder of the internal combustion engine 1 mounted on the vehicle under the control of the electric throttle valve 4 from the air cleaner 2 through the intake passage 3.
[0019]
  The opening degree of the electronically controlled throttle valve 4 is controlled by a step motor or the like that is operated by a signal from the control unit 20.
  An electromagnetic fuel injection valve (injector) 5 is provided to inject fuel (gasoline) directly into the combustion chamber.
  The fuel injection valve 5 is energized to the solenoid by an injection pulse signal output in the intake stroke or the compression stroke in synchronization with the engine rotation from the control unit 20 to open the valve, and injects fuel adjusted to a predetermined pressure. It is like that. In the case of intake stroke injection, the injected fuel diffuses into the combustion chamber to form a homogeneous mixture, and in the case of compression stroke injection, a stratified mixture is formed intensively around the spark plug 6. Based on the ignition signal from the control unit 20, the ignition plug 6 ignites and burns (homogeneous combustion or stratified combustion). Combustion methods are classified into homogeneous stoichiometric combustion, homogeneous lean combustion, and stratified lean combustion in combination with air-fuel ratio control.
[0020]
  Exhaust gas from the engine 1 is discharged from an exhaust passage 7, and an exhaust purification catalyst 8 is interposed in the exhaust passage 7.
  The control unit 20 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, and signals are input from various sensors.
[0021]
  As the various sensors, crank angle sensors 21 and 22 for detecting rotation of the crankshaft or camshaft of the engine 1 are provided. These crank angle sensors 21, 22 serve as reference crank angle signal generating means at a predetermined crank angle position (predetermined crank angle position before compression top dead center of each cylinder) for each crank angle of 720 ° / number of cylinders. The reference crank angle signal REF is output and the unit crank angle signal POS is output every 1 to 2 °, and the engine speed Ne can be calculated from the cycle of the reference crank angle signal REF.
[0022]
  In particular, the crank angle position at which the reference crank angle signal REF is generated is near the intake valve closing timing of each cylinder, specifically, in the case of four cylinders, 130 ° before the compression top dead center of each cylinder (50 after the intake bottom dead center). The reference crank angle signal REF is selected as a signal representative of the intake valve closing timing. Therefore, the crank angle sensors 21 and 22 are intake valve closing timing signal generating means.
[0023]
  The crank angle sensor 22 that detects camshaft rotation outputs a cylinder discrimination signal PHASE corresponding to a specific cylinder at a predetermined crank angle position at every crank angle of 720 °, thereby enabling cylinder discrimination.
  Other sensors include an air flow meter 23 for detecting the intake air flow rate Qa upstream of the throttle valve 4 in the intake passage 3, an accelerator sensor 24 for detecting the accelerator opening (accelerator pedal depression amount) ACC, and opening of the throttle valve 4. A throttle sensor 25 for detecting the degree TVO (including an idle switch that is turned on when the throttle valve 4 is fully closed), a water temperature sensor 26 for detecting the cooling water temperature Tw of the engine 1, and a rich exhaust air / fuel ratio in the exhaust passage 7 O to output signals according to lean₂A sensor 27, a vehicle speed sensor 28 for detecting the vehicle speed VSP, and the like are provided.
[0024]
  Here, the control unit 20 performs a predetermined calculation process by a built-in microcomputer while inputting signals from the various sensors, so that the throttle opening by the electric throttle valve 4 and the fuel by the fuel injection valve 5 are processed. The injection amount, the injection timing, and the ignition timing by the spark plug 6 are controlled.
  For throttle control (control of the electric throttle valve 4), the motor of the electric throttle valve 4 is driven and opened according to the target torque tTRQ of the engine set from the accelerator opening ACC and the engine speed Ne. Control the degree.
[0025]
  As for fuel injection control (control of the fuel injection valve 5), a combustion method is set according to the engine operating conditions, and the fuel injection amount and injection timing by the fuel injection valve 5 are controlled accordingly.
  Specifically, a plurality of maps that determine the combustion method using the engine speed Ne and the basic fuel injection amount Tp as parameters are provided for each condition such as the water temperature Tw and the time after start-up. From the map selected from these conditions, The combustion mode is set to either homogeneous stoichiometric combustion, homogeneous lean combustion, or stratified lean combustion according to the actual engine operating condition parameters.
[0026]
  As a result of the determination of the combustion method, in the case of homogeneous stoichiometric combustion, the fuel injection amount is set to be equivalent to the stoichiometric air-fuel ratio (14.6), and O₂While performing the air-fuel ratio feedback control by the sensor 27, the injection timing IT is set to the intake stroke, and homogeneous stoichiometric combustion is performed. In the case of homogeneous lean combustion, the fuel injection amount is set to be equivalent to a lean air fuel ratio of 20 to 30 and open control is performed, while the injection timing IT is set to the intake stroke to perform homogeneous lean combustion. In the case of stratified lean combustion, the fuel injection amount is set to be equivalent to a lean air / fuel ratio of about 40, and open control is performed, while the injection timing IT is set to the compression stroke to perform stratified lean combustion. The injection timing IT is variably set with the engine speed Ne and the basic fuel injection amount Tp as parameters, according to a map for each combustion method.
[0027]
  The ignition control (control of the spark plug 6) is controlled by setting the ignition timing ADV by referring to a map using the engine speed Ne and the basic fuel injection amount Tp as parameters for each combustion method.
  Next, fuel injection control according to the present invention, that is, fuel injection control in the case of performing fuel injection after the intake valve closing timing (during the compression stroke) during stratified combustion will be described with reference to the flowcharts of FIGS. .
[0028]
  FIG. 3 shows a scheduled job for calculating the basic fuel injection amount, specifically a 4 ms job.
  In S1, the intake air flow rate Qa detected by the air flow meter 23 is read.
  In S2, the raw basic fuel injection amount (pulse width) RTp corresponding to the stoichiometric amount corresponding to the intake air amount per combustion is calculated by the following equation using the intake air flow rate Qa and the engine speed Ne.
[0029]
      RTp = K × Qa / Ne where K is a constant.
  In S3, the raw basic fuel injection amount RTp is delayed by the manifold filling delay by the following equation (weighted average equation), and the basic fuel injection amount (pulse width) Tp equivalent to the stoichiometric air amount corresponding to the cylinder intake air amount is obtained. Is calculated. This portion corresponds to cylinder intake air amount calculation means and basic fuel injection amount calculation means.
[0030]
      Tp = RTp × Fload + Tp_-1× (1-Fload)
  Where Fload is a weighted average rate constant, Tp_-1Is the previous value of Tp.
  FIG. 4 shows a REF job, which is executed in synchronization with the generation of the reference crank angle signal REF for each cylinder. Therefore, it is executed at the intake valve closing timing for each cylinder.
  In S11, the cylinder immediately after the REF flag FPPFSTn for each cylinder (n) is set to 1 for the cylinder identified.
[0031]
  The flag immediately after REF FAPPFSTn is set to 0 in S36 of a 10 ms job in FIG. Specifically, it is set to 1 by the generation of the reference crank angle signal REF, and is set to 0 by the second 10 ms job after the generation of the reference crank angle signal REF.
  In S12, the engine speed Ne is calculated based on the cycle of the reference crank angle signal REF.
[0032]
  In S13, it is determined whether or not there is a torque correction request.
  In S14, the engine speed Ne is compared with the target speed tNe. When Ne <tNe, the torque correction amount PIPER is increased by a minute amount (or an amount corresponding to the speed deviation) in S15. Conversely, when Ne> tNe, the torque correction amount PIPER is decreased by a minute amount (or an amount corresponding to the rotational speed deviation) in S16. The torque correction amount PIPER is for correcting the target equivalent ratio (= 14.6 / target air-fuel ratio) as will be described later, and the reference value is 1 (= 100%), and the engine speed When the torque is increased so as to increase the torque, the value is larger than 1. On the contrary, when the torque is decreased so as to decrease the engine speed, it is calculated smaller than 1. This portion corresponds to torque correction amount calculation means.
[0033]
  In S17, it is determined whether or not the vehicle is suddenly decelerating (that is, a request for torque correction during sudden deceleration). Whether or not the engine is suddenly decelerated is determined based on the amount of change in the engine speed Ne. This portion corresponds to the sudden deceleration state detecting means.
  If this determination is NO (normal time), the process ends without executing S41 to S44. The processing of S41 to S44 will be described later.
[0034]
  FIG. 5 shows an ignition job, which is executed for each cylinder at the ignition timing (after the passage of FADV = 130 ° −ADV from the reference crank angle signal REF of each cylinder).
  In S21, for each ignition cylinder (n), the cylinder-specific update prohibition flag FRPISETn is set to zero.
  This update prohibition flag FRPSETn is set to 1 in S38 of a 10 ms job shown in FIG. That is, it is set to 1 in the first 10 ms job after generation of the reference crank angle signal REF, and is set to 0 by regarding the end of fuel injection by ignition. However, at the time of rapid deceleration, it is set to 1 in S44 described later of the REF job in FIG.
[0035]
  FIG. 6 shows a scheduled job for calculating the fuel injection amount, specifically a 10 ms job.
  In S31, first, the cylinder number n is set to 1.
  In S32, in order to calculate the target equivalent ratio (= 14.6 / target air-fuel ratio), the basic target equivalent ratio TFBYA0 is set according to the engine operating state (Ne, Tp), and the torque correction amount PIPER is read and corrected. Thus, the target equivalent ratio TFBYA = TFBYA0 × PIPER is calculated.
[0036]
  In S33, the basic fuel injection amount Tp corresponding to the cylinder intake air amount is subjected to various corrections by the target equivalent ratio TFBYA and the like, and the final fuel injection amount (pulse width) TI is calculated by the following equation. This portion corresponds to time synchronous fuel injection amount calculation means.
      TI = Tp × KTR × TFBYA × α × αm + Ts
  However, KTR is a transient correction coefficient, α is an air-fuel ratio feedback correction coefficient, αm is a learning correction coefficient, and Ts is an invalid injection amount (invalid pulse width).
[0037]
  In S34, it is determined whether or not the update prohibition flag FRPSETn = 1. If NO (FRPSETn = 0), the process proceeds to S35.
  In S35, the fuel injection amount TI calculated in S33 is set / updated as the fuel injection control output TISETSn for each cylinder, and set in the output register for injection time control for each cylinder. This portion corresponds to fuel injection control output setting means.
[0038]
  If YES (FRPSETn = 1), updating is prohibited, so S35 is not executed, and the flag immediately after REF FAPPFSTn is set to 0 in S36. Therefore, S34 corresponds to update permission / prohibition means.
  After S35 or S36, the process proceeds to S37.
  In S37, it is determined whether or not the flag immediately after REF FAPPFSTn = 1. Only in the case of YES (flag FAPPFSTn = 1), the update prohibition flag FRPSETn is set to 1 in S38.
[0039]
  Thereafter, in S39, the cylinder number n is incremented by 1, and in S40, it is determined whether or not the cylinder number n exceeds the number of cylinders.
  If NO (n ≦ number of cylinders), the process returns to S32 and the same process is repeated. If YES (n> number of cylinders), the process is terminated.
  Next, the processing (S41 to S44) at the time of the rapid deceleration torque correction request of the REF job in FIG.
[0040]
  If it is determined in S17 whether or not the vehicle is suddenly decelerating (that is, a request for torque correction during sudden deceleration), if YES (during sudden deceleration), S41 to S44 are executed.
  In S41, as in S32, in order to calculate the target equivalent ratio (= 14.6 / target air-fuel ratio), the basic target equivalent ratio TFBYA0 is set according to the engine operating state (Ne, Tp), and the torque correction amount PIPER is read. Thus, the target equivalent ratio TFBYA = TFBYA0 × PIPER is calculated with correction.
[0041]
  In S42, as in S33, the basic fuel injection amount Tp corresponding to the cylinder intake air amount is subjected to various corrections by the target equivalent ratio TFBYA and the like, and the final fuel injection amount (pulse width) TI is calculated by the following equation. To do. This part corresponds to the sudden deceleration fuel injection amount calculation means.
      TI = Tp × KTR × TFBYA × α × αm + Ts
  However, KTR is a transient correction coefficient, α is an air-fuel ratio feedback correction coefficient, αm is a learning correction coefficient, and Ts is an invalid injection amount (invalid pulse width).
[0042]
  In S43, as in S35, the fuel injection amount TI calculated in S42 is set / updated as the fuel injection control output TISETn for each cylinder, and set in the output register for injection time control for each cylinder. This part corresponds to the fuel injection control output setting means together with S35.
  In S44, as in S38, the update prohibition flag FRPSETn is set to 1.
[0043]
  Next, the operation will be described.
  First, referring to the timing chart of FIG. 7, the operation at normal time (other than during sudden deceleration) will be described.
  Before the generation of the reference crank angle signal REF, the flag immediately after REF FAPPFSTn = 0 and the update prohibition flag FRPISETn = 0. When the 10 ms job of FIG. 6 is executed, S32 → S33 → S34 → S35 → S37 → S39 Execute. Accordingly, the fuel injection amount TI is calculated in S32 and 33, and the fuel injection amount TI is set / updated as the fuel injection control output TSETSn in S35. However, the torque correction amount PIPER used in S32 is calculated by the REF job when the previous reference crank angle signal REF is generated. The fuel injection amount TI calculated at this time is used to search for the injection timing IT and the ignition timing ADV. This is because a counter for controlling the injection timing IT and the ignition timing ADV starts with the generation of the reference crank angle signal REF as a trigger.
[0044]
  Due to the generation of the reference crank angle signal REF near the intake valve closing timing (IVC), the latest torque correction amount PIPER is calculated in the REF job of FIG. At this time, the flag immediately after REF FAPPFSTn = 1 is set.
  In the first 10 ms job (FIG. 6) after the generation of the reference crank angle signal REF, since the flag immediately after REF FAPPFSTn = 1, the processing is executed in the order of S32 → S33 → S34 → S35 → S37 → S38 → S39. Accordingly, the fuel injection amount TI is calculated in S32 and 33, and the fuel injection amount TI is set / updated as the fuel injection control output TSETSn in S35. At this time, the torque correction amount PIPER used in S32 is the latest value calculated in the immediately preceding REF job. At this time, the update prohibition flag FRPSETn = 1 is set in S38.
[0045]
  In the second 10 ms job (FIG. 6) after the generation of the reference crank angle signal REF, because the update prohibition flag FRPSETn = 1 (and because the REF immediately after flag FPPFSTn = 0 becomes halfway), S32 → S33 → S34 → S36. Execute in order of → S37 → S39. Therefore, although the fuel injection amount TI is calculated in S32 and 33, S35 is not executed, so the fuel injection control output TISETn is not updated.
[0046]
  Similarly, after the fuel injection is completed, the fuel injection control output TISETSn is not updated until the update prohibition flag FRPISETn = 0 by the ignition job in FIG. Therefore, fuel is injected with the fuel injection control output TISETSn set in the first 10 ms job after the generation of the reference crank angle signal REF.
  Therefore, taking in the latest torque correction amount PIPER in the REF job, the fuel injection amount TI calculated in the first 10 ms job after the REF job is used as the fuel injection control output TISETSn, and the cylinder intake air at the intake valve closing timing is approximately Fuel injection corresponding to the amount becomes possible.
[0047]
  Next, the operation during sudden deceleration will be described.
  At the time of sudden deceleration, the latest torque correction amount PIPER is calculated in the REF job of FIG. 4 by the generation of the reference crank angle signal REF near the intake valve closing timing (IVC) (S13 to S16), and thereafter at S17. Since it is determined that the vehicle is suddenly decelerating, S41 to S44 are executed.
[0048]
  That is, the latest torque correction amount PIPER is taken in, the fuel injection amount TI is calculated (S41, S42), and this is set and updated as the fuel injection control output TSETSn (S43). Then, the subsequent update of the fuel injection control output TISETn is prohibited (S44).
  Therefore, at the time of sudden deceleration, the latest torque correction amount PIPER is reflected in the REF job in synchronization with the generation of the reference crank angle signal REF even if the 10 ms job does not enter between the reference crank angle signal REF and the fuel injection. Thus, the fuel injection amount TI is calculated and this is used as the fuel injection control output TISETSn. Therefore, engine stall can be prevented by quick torque correction.
[0049]
  In this case, the calculation load increases by calculating the fuel injection amount TI in the REF job, but the influence is small because it is only during sudden deceleration.
  FIG. 8 shows a case where there is no sudden deceleration torque correction request. At low speed (for example, less than 800 rpm), as shown in FIG. 8A, at least a 10 ms job is required between the reference crank angle signal REF and fuel injection. Once, the fuel injection control output TISETSn is allowed to be updated until the first 10 ms job after the reference crank angle signal REF. At a high rotation (for example, 800 rpm or more), as shown in FIG. 8B, a 10 ms job may not enter even once between the reference crank angle signal REF and fuel injection, and the latest torque correction amount PIPER is There is a case where it is not reflected, but there is no problem because a high response is not required unless it is suddenly decelerated.
[0050]
  FIG. 9 shows a case where there is a request for torque correction during sudden deceleration. At low speed (for example, less than 800 rpm), as shown in FIG. 9A, at least a 10 ms job is required between the reference crank angle signal REF and fuel injection. Although it enters once, the fuel injection amount TI reflecting the latest torque correction amount PIPER is calculated in the REF job, and set as the fuel injection control output TISETn. At high speed (for example, 800 rpm or more), as shown in FIG. 9B, a 10 ms job may not be entered even once between the reference crank angle signal REF and the fuel injection. Since the fuel injection amount TI reflecting the correction amount PIPER is calculated and set as the fuel injection control output TISETSn, engine stall at the time of sudden deceleration can be prevented.
[0051]
  In the present embodiment, the basic fuel injection amount Tp is calculated by a 4 ms job, but may be calculated by the same job (for example, a 10 ms job) as the fuel injection amount TI.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing the configuration of the present invention.
FIG. 2 is a system diagram of an internal combustion engine showing an embodiment of the present invention.
FIG. 3 is a flowchart of a 4 ms job.
FIG. 4 is a flowchart of a REF job.
FIG. 5 is a flowchart of an ignition job.
FIG. 6 is a flowchart of a 10 ms job.
FIG. 7 is a timing chart showing the normal operation
[Figure 8] Timing chart when there is no torque correction request for sudden deceleration
[Fig. 9] Timing chart when there is a torque correction request for sudden deceleration
[Explanation of symbols]
              1 Internal combustion engine
              3 Intake passage
              4 Electric throttle valve
              5 Fuel injection valve
              6 Spark plug
              21, 22 Crank angle sensor
              23 Air flow meter
              24 accelerator sensor

Claims (4)

In a direct-injection spark-ignition internal combustion engine that includes a fuel injection valve that directly injects fuel into the combustion chamber and injects fuel after the intake valve closing timing,
An intake valve closing timing signal generating means for generating a signal representative of the intake valve closing timing;
Torque correction amount calculation means for calculating a torque correction amount based on a torque correction request for fuel injection amount calculation in synchronization with the generation of a signal representative of the intake valve closing timing;
Time-synchronized fuel injection that calculates the fuel injection amount by performing at least a correction by the torque correction amount calculated by the torque correction amount calculation means with respect to the basic fuel injection amount based on the cylinder intake air amount every predetermined time A quantity calculating means;
Sudden deceleration state detection means for detecting a sudden deceleration state;
The torque correction amount calculated by the torque correction amount calculation means at least with respect to the basic fuel injection amount based on the cylinder intake air amount in synchronization with the generation of the signal representative of the intake valve closing timing when the sudden deceleration state is detected. subjected to correction by a rapid deceleration fuel injection amount calculating means for calculating a fuel injection amount,
Fuel injection control output setting means for setting the fuel injection amount calculated by the time-synchronized fuel injection amount calculation means or the rapid deceleration fuel injection amount calculation means as a fuel injection control output;
The fuel injection control is performed with the fuel injection amount obtained by the calculation of the fuel injection amount by the time-synchronized fuel injection amount calculation means for the first time after the generation of the signal representative of the intake valve closing timing, except when the sudden deceleration state is detected. Updating of the fuel injection control output by the output setting means is permitted, and updating of the fuel injection control output is prohibited thereafter until the end of fuel injection, and when the sudden deceleration state is detected, the fuel by the sudden deceleration fuel injection amount calculating means is detected. An update permission that permits updating of the fuel injection control output by the fuel injection control output setting means with the fuel injection amount obtained by calculation of the injection amount and prohibits updating of the fuel injection control output thereafter until the end of fuel injection. Prohibited means,
A fuel injection control device for a direct injection spark ignition internal combustion engine.   The intake valve closing timing signal generating means is reference crank angle signal generating means, and the generation timing of the reference crank angle signal generated for each crank angle of 720 ° / number of cylinders in synchronism with engine rotation is matched with the intake valve closing timing. 2. The fuel injection control device for a direct injection spark ignition type internal combustion engine according to claim 1, wherein the reference crank angle signal is used as a signal representative of the intake valve closing timing.   The torque correction amount calculation means compares the actual engine speed with the target speed, and calculates a torque correction amount to correct the air-fuel ratio in a direction to reduce the rotational speed deviation based on the comparison result. 3. The fuel injection control device for a direct injection spark ignition type internal combustion engine according to claim 1 or 2.   The cylinder intake air amount calculation means includes means for delaying the intake air amount detected based on a signal from an air flow meter disposed in the intake passage and calculating the cylinder intake air amount. The fuel injection control device for a direct-injection spark-ignition internal combustion engine according to any one of claims 1 to 3.

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