JP5093050B2 - Direct injection spark ignition engine fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control device for a direct injection spark ignition engine.

In a direct-injection spark-ignition four-cylinder engine, when switching from stratified combustion injection to homogeneous combustion injection, the first cylinder (# 1 cylinder) of homogeneous combustion is injected more than the injection of the last cylinder (# 2 cylinder) of stratified combustion. When the injection start timing becomes earlier, there is one that corrects the injection start timing of the first cylinder (# 1 cylinder) of homogeneous combustion to the advance side (see Patent Document 1).
Japanese Patent Laid-Open No. 10-61463

  By the way, among the direct-injection spark-ignition engines, in the 4-cylinder engine, the 6-cylinder engine, the 8-cylinder engine, and the 12-cylinder engine, the injection start timing of the homogeneous combustion has passed at the timing when there is a request for switching to the homogeneous combustion. Two or more cylinders may be created. In this case, the cylinder that has passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion has passed is synchronized with the reference signal (REF signal) immediately after the timing when the request for switching to the homogeneous combustion is requested. It is conceivable to perform fuel injection and to perform homogeneous combustion injection from the next cylinder that has completed all fuel injection synchronized with these reference signals.

  Here, the direct-injection spark-ignition engine has an injector that can inject fuel directly into the combustion chamber for each cylinder. However, the injector needs a higher voltage than the type that injects into the intake port. Therefore, it is necessary to ensure a sufficient charging time for the injector drive circuit. Further, the same number of injector drive circuits as the number of cylinders are not provided, and only one injector drive circuit is provided for the entire engine. Therefore, for all cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request for switching to homogeneous combustion has been made, in synchronization with the reference signal immediately after the timing when the request for switching to homogeneous combustion is requested, If fuel injection is performed in synchronism with the same reference signal for a plurality of cylinders, the injection start timing overlaps. As a result, the charge amount is insufficient to drive two or more injectors with the charge amount of the injector drive circuit, and the injection start timing of the homogeneous combustion has passed at the timing when there is a request for switching to the homogeneous combustion. There is a cylinder in which the fuel injection amount is insufficient due to insufficient valve opening time in any of the cylinders in the cylinder or in all the cylinders that have passed the injection start timing of homogeneous combustion at the timing when switching to homogeneous combustion is requested This may cause a misfire, and the misfire will deteriorate the drivability and exhaust emissions.

  Therefore, the present invention starts the injection while ensuring the charging time of the injector drive circuit even when there are two or more cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made. An object of the present invention is to provide a device capable of performing fuel injection that does not overlap in time.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes an injector capable of directly injecting fuel into a combustion chamber for each cylinder, and a reference signal (REF signal) generated at a predetermined crank angle position for each cylinder, and the reference signal (REF signal) for each cylinder. After the elapse of the first predetermined crank angle interval from the input timing of the engine, and after the elapse of the second predetermined crank angle interval larger than the first predetermined crank angle interval from the input timing of the reference signal for each cylinder after the elapse of the first predetermined crank angle interval. The injection start time of stratified combustion is set in advance, and when switching to stratified combustion is requested, switching from homogeneous combustion injection to stratified combustion injection is performed, and when stratified combustion is requested to switch to homogeneous combustion. In a fuel injection control device for a direct-injection spark-ignition engine that switches from injection to homogeneous combustion injection, there is a request to switch to homogeneous combustion. When there are a plurality of cylinders that have passed the homogeneous combustion injection start timing, the first cylinder in the firing order (the first cylinder in FIG. 6) out of the multiple cylinders that have passed the homogeneous combustion injection start timing. ) Injection start timing is set to the input timing of the reference signal (the REF signal for the second cylinder in FIG. 6) immediately after the request for switching to the homogeneous combustion, and the injection start timing of the homogeneous combustion has passed. The injection start timing of the next cylinder of the plurality of cylinders (the seventh cylinder in FIG. 6) is the reference signal after the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made (in FIG. 6, the first cylinder REF). Signal) and the injection start timing of the second and subsequent cylinders (the eighth cylinder in FIG. 6) in the ignition order among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, Serial and injection start timing of the first cylinder (6 1 cylinder), set the time of an intermediate between the injection start timing of the next cylinder of the plurality of cylinders (Fig. 6, 7 cylinder).

  The present invention also includes an injector capable of directly injecting fuel into the combustion chamber for each cylinder, and a reference signal (REF signal) generated at a predetermined crank angle position for each cylinder, and the reference signal (REF signal) for each cylinder. ) After the elapse of the first predetermined crank angle interval from the input timing of), the injection start timing of homogeneous combustion, and the elapse of the second predetermined crank angle interval greater than the first predetermined crank angle interval from the input timing of the reference REF signal for each cylinder The later is set in advance as the start timing of stratified combustion, switching from homogeneous combustion injection to stratified combustion injection at the timing when switching to stratified combustion is requested, and stratified at the timing when switching to homogeneous combustion is requested In the fuel injection control device of a direct injection spark ignition engine for switching from combustion injection to homogeneous combustion injection, switching to the homogeneous combustion When there are multiple cylinders that have passed the injection start timing of homogeneous combustion at the requested timing, and when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than the predetermined value, this homogeneous combustion injection Among the plurality of cylinders that have passed the start timing, the reference signal (in FIG. 6) immediately after the timing at which the injection start timing of the first cylinder in the ignition order (the first cylinder in FIG. 6) is switched to the homogeneous combustion is requested. The second cylinder REF signal) is set to the input timing, and the injection start timing of the next cylinder (the seventh cylinder in FIG. 6) that has passed the homogeneous combustion injection start timing is set to the homogeneous combustion. The input timing is set to the input timing after the reference signal immediately after the timing when the switching request is made (in FIG. 6, the REF signal for the first cylinder), and the homogeneous combustion injection start timing has passed. Among the plurality of cylinders, the injection start timing of the second and subsequent cylinders (8th cylinder in FIG. 6) in the ignition order, the injection start timing of the first cylinder (1st cylinder in FIG. 6), and the plurality of cylinders A cylinder that is set to an intermediate time from the injection start timing of the cylinder next to the cylinder (cylinder No. 7 in FIG. 6) and has passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made And when the influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is equal to or less than a predetermined value, among the plurality of cylinders that have passed the injection start timing of this homogeneous combustion, the first in the ignition order Is set to the input timing of the reference signal (REF signal for the second cylinder in FIG. 6) immediately after the request for switching to the homogeneous combustion is made. Combustion injection start time The reference signal next to the reference signal immediately after the timing at which the request to switch to the homogeneous combustion is made for the injection start timing of the second and subsequent cylinders (8th cylinder in FIG. 6) among the plurality of cylinders that have passed Thereafter, the input timing is set (the REF signal for the first cylinder in FIG. 6).

According to the present invention, an injector capable of directly injecting fuel into a combustion chamber for each cylinder and a reference signal generated at a predetermined crank angle position for each cylinder are provided, and the first is based on the input timing of the reference signal for each cylinder. After the elapse of a predetermined crank angle interval, the homogeneous combustion injection start timing, and after the elapse of a second predetermined crank angle interval greater than the first predetermined crank angle interval from the input timing of the reference signal for each cylinder, the stratified combustion injection start timing Is set in advance, switching from homogeneous combustion injection to stratified combustion injection at the timing when switching to stratified combustion is requested, and stratified combustion injection to homogeneous combustion injection at the timing when switching to homogeneous combustion is requested In a fuel injection control device for a direct-injection spark-ignition engine that switches to If there is more than one cylinder that is past the injection start time,
Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made, The injection start timing of the next cylinder of the plurality of cylinders that has passed the injection start timing of the homogeneous combustion is set to the input timing after the reference signal next to the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made. , Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timing of the second and subsequent cylinders in the ignition order, the injection start timing of the first cylinder, and the next cylinder of the plurality of cylinders Because it is set to an intermediate time from the injection start time, it is possible to ensure the voltage boost time of the injector drive circuit while preventing simultaneous injection in multiple cylinders with different ignition orders Therefore, even when there are two or more cylinders that have passed the start timing of homogeneous combustion at the timing when there was a request to switch to homogeneous combustion, it is possible to reduce variations in fuel injection amount due to insufficient injector drive current Thus, the operability at the time of switching from stratified combustion to homogeneous combustion can be improved.

  Further, in order to perform fuel injection at the intermediate timing, that is, to perform injection other than the reference signal synchronous injection, it is necessary to start a timer from the input timing of the reference signal. Since only one timer is required to be started at the input timing of the reference signal, the calculation load is not deteriorated.

  In addition, according to the present invention, an injector capable of directly injecting fuel into a combustion chamber for each cylinder and a reference signal generated at a predetermined crank angle position for each cylinder are provided, and the reference signal is input from the input timing of the reference signal for each cylinder. After the passage of one predetermined crank angle section, the injection start timing of homogeneous combustion, and the injection of stratified combustion after the passage of a second predetermined crank angle section larger than the first predetermined crank angle section from the input timing of the reference REF signal for each cylinder The start time is set in advance, switching from homogeneous combustion injection to stratified combustion injection at the timing when switching to stratified combustion is requested, and stratified combustion injection to homogeneous combustion at the timing when switching to homogeneous combustion is requested In the fuel injection control device for a direct-injection spark-ignition engine that switches to the other injection, the timing when the switching request to the homogeneous combustion is requested When there are multiple cylinders that have passed the homogeneous combustion injection start timing and when the influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than the specified value, this homogeneous combustion injection start timing has passed The injection start timing of the first cylinder in the ignition sequence among the plurality of cylinders is set to the input timing of the reference signal immediately after the request for switching to the homogeneous combustion, and the injection start timing of the homogeneous combustion has passed. The injection start timing of the next cylinder of the plurality of cylinders is set to an input timing after the reference signal next to the reference signal immediately after the request for switching to the homogeneous combustion, and the injection start timing of the homogeneous combustion is passed. The injection start timings of the second and subsequent cylinders in the firing order among the plurality of cylinders that are present, the injection start timing of the first cylinder, and the next cylinder of the plurality of cylinders When there are a plurality of cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the switching to the homogeneous combustion is requested and the homogeneity of the mixture in the combustion chamber is When the degree of influence on torque fluctuation is equal to or less than a predetermined value, a request to switch the injection start timing of the first cylinder in the ignition sequence to the homogeneous combustion among the plurality of cylinders that have passed the injection start timing of this homogeneous combustion The reference signal input timing is set immediately after the occurrence of the combustion, and the injection start timings of the second and subsequent cylinders in the ignition order among the plurality of cylinders that have passed the homogeneous combustion injection start timing are switched to the homogeneous combustion. Since it is set to the input timing after the reference signal immediately after the requested timing, it prevents simultaneous injection in multiple cylinders with different ignition orders. In addition, since the voltage boost time of the injector drive circuit can be secured, the homogeneous combustion injection is performed at the timing when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than a predetermined value and there is a request to switch to homogeneous combustion Injection of homogeneous combustion when there are multiple cylinders that have passed the start time and when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value and when switching to homogeneous combustion is requested It is possible to reduce the variation in fuel injection amount due to insufficient injector drive current in any case where there are multiple cylinders that have passed the start time, and the operability when switching from stratified combustion to homogeneous combustion can be reduced. When the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than the predetermined value and there is a request to switch to homogeneous combustion In the case where a plurality cylinder has passed the injection start timing of the homogeneous combustion is grayed, it is possible to perform switching to the injection to the homogeneous combustion even more at an earlier timing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a fuel injection control device for a direct injection spark ignition engine according to a first embodiment of the present invention.

  In FIG. 1, a throttle valve 5 for controlling the intake air amount is installed upstream of the intake collector 7 of the engine 1. The opening degree of the throttle valve 5 is controlled by a step motor 10 that operates according to a signal from the engine controller 15.

  In the combustion chamber 8 a of the engine 1, an injector (fuel injection valve) 13 that can inject fuel directly into the combustion chamber 8 a together with the ignition plug 24 is installed for each cylinder.

  The injector 13 is energized to the solenoid by a fuel injection pulse signal output at a predetermined timing from the engine controller 15 in synchronism with the engine rotation, and is opened. The fuel tank is discharged from the fuel pump 12 and adjusted to a predetermined pressure. The fuel from 11 is injected.

  An exhaust purification catalyst 22 is provided in the exhaust passage 19 of the engine 1.

  The engine controller 15 detects an accelerator opening detected by an accelerator pedal sensor (not shown), an engine speed detected by a crank angle sensor 16, an intake air flow detected by an air flow meter 3, and a throttle sensor 18. The engine cooling water temperature detected by the throttle opening and the water temperature sensor 25 is input.

  The engine controller 15 sets a combustion system (homogeneous combustion, stratified combustion) based on the engine operating conditions detected from these input signals, and according to this, the opening of the throttle valve 5 and the fuel injection of the injector 13 are set. The timing, the fuel injection amount from the injector 13, and the ignition timing of the spark plug 24 are controlled.

  In the case of the homogeneous combustion, the air-fuel ratio is controlled to the stoichiometric air-fuel ratio (A / F = 14.6), while in order to ensure the homogenization time of the air-fuel mixture, early timing, that is, the intake stroke of each cylinder (more Specifically, the fuel is injected into the combustion chamber 8a in the first half of the intake stroke). In contrast, in the case of stratified combustion, the air-fuel ratio is controlled to be lean (A / F = 30 to 40), while the fuel is concentrated around the spark plug 24 near the ignition timing, that is, the compression stroke ( More specifically, fuel is injected into the combustion chamber 8a in the first half of the compression stroke before ignition.

  Here, the demand for stratified combustion is, for example, at a low rotational speed or at the start of the engine. This requires stratified combustion in order to prevent pre-ignition at low rotational speeds. Further, stratified combustion is also required for warming up the catalyst 22 at the time of engine cold start. For this reason, a request flag is introduced, and when the request flag = 1, stratified combustion is requested. That is, switching from homogeneous combustion to stratified combustion by switching the request flag from zero to 1 and switching from stratified combustion to homogeneous combustion by switching the request flag from 1 to zero. Hereinafter, the case where the request flag is a pre-ignition avoidance request flag will be described.

  When switching from homogeneous combustion injection to stratified combustion injection, there is no problem because the injection start timing can be simply delayed from the first half of the intake stroke to the first half of the compression stroke. However, when switching from stratified combustion injection to homogeneous combustion injection, there may be two or more cylinders that have passed the injection start timing of homogeneous combustion at the timing when the switch to homogeneous combustion is requested. The case where two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is specifically made will be described with reference to FIG. 2A. FIG. 2A shows a V-type 8-cylinder engine. When the pre-ignition avoidance request flag (abbreviated as “pre-ignition avoidance request flag” in the figure) is switched from 1 to zero, the current control determines the injection start timing of each cylinder before and after the change of the value of this request flag. It shows what happens. Here, the pre-ignition avoidance request flag is a flag which becomes 1 to prevent pre-ignition at a low rotation speed. When it is not at the low rotation speed, pre-ignition does not occur, and therefore the pre-ignition avoidance request flag is reset to zero.

  When the ignition order of the V-type 8-cylinder engine is No. 1-8, No. 7, No. 7, No. 3, No. 6, No. 5, No. 4, No. 2, and No. 2. As shown in FIG. That is, as shown in FIG. 9, the strokes of the cylinders adjacent in the ignition order are shifted by 90 ° in crank angle. Further, as shown in the upper part of FIG. 9, a reference signal for each cylinder (hereinafter referred to as “REF signal”) is generated at a predetermined crank angle position in the initial stage of the compression stroke of each cylinder. More specifically, focusing on the first cylinder, the REF signal for the second cylinder is 170 ° to 160 ° (crank angle) from the compression stroke end timing (compression top dead center) of the first cylinder. The REF signal for the first cylinder is 80 ° to 70 ° (crank angle) from the end of the compression stroke, and in other words, 2 at the timing when 10 ° to 20 ° (crank angle) has elapsed from the start of the compression stroke of the first cylinder. The first cylinder REF rises at the timing when 100 ° to 110 ° (crank angle) has elapsed from the compression stroke start timing of the first cylinder. “Initial compression stroke” means that the crank angle is 10 ° to 20 ° from the compression stroke start timing.

  Here, the rising timing of the REF signal is used as the starting point of the injection start timing and the ignition timing. However, the present invention is not limited to this, and the REF signal falling timing may be used as the starting point of the injection start timing. If the rising timing and falling timing of the REF signal are collectively referred to as “input timing” of the REF signal, the input timing of the REF signal is used as the starting point of the injection start timing and the ignition timing. For example, if the crank angle section from the rising timing of the REF signal to the injection start timing of stratified combustion is defined as a “second predetermined crank angle section”, the second predetermined crank angle section is the second based on the engine speed at that time. It is converted into the time corresponding to the predetermined crank angle section. In FIG. 2A, for example, in the No. 4 cylinder, a timer is started at the rising timing of the No. 5 cylinder REF signal, and the injector of the No. 4 cylinder is driven when the timer value coincides with the second predetermined crank angle section equivalent time. Is injected. In the second cylinder, the same timer is started at the rising timing of the fourth cylinder REF signal, and when the timer value coincides with the second predetermined crank angle section equivalent time, the injector of the second cylinder is driven and injection is performed. Done.

  On the other hand, assuming that the crank angle section from the rising timing of the REF signal to the injection start timing of the homogeneous combustion is a “first predetermined crank angle section”, the first predetermined crank angle section is the second based on the engine speed at that time. It is converted into the time corresponding to the predetermined crank angle section. In FIG. 2A, for example, in the No. 3 cylinder, the timer is started at the rising timing of the No. 1 cylinder REF signal, and when the timer value coincides with the time corresponding to the first predetermined crank angle section, the No. 3 cylinder injector Is driven to perform injection. In the No. 6 cylinder, the same timer is started at the rising timing of the No. 8 cylinder REF signal, and when the timer value coincides with the time corresponding to the first predetermined crank angle section, the No. 6 cylinder injector is driven and injection is performed. Done.

  In FIG. 2A, if the engine operating condition deviates from the low rotational speed range at the timing t7, the pre-ignition avoidance request flag is switched from 1 to zero at the timing t7. At the timing of t7, the stratified combustion injection in which the injection start timing is in the first half of the compression stroke is finished in the fourth and second cylinders. Therefore, in the ignition order, the injection start timing must be switched to the homogeneous combustion injection in the first half of the intake stroke in the first cylinder and the eighth cylinder after the second cylinder.

  However, since the timings t2 and t5, which are the injection start timings of homogeneous combustion, have already passed for the two cylinders of the first cylinder and the eighth cylinder at the timing of t7, the two cylinders of the first cylinder and the eighth cylinder Then, it is not possible to cause homogeneous combustion injection at the timings t2 and t5.

  Here, when the REF signal (here, the REF signal for the second cylinder) generated immediately after the timing of t7 is referred to as a “reference REF signal”, the reference REF signal of the two cylinders of the first cylinder and the eighth cylinder is changed. It is conceivable that fuel injection is performed at the rising timing (t8). Thus, the fuel injection synchronized with the rising timing of the REF signal is hereinafter referred to as “REF synchronous injection”.

  The drive of the injector 13 in the direct-injection spark ignition engine requires a higher voltage than the type injecting into the intake port, and therefore it is necessary to ensure a sufficient charging time for the injector drive circuit. Here, the “charge time of the injector drive circuit” means the voltage boost time of the injector drive circuit (the minimum time required to boost the voltage of the injector drive circuit to a voltage that guarantees the operation of the injector). That is. The same number of injector drive circuits as the total number (8) of injectors are not provided, and only one injector drive circuit is provided for the entire engine. This is to avoid the increase in cost if the same number of injector drive circuits as the total number (8) of the injectors 13 are provided. For this reason, the injector drive circuit can basically only guarantee the drive of one injector 13 in a charged state. Therefore, as shown in FIG. 2A, when the injection start timings of the two cylinders, the first cylinder and the eighth cylinder, overlap at the timing of t8, charging is required to drive two or more injectors with the charge amount of the injector driving circuit. The amount of fuel injection is insufficient due to the shortage of valve opening time in either one of the injectors for the first cylinder and the injector for the eighth cylinder, or one of the injectors for the eighth cylinder, resulting in a misfire. As a result, drivability and exhaust emission are deteriorated.

  As described above, even when the REF synchronous injection is performed when there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, the same t8 is applied to the plurality of cylinders. If this timing is used, the injection start timing overlaps, the fuel injection amount varies, and the drivability deteriorates.

  Therefore, in order to avoid duplication of injection start timings in a plurality of cylinders, the injection start timing of the eighth cylinder is delayed by the charging time of the injector drive circuit as shown in FIG. 2B, that is, the rising timing of the reference REF signal (t8). It can be considered that the timing (t41) at which the charging time of the injector drive circuit elapses. In this case, it is necessary to start the first timer from the rising timing (t8) of the reference REF signal and determine whether or not the charging time of the injector driving circuit has come. On the other hand, in the seventh cylinder as shown in FIG. 2B, the timing of t9 which is the injection start timing of homogeneous combustion is after the timing of t7 as shown in FIG. 2B, so the pre-ignition avoidance request flag is changed from 1 to zero. Immediately after switching, it is possible to perform homogeneous combustion injection in which the injection start timing is in the first half of the intake stroke. For this reason, in the seventh cylinder, the second timer is started from the rising timing (t8) of the reference REF signal, and it is determined whether or not the time corresponding to the injection start timing of the homogeneous combustion has passed. Necessary. In this way, even if the overlap of the injection start timings in the two cylinders, the first cylinder and the eighth cylinder, is avoided, the injection start timing of the eighth cylinder is only delayed by the charging time of the injector drive circuit. Two timers, the first timer and the second timer, are used from the reference REF signal, and the calculation load of the engine controller 15 is increased.

  2A and 2B are examples in which two cylinders (the first cylinder and the eighth cylinder) that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made. It was. However, the engine in which two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made occurs not only in the 8-cylinder engine but also in the 4-cylinder engine and the 12-cylinder engine. The 6-cylinder engine has not been confirmed. On the other hand, there is an engine in which there are three cylinders that have passed the injection start timing of homogeneous combustion at the timing when there is a request for switching to homogeneous combustion. Specifically, in each of the 6-cylinder, 8-cylinder, and 12-cylinder engines, there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when there is a request for switching to the homogeneous combustion.

  Therefore, in the present invention, as will be described later with reference to FIG. 6, there are two cylinders (the first cylinder and the eighth cylinder) that have passed the injection start timing of the homogeneous combustion at the timing when there is a request for switching to the homogeneous combustion. In this case, the REF signal immediately after the request for switching the injection start timing of the first cylinder (the first cylinder) in the ignition order among the two cylinders that have passed the injection start timing of the homogeneous combustion to the homogeneous combustion. The REF signal synchronous injection set at the rising timing (t8) of the (reference REF signal) is used, and the injection start timing of the next cylinder (the seventh cylinder) after the two cylinders that have passed the injection start timing of the homogeneous combustion is changed to the homogeneous combustion. The REF signal synchronous injection set at the rising timing (t10) of the REF signal (the REF signal for the first cylinder) next to the REF signal immediately after the request for switching is started, and the injection of homogeneous combustion is started Of the two cylinders that have passed the period, the injection start timing of the second cylinder (8th cylinder) in the firing order is the injection start timing (t8) of the first cylinder and the next cylinder of the two cylinders ( It is set to an intermediate time (t41) from the injection start time (t10) of the seventh cylinder).

  However, the first time, which is the time from the injection start timing of stratified combustion immediately before the timing when switching to homogeneous combustion is requested to the rising timing of the REF signal immediately after the timing when switching to homogeneous combustion is requested, is injector driven. If the charging time is less than the circuit, REF signal synchronous injection becomes impossible, and the REF immediately after the timing when the switching request to the homogeneous combustion is requested from the rising timing of the REF signal immediately before the timing when the switching to the homogeneous combustion is requested. If the second time, which is the time until the signal input timing, is less than twice the charging time of the injector drive circuit, it is impossible to set an intermediate time. Take control.

  This will be described in detail with reference to FIGS. 3 to 7. FIGS. 3 to 5 show the connection control until the main control is started, and FIGS. 6 and 7 show the main control.

  3 to 7, for convenience of explanation, the timing at which the pre-ignition avoidance request flag is switched from 1 to zero is the same as that in FIG. 2, and accordingly, when switching from stratified combustion injection to homogeneous combustion injection. The injection start timing is newly set for the first cylinder and the eighth cylinder.

  First, FIG. 3 shows the input timing (t8) from the rising timing (t4) of the REF signal (4th cylinder REF signal) immediately before the request for switching to homogeneous combustion to the reference REF signal (2nd cylinder REF signal). ) The second time (abbreviated as “REF-REF” in the drawing) is longer than the charging time of the injector drive circuit × 2 and the injection of the stratified combustion immediately before the request for switching to the homogeneous combustion is made This is a case where the first time, which is the time from the start timing (t6) to the rising timing (t8) of the reference REF signal (REF signal for the second cylinder) does not exceed the charging time of the injector drive circuit. Here, the second time depends on the engine speed Ne, and the second time becomes shorter as the engine speed Ne becomes higher. Therefore, the second time is equal to or less than the charging time of the injector driving circuit × 2 at the high rotation speed. Further, the charging time Tchg of the injector drive circuit is determined in advance according to the specifications of the injector drive circuit.

  In this case, in order to prevent the injection start timings of the first cylinder and the eighth cylinder from overlapping, the first cylinder and the eighth cylinder are set to REF signal synchronous injection with different timings. That is, in the eighth cylinder, fuel injection is started at the rising timing (t10) of the first cylinder REF signal. However, in the first cylinder, since the time from the timing t7 to the rising timing (t8) of the reference REF signal (REF signal for the second cylinder) is short, the injector drive circuit cannot be charged in time, so the reference REF signal (for the second cylinder) The fuel injection cannot be started at the rising timing (t8) of the (REF signal). Therefore, in the first cylinder, fuel injection is performed at timing t21 when the charging time Tchg of the injector drive circuit elapses from timing t8. At this time, the injection start timing of the first cylinder is the first half of the compression stroke, and the injection start timing of the eighth cylinder is the initial compression stroke (see also FIG. 9). The subsequent control is transferred from the seventh cylinder to the main control shown in FIGS.

  FIG. 4 shows the timing from the rising timing (t4) of the REF signal (4th cylinder REF signal) immediately before the request for switching to homogeneous combustion to the input timing (t8) of the reference REF signal (2nd cylinder REF signal). The reference time REF signal (for the second cylinder) from the injection start timing (t6) of the stratified combustion immediately before the timing at which the second time is the charging time of the injector drive circuit × 2 or less and the switching request to the homogeneous combustion is requested This is a case where the first time which is the time until the rising timing (t8) of the (REF signal) does not exceed the charging time of the injector driving circuit. In this case, since the REF signal synchronous injection cannot be performed, the time from the start timing of the stratified combustion to the rising timing of the REF signal immediately after the timing (t7) when the request for switching to the homogeneous combustion is made And the fourth time, which is the time from the rising timing of one REF signal to the rising timing of the next REF signal, until the third time exceeds the charging time of the injector driving circuit, or Until the fourth time exceeds the charging time x 2 of the injector drive circuit, the injection of stratified combustion is continued in each cylinder immediately after the request for switching to homogeneous combustion. That is, in the first cylinder, the eighth cylinder, the seventh cylinder, the third cylinder,..., Stratified combustion is injected at each timing t31, t32, t33, t34,.

  FIG. 5 shows from the rising timing (t4) of the REF signal (4th cylinder REF signal) immediately before the request for switching to homogeneous combustion to the input timing (t8) of the reference REF signal (2nd cylinder REF signal). The reference time REF signal (for the second cylinder) from the injection start timing (t6) of the stratified combustion immediately before the timing at which the second time is the charging time of the injector drive circuit × 2 or less and the switching request to the homogeneous combustion is requested This is a case where the first time, which is the time until the rise timing (t8) of the (REF signal), is equal to or longer than the charging time of the injector driving circuit. In this case, since the REF signal synchronous injection can be performed, the timing from the rising timing of one REF signal to the rising timing of the next REF signal after the timing (t7) when switching to homogeneous combustion is requested. The fourth time is calculated, and the REF signal synchronous injection is continued in each cylinder immediately after the timing when the switching to the homogeneous combustion is requested until the fourth time exceeds the charging time x 2 of the injector drive circuit. That is, the rising timing of the reference REF signal (t8) in the first cylinder, the rising timing (t10) of the REF signal for the first cylinder in the eighth cylinder, and the rising timing (t12) of the REF signal for the eighth cylinder in the seventh cylinder. ) To inject fuel. At this time, the injection start timings of the first cylinder, the eighth cylinder, and the seventh cylinder are all in the initial stage of the compression stroke (see also FIG. 9).

  Thus, from the seventh cylinder in the case of FIG. 3, the third time in the case of FIG. 4 exceeds the charging time of the injector driving circuit, or the fourth time is the charging time of the injector driving circuit of the injector driving circuit. In the case of FIG. 5, when the time exceeds × 2, the fourth time shifts to the control of FIGS. 6 and 7 when the charging time of the injector drive circuit exceeds × 2.

  6 and 7 show the case where the fourth time exceeds the charging time x2 of the injector driving circuit and the third time exceeds the charging time of the injector driving circuit after the timing (t7) when the switching request to the homogeneous combustion is requested Represents. 6 and 7 show that when the first time exceeds the charging time of the injector driving circuit × 2 and the third time exceeds the charging time of the injector driving circuit, in other words, from the injection of stratified combustion In the case of switching to the combustion injection, the case where the setting of the fuel injection start time is not limited as shown in FIGS.

  FIG. 6 and FIG. 7 are the main control. Here, it is determined whether the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is larger than a predetermined value, and the mixing in the combustion chamber 8a is performed. The control of FIG. 6 is performed when the influence degree of the homogeneity of the gas on the torque fluctuation is larger than the predetermined value, and the control of FIG. 7 is performed.

  More specifically, since the gas flow in the combustion chamber 8a becomes stronger as the engine speed increases, the degree of influence on the torque fluctuation is small even if the homogeneity of the air-fuel mixture in the combustion chamber 8a decreases. Conceivable. Therefore, in the same 8-cylinder engine, the case where the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is larger than the predetermined value specifically means a low rotational speed region where the engine rotational speed is smaller than the threshold value. On the contrary, the case where the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is a predetermined value or less is a high rotation speed region where the engine rotation speed is equal to or greater than a threshold value.

  Here, a description will be given of a case where the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation due to the difference in the engine rotational speed Ne is greater than a predetermined value and less than a predetermined value. It is not limited to. For example, when an engine with a small number of cylinders such as a 4-cylinder engine is compared with an engine with a large number of cylinders such as a 6-cylinder, 8-cylinder, or 12-cylinder engine under the same operating conditions (same rotational speed), The influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is greater in the engine with fewer engines than in the engine with more cylinders. Therefore, when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is larger than a predetermined value, specifically, an engine (four-cylinder engine) in which the number of cylinders is equal to or less than a cylinder number threshold (for example, four). On the contrary, when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is less than a predetermined value, the engine (6 Cylinder engine, 8-cylinder engine, 12-cylinder engine).

  A description will be given from FIG. 6 employed when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is greater than a predetermined value. In FIG. 6, the first cylinder and the eighth cylinder are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made. In this case, the first cylinder (the first cylinder in the ignition order among the two cylinders that have passed the injection start timing of the homogeneous combustion) is set as the REF signal synchronous injection. In addition, the seventh cylinder (the cylinder next to the two cylinders that have passed the injection start timing of homogeneous combustion) is not the cylinder that has passed the injection start timing of homogeneous combustion at the timing when there was a request to switch to homogeneous combustion. For the seventh cylinder, the REF signal synchronous injection is shifted in timing from the REF signal synchronous injection of the first cylinder. That is, fuel injection is started at the rising timing (t8) of the reference REF signal (REF signal for the second cylinder) in the first cylinder and at the rising timing (t10) of the REF signal for the first cylinder in the seventh cylinder. At this time, the injection start timing of the first cylinder is at the beginning of the compression stroke from FIG. 9, and the injection start timing of the seventh cylinder is at the latter half of the intake stroke from FIG.

  On the other hand, the injection start timing of the eighth cylinder (the second cylinder in the ignition order among the two cylinders that have passed the injection start timing of homogeneous combustion) is the injection start timing of the first cylinder and the injection start of the seventh cylinder. Set the time in between the time. That is, in the eighth cylinder, fuel injection is started at an intermediate timing between the timing t8 and the timing t10. Here, “intermediate timing” does not mean only the middle timing between the timing of t8 and the timing of t10. Theoretically, as long as it is between the timing of t8 and the timing of t10, it may be close to t8 or vice versa. Actually, the crank angle interval between the rising timing (t8) of the second cylinder REF signal and the rising timing (t10) of the first cylinder REF signal is the latter half of the intake stroke and the initial compression stroke in the eighth cylinder. (Refer to FIG. 9). Therefore, it is preferable that the injection start timing of the eighth cylinder is as early as possible in the intake stroke, that is, close to the rising timing (t8) of the second cylinder REF signal. However, if it is too close to the rising timing (t8) of the REF signal for the second cylinder, the first cylinder and the injection start timing overlap, so in this embodiment, the injector is driven from the rising timing (t8) of the REF signal for the second cylinder. The timing (t41) at which the circuit charging time Tchg elapses is set as the injection start timing (intermediate timing) of the eighth cylinder. That is, the injection start timing of the eighth cylinder is the latter half of the intake stroke from FIG. Then, from the third cylinder, of course, the injection start timing is homogeneous combustion injection in the first half of the intake stroke.

  As a result, when the pre-ignition avoidance request flag is changed from 1 to zero before and after the five injection start timings from the second cylinder to the third cylinder are seen, the first half of the compression stroke (second cylinder) → Initial compression stroke (first cylinder) → Second half of intake stroke (8th cylinder) → Second half of intake stroke (7th cylinder) → First half of intake stroke (3rd cylinder) That is, in the case where there are two cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request for switching to homogeneous combustion is made, the situation shown in FIG. Both of the situations shown in FIG. 2B can be avoided, that is, simultaneous injection in two cylinders having different ignition orders (the first cylinder and the eighth cylinder in FIG. 6) can be avoided, and two timers are provided for injection control. You don't have to use it.

  The only problem here is that the injection start timing of the first cylinder is at the beginning of the compression stroke, that is, the timing at which 10 ° to 20 ° has elapsed from the compression stroke start timing. This is because the REF signal for No. 2 rises at a predetermined crank angle position in the initial stage of the compression stroke (that is, a timing at which 10 ° to 20 ° has elapsed from the compression stroke start timing) in the first cylinder. An appropriate injection start timing for obtaining stratified combustion is in the first half of the compression stroke. Therefore, if the injection start timing is at a timing when 10 ° to 20 ° has elapsed from the compression stroke start timing, the injection start timing is set as stratified combustion. Because it is too early, the combustion may become unstable and torque fluctuation may occur, and for homogeneous combustion, the spray start time is too late, so the atomization of the spray is poor and the combustion becomes unstable and torque fluctuation. May occur. However, as shown in FIG. 6, the injection in which the injection start timing is in the initial stage of the compression stroke is only one cylinder of the first cylinder, and the influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation Even if the degree is larger than a predetermined value (low rotational speed region), it is considered that there is not much influence on the torque fluctuation.

  On the other hand, FIG. 7 used when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is not more than a predetermined value will be described. In FIG. 7, the first cylinder and the eighth cylinder are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made. In this case, the first cylinder (the first cylinder in the ignition order among the two cylinders that have passed the injection start timing of the homogeneous combustion) is set as the REF signal synchronous injection. Further, the eighth cylinder (the second cylinder in the ignition order among the two cylinders that have passed the injection start timing of the homogeneous combustion) is set to the REF signal synchronous injection which is shifted in timing from the REF signal synchronous injection of the first cylinder. . That is, fuel injection is started at the rising timing (t8) of the reference REF signal (REF signal for the second cylinder) in the first cylinder and at the rising timing (t10) of the REF signal for the first cylinder in the eighth cylinder. At this time, the injection start timings of the first cylinder and the eighth cylinder are both in the initial stage of the compression stroke as shown in FIG. Then, from the seventh cylinder, of course, the homogeneous combustion injection having the injection start timing in the first half of the intake stroke is performed. In this case, in the seventh cylinder, the homogeneous combustion injection is performed at a timing t43 earlier in time than the timing t10 at which the injection of the eighth cylinder is performed. That is, the order of injection is reversed between the eighth cylinder and the seventh cylinder, and the seventh cylinder performs the injection earlier than the eighth cylinder.

  As a result, before and after the pre-ignition avoidance request flag is switched from 1 to zero, the five injection start timings from the second cylinder to the third cylinder are in the injection order (second cylinder → first cylinder → 7th cylinder → 8th cylinder). If you look at what happens in the cylinder → 3rd cylinder), the first half of the compression stroke (2nd cylinder) → the early stage of the compression stroke (1st cylinder) → the first half of the intake stroke (7th cylinder) → the first stage of the compression stroke (8th cylinder) → The first half of the intake stroke (3rd cylinder). That is, in the case where there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, the situation shown in FIG. Both of the situations shown in FIG. 2B can be avoided, that is, simultaneous injection in two cylinders (the first cylinder and the eighth cylinder) having different ignition orders can be avoided, and two timers are not used for injection control. I'm done.

  The problem here is that the injection start timings of the first cylinder and the eighth cylinder are both in the initial stage of the compression stroke, that is, the timing when 10 ° to 20 ° has elapsed from the compression stroke start timing. An appropriate injection start timing for obtaining stratified combustion is in the first half of the compression stroke. Therefore, if the injection start timing is at a timing when 10 ° to 20 ° has elapsed from the compression stroke start timing, the injection start timing is set as stratified combustion. Because it is too early, the combustion may become unstable and torque fluctuation may occur, and for homogeneous combustion, the spray start time is too late, so the atomization of the spray is poor and the combustion becomes unstable and torque fluctuation. May occur. However, as shown in FIG. 7, even if the injection in which the injection start timing is in the initial stage of the compression stroke occurs in the two cylinders of the first cylinder and the eighth cylinder, the homogeneity of the air-fuel mixture in the combustion chamber 8a becomes a torque fluctuation. If the degree of influence exerted is less than or equal to a predetermined value (high rotational speed range), it is considered that there is not much influence on torque fluctuation.

  Now, in FIG. 6, the third cylinder switches to homogeneous combustion injection, and in FIG. 7, the seventh cylinder switches to homogeneous combustion injection. When performing homogeneous combustion injection, a section from the rising timing of the REF signal for each cylinder to the homogeneous combustion injection start timing is preset in units of crank angle as a first predetermined crank angle section. The time required for the first predetermined crank angle section is affected by the engine speed Ne, and the higher the engine speed Ne, the shorter the time required for the first predetermined crank angle section. This means that in FIG. 6, the injection start timing of homogeneous combustion in the third cylinder approaches the REF signal synchronous injection of the seventh cylinder, so that the two cylinders of the seventh and third cylinders On the other hand, it is considered that the injection is performed at a timing close to each other, and the injection start timing overlaps in two cylinders. Further, in FIG. 7, it means that the injection start timing of the homogeneous combustion in the seventh cylinder approaches the REF signal synchronous injection of the first cylinder. Therefore, for the two cylinders of the first cylinder and the seventh cylinder, It is considered that the injection is performed at a close timing, and the injection start timing overlaps in two cylinders. Similarly, in FIG. 7, it means that the injection start timing of the homogeneous combustion in the third cylinder approaches the REF signal synchronous injection of the eighth cylinder. Therefore, for the two cylinders of the eighth and third cylinders, It is conceivable that the injection is performed at a timing close to each other, and the injection start timing overlaps in two cylinders. Then, due to a shortage of the charge amount of the injector drive circuit, in FIG. 6, fuel injection is caused by insufficient valve opening time in one of the two cylinders of the seventh cylinder and the third cylinder or in each of the injectors of the two cylinders. In FIG. 7, it is opened by either one of the two cylinders of the first cylinder and the seventh cylinder, or by one of the two cylinders of the eighth and third cylinders, or by the injector of each of the two cylinders. Due to insufficient valve time, the amount of fuel injection becomes insufficient, which may cause misfire, and the misfire may deteriorate drivability and exhaust emission.

  Therefore, in FIG. 6, the time required for the crank angle section from the rising timing (t10) of the first cylinder REF signal to the injection start timing of homogeneous combustion (calculated based on the engine rotational speed Ne) is a limiter (= injector drive circuit). The time required for the crank angle interval from the rising timing of the first cylinder REF signal to the injection start timing of homogeneous combustion is determined (= charge time Tchg of the injector drive circuit). The timing (t42) at which the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the first cylinder REF signal is set as the injection start timing of homogeneous combustion in the third cylinder. In contrast, when the time required for the crank angle interval from the rising timing of the REF signal for the first cylinder to the injection start timing of the homogeneous combustion is equal to or longer than the limiter (= charge time Tchg of the injector drive circuit), the first cylinder The timing at which the time required for the first predetermined crank angle section (the time corresponding to the first predetermined crank angle section) has elapsed from the rising timing of the REF signal for use is set as the homogeneous combustion injection start timing in the third cylinder.

  In FIG. 7, the time required for the crank angle section from the rising timing (t8) of the second cylinder REF signal to the start timing of homogeneous combustion (calculated based on the engine rotational speed Ne) is a limiter (= injector drive circuit). The time required for the crank angle section from the rising timing of the REF signal for the second cylinder to the injection start timing of homogeneous combustion is determined (= charge time Tchg of the injector drive circuit). The timing (t43) when the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal for the second cylinder is set as the injection start timing for homogeneous combustion in the seventh cylinder. On the other hand, when the time required for the crank angle section from the rising timing of the REF signal for the second cylinder to the injection start timing of the homogeneous combustion is equal to or longer than the limiter (= charge time Tchg of the injector drive circuit), the second cylinder The timing at which the time required for the first predetermined crank angle section (the time corresponding to the first predetermined crank angle section) has elapsed from the rising timing of the REF signal for use is set as the injection start timing of the homogeneous combustion in the seventh cylinder.

  Similarly, in FIG. 7, the time required for the crank angle section from the rising timing (t10) of the first cylinder REF signal to the start timing of homogeneous combustion (calculated based on the engine rotational speed Ne) is a limiter (= injector). The time required for the crank angle section from the rising timing of the REF signal for the first cylinder to the injection start timing of homogeneous combustion is determined by checking whether or not the charging time of the driving circuit is equal to or longer than the charging time Tchg). When it falls below (Tchg), the timing (t44) at which the charging time Tchg of the injector drive circuit elapses from the rising timing of the REF signal for the first cylinder is set as the injection start timing for homogeneous combustion in the third cylinder. In contrast, when the time required for the crank angle interval from the rising timing of the REF signal for the first cylinder to the injection start timing of the homogeneous combustion is equal to or longer than the limiter (= charge time Tchg of the injector drive circuit), the first cylinder The timing at which the time required for the first predetermined crank angle section (the time corresponding to the first predetermined crank angle section) has elapsed from the rising timing of the REF signal for use is set as the homogeneous combustion injection start timing in the third cylinder.

  Such control (control from FIG. 3 to FIG. 7) executed by the engine controller 15 will be described in detail with reference to the flowcharts of FIGS. 8A and 8B.

  8A and 8B are for setting the injection start timing of each cylinder. This flow is not repeatedly executed every fixed time, but shows a flow of control. The control is started from a state in which the pre-ignition avoidance request flag is 1 during engine operation. It should be noted that the engine may be started from a state in which the request flag is 1 for cold starting, not excluding when starting the engine. Here, in order to clarify the correspondence between each operation of the flow and FIGS. 3 to 7, a portion where the control of FIGS.

  In FIG. 8A, in step 1, it is determined whether or not there is a request for switching to homogeneous combustion, that is, whether or not the preignition avoidance request flag has been switched from 1 to zero. When the preignition avoidance request flag is switched from 1 to zero, the process proceeds to steps 2 and 3.

  In step 2, the first time, which is the time from the injection start timing of stratified combustion immediately before the request for switching to homogeneous combustion to the rise timing of the REF signal immediately after the request for switching to homogeneous combustion, and the injector The charging time Tchg of the drive circuit is the time from the rising timing of the REF signal immediately before the request for switching to homogeneous combustion in step 3 to the rising timing of the REF signal immediately after the timing of switching to homogeneous combustion. Is compared with the charging time Tchg × 2 of the injector driving circuit. Here, the first time and the second time are calculated based on the engine rotational speed Ne by a different routine, and the calculation results are used in FIGS. 8A and 8B.

  If the first time is equal to or shorter than the charging time Tchg of the injector driving circuit and the second time exceeds the charging time Tchg × 2 of the injector driving circuit as a result of the determination in Steps 2 and 3, go to Steps 4 and 5 move on. If the first time is equal to or shorter than the charging time Tchg of the injector driving circuit and the second time is equal to or shorter than the charging time Tchg × 2 of the injector driving circuit, the process proceeds to step 6. On the other hand, if the first time exceeds the charging time Tchg of the injector drive circuit, the process proceeds from step 2 to step 7.

  Steps 4 and 5 are parts for setting the injection start timings of the first and eighth cylinders shown in FIG. In step 4, the time from the rising timing of the REF signal immediately after the request for switching to homogeneous combustion to the injection start timing of the next cylinder (the first cylinder in FIG. 3) is the charging time Tchg of the injector drive circuit. The injection start time is set as the injection start time for the next cylinder. That is, the injection start timing of the next cylinder (the first cylinder in FIG. 3) is set to the timing at which the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal immediately after the timing at which switching to homogeneous combustion is requested. In step 5, the injection start timing of the REF signal synchronous injection is set as the injection start timing of the next cylinder (the eighth cylinder in FIG. 3). Thereafter, the process proceeds to step 9 and subsequent steps in FIG. 8B.

  Step 6 is a part for setting the injection start timing from the first cylinder shown in FIG. In step 6, the injection start timing of stratified combustion in the first half of the compression stroke is set as the injection start timing of the next cylinder (the first cylinder in FIG. 4), and the processing returns to steps 2 and 3. In step 2, the third time, which is the time from the start timing of stratified combustion injection to the input timing of the REF signal immediately after that, and the charging time Tchg of the injector drive circuit are set. In step 3, the input timing of the reference signal of 1 is set. Is compared with the charging time Tchg × 2 of the injector driving circuit. Here, the third time and the fourth time are calculated based on the engine rotational speed Ne after the timing when the request for switching to the homogeneous combustion is made, and the calculation results are shown in FIGS. 8A and 8B. Is used. For this reason, the third time is set to the injection start timing of the stratified charge combustion after the next next cylinder (cylinder 8 in FIG. 4) and the fourth time is less than the charging time Tchg of the injector drive circuit, and the fourth time is the injector drive circuit. If the third time exceeds the charging time Tchg of the injector driving circuit in step 2, the process proceeds to step 7. Alternatively, when the fourth time exceeds the charging time Tchg × 2 of the injector drive circuit in step 3 thereafter, the process proceeds to steps 4 and 5.

  Step 7 is a portion for setting the injection start timing from the first cylinder shown in FIG. In step 7, the injection start timing of the REF signal synchronous injection is set as the injection start timing of the next cylinder (the first cylinder in FIG. 5), and then in step 8, the second time exceeds the charging time Tchg × 2 of the injector drive circuit. See if they are. When the second time is equal to or shorter than the charging time Tchg × 2 of the injector drive circuit, the process returns to step 7 and the injection start timing of the next cylinder (the eighth cylinder in FIG. 5) is set as the injection start timing of the REF signal synchronous injection. Then, go to Step 8. In step 8, the fourth time is compared with the charging time Tchg × 2 of the injector driving circuit. As long as the fourth time is the charging time Tchg × 2 of the injector drive circuit, the process returns to step 7 and continues to set the injection start timing of the REF signal synchronous injection as the injection start timing for the next and subsequent cylinders. Eventually, when the fourth time exceeds the charging time Tchg × 2 of the injector driving circuit in step 8, the process proceeds from step 8 to step 9 and subsequent steps in FIG. 8B.

  In FIG. 8B, in step 9, the engine speed Ne is compared with a threshold value. The threshold value is a value that divides the high rotation speed region and the other regions and is determined in advance. When the engine rotational speed Ne is smaller than the threshold value, that is, in the low rotational speed region, it is determined that the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is greater than a predetermined value, and after step 10 move on. On the other hand, when the engine rotational speed Ne is equal to or higher than the threshold value, that is, in the high rotational speed range, it is determined that the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is equal to or less than a predetermined value. Proceed to the following. Here, the predetermined value is the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation under the condition that the engine rotational speed Ne matches the threshold value.

  Steps 10, 11, 12, 13, and 19 are parts for setting the injection start timing from the eighth cylinder shown in FIG. In step 10, the time from the rising timing of the REF signal immediately after the request for switching to homogeneous combustion to the injection start timing of the next cylinder (the eighth cylinder in FIG. 6) is the charging time Tchg of the injector drive circuit. The injection start time is set as the injection start time for the next cylinder. That is, the injection start timing of the next cylinder (cylinder No. 8 in FIG. 6) is set to the timing at which the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal immediately after the timing at which switching to homogeneous combustion is requested. In step 11, the injection start timing of the REF signal synchronous injection is set as the injection start timing of the next cylinder (the seventh cylinder in FIG. 6).

  Here, the operation in step 10 corresponds to setting an intermediate injection start timing for the eighth cylinder, and the operation in step 11 corresponds to setting REF signal synchronous injection for the seventh cylinder. Accordingly, in FIG. 6B, the operation in which the REF signal synchronous injection is performed with respect to the first cylinder immediately before the 8th cylinder in the ignition order in FIG. However, if the first time exceeds the charging time Tchg of the injector driving circuit and the second time exceeds the charging time Tchg × 2 of the injector driving circuit at the timing when the request for switching to homogeneous combustion is made, FIG. 8A steps 2, 7, and 8 and steps 9, 10, and 11 in FIG. 8B, the REF signal synchronous injection is performed for the first cylinder in the ignition order one before the eighth cylinder in FIG. The operation is performed in Step 7 of FIG. 8A. Alternatively, if the first time exceeds the charging time Tchg of the injector driving circuit and then the fourth time exceeds the charging time Tchg × 2 of the injector driving circuit, step 2 in FIG. 7, 7, 7, 8, steps 9, 10, and 11 in FIG. 8B, the REF signal synchronous injection is performed for the first cylinder in the ignition order one before the eighth cylinder in FIG. 6. The operation is performed in Step 7 of FIG. 8A.

  On the other hand, when steps 2, 3, 4, 5 in FIG. 8A and steps 9, 10, 11 in FIG. 8B proceed, “the time from the REF signal rising timing to the injection start timing is the charging time of the injector drive circuit. In this case, the injection start timing is set to "REF signal synchronous injection" → "intermediate injection start timing is set" → "REF signal synchronous injection". There is a shortage of operations for REF signal synchronous injection to the cylinder. However, when shifting from the connection control in FIG. 3 to the main control in FIG. 6, FIG. 3 and FIG. 6 are combined as they are, and “the time from the REF signal rising timing to the injection start timing is set as the charging time of the injector drive circuit. Instead of “setting of injection start timing” → “REF signal synchronous injection” followed by “REF signal synchronous injection” → “intermediate injection start timing setting” → “REF signal synchronous injection”, the first “ The “REF signal synchronous injection” is omitted, and after FIG. 3, “intermediate injection start timing setting” in FIG. 6 is taken over. In this way, by switching from the linkage control shown in FIG. 3 to the main control shown in FIG. 6, one switching of the stratified combustion injection to the homogeneous combustion injection is completed earlier by omitting one REF signal synchronous injection. Can be made.

  Steps 12 and 13 are parts for preventing the fuel injection amount from being insufficient at the time of injection of homogeneous combustion in the first cylinder after switching to homogeneous combustion, that is, the third cylinder in FIG. In step 12, the time required for the crank angle section from the rising timing of the REF signal used for the REF signal synchronous injection in step 11 to the injection start timing of homogeneous combustion (calculated based on the engine speed Ne) is a limiter (= injector drive). The time required for the crank angle section from the rising timing of the REF signal used for the REF signal synchronous injection in step 11 to the injection start timing of homogeneous combustion is determined by checking whether or not the circuit charging time Tchg) is longer than the limiter (= injector) If the charging time Tchg of the injector driving circuit has elapsed from the rising timing of the REF signal used for the synchronous injection of the REF signal in step 11 in step 13 when the charging time Tchg of the driving circuit is below, the next cylinder ( Injection start of cylinder No. 3 in FIG. After you set as the period, and sets the injection start timing of the homogeneous combustion to the next next next next cylinder proceeds to step 17 (FIG. 6, 6 cylinder). On the other hand, the time required for the crank angle section from the rising timing of the REF signal used for the REF signal synchronous injection in step 11 to the injection start timing of homogeneous combustion in step 12 (= charge time Tchg of the injector drive circuit) If it is above, the process proceeds to step 19 as it is, and the injection start timing of homogeneous combustion is set in the next next cylinder.

  Having reached Step 19 means that the injection has been switched to the homogeneous combustion injection, and thereafter, the injection start timing of the homogeneous combustion is set in all the cylinders.

  On the other hand, steps 14, 15, 16, 17, and 19 are parts for setting the injection start timing from the eighth cylinder shown in FIG. In step 14, the injection start timing of the REF signal synchronous injection is set as the injection start timing of the next cylinder (8th cylinder in FIG. 7).

  Here, since the operation in step 14 corresponds to the setting of the REF signal synchronous injection for the eighth cylinder, in FIG. 7, the first cylinder in the ignition order one before the eighth cylinder in FIG. Thus, the operation of the REF signal synchronous injection is not found in FIG. 8B. However, if the first time exceeds the charging time Tchg of the injector driving circuit and the second time exceeds the charging time Tchg × 2 of the injector driving circuit at the timing when the request for switching to homogeneous combustion is made, FIG. 8A steps 2, 7, and 8 and steps 9 and 14 in FIG. 8B, the operation in which the REF signal synchronous injection is performed for the first cylinder in the ignition order one before the eighth cylinder in FIG. This is performed in step 7 of FIG. 8A. Alternatively, if the first time exceeds the charging time Tchg of the injector driving circuit and then the fourth time exceeds the charging time Tchg × 2 of the injector driving circuit, step 2 in FIG. 7, 7, 7, 8, and steps 9 and 14 in FIG. 8B, the operation in which the REF signal synchronous injection is performed for the first cylinder in the ignition order one before the eighth cylinder in FIG. This is performed in step 7 of FIG. 8A.

  On the other hand, when steps 2, 3, 4, 5 in FIG. 8A and steps 9, 14, 15 and 18 in FIG. 8B proceed, “the time from the rise timing of the REF signal to the injection start timing is determined by the injector drive circuit. “Setting of injection start timing as charging time” → “REF signal synchronous injection” → “REF signal synchronous injection” → “setting of homogeneous combustion injection start timing” In FIG. The operation for the REF signal synchronous injection is insufficient with respect to the previous first cylinder. However, when shifting from the connection control of FIG. 3 to the main control of FIG. 7, FIG. 3 and FIG. Instead of “setting of injection start timing” → “REF signal synchronous injection” followed by “REF signal synchronous injection” → “REF signal synchronous injection” → “setting of injection start timing of homogeneous combustion” The “REF signal synchronous injection” is omitted, and after FIG. 3, the second “REF signal synchronous injection” of FIG. 7 is taken over. As described above, when switching from the linkage control shown in FIG. 3 to the main control shown in FIG. 7, one REF signal synchronous injection is omitted, so that the switching from the stratified combustion injection to the homogeneous combustion injection is completed earlier. Can be made.

  The operations in steps 15, 16, and 17 are the same as the operations in steps 12 and 13. That is, the time required for the crank angle section from the rising timing of the REF signal used for the REF signal synchronous injection in step 5 or step 7 to the injection start timing of homogeneous combustion in step 15 (= charge time Tchg of the injector drive circuit) If the time required for the crank angle interval from the rising timing of the REF signal to the injection start timing of homogeneous combustion is less than the limiter (= charge time Tchg of the injector drive circuit), it is determined in step 16 whether or not it is above. Alternatively, the timing at which the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal used for the REF signal synchronous injection in step 7 is set as the injection start timing of the next cylinder (the seventh cylinder in FIG. 7). Continue with step 17 to step 5 or The injection of the next cylinder (the third cylinder in FIG. 7) follows the timing when the charging time Tchg of the injector driving circuit has elapsed from the rising timing of the REF signal next to the REF signal used for the REF signal synchronous injection in Step 7. After setting as the start time, the routine proceeds to step 19, where the injection start time of homogeneous combustion is set to the next next cylinder (the sixth cylinder in FIG. 7). On the other hand, the time required for the crank angle section from the rising timing of the REF signal used for the REF signal synchronous injection in step 5 or step 7 to the injection start timing of homogeneous combustion in step 15 (= charge of the injector drive circuit) If the time is equal to or greater than the time Tchg), the routine proceeds to step 18 and sets the homogeneous combustion injection start timing in the next next cylinder, and then proceeds to step 19 and sets the homogeneous combustion injection start timing to the next next cylinder. set.

  Having reached Step 19 means that the injection has been switched to the homogeneous combustion injection, and thereafter, the injection start timing of the homogeneous combustion is set in all the cylinders.

  Here, the effect of this embodiment is demonstrated.

  According to the present embodiment (the invention described in claim 2), the injector 13 capable of directly injecting fuel into the combustion chamber 8a for each cylinder and the REF signal generated at a predetermined crank angle position for each cylinder are provided. After the elapse of the first predetermined crank angle interval from the rising timing (input timing) of the REF signal for each cylinder, the injection start timing of homogeneous combustion is greater than the first predetermined crank angle interval from the input timing of the reference REF signal for each cylinder. After the passage of the large second predetermined crank angle interval, the start timing of the stratified combustion is set in advance, and the switching from the homogeneous combustion injection to the stratified combustion injection is performed at the timing when the switching request to the stratified combustion is requested. In a fuel injection control device for a direct-injection spark-ignition engine that switches from stratified combustion injection to homogeneous combustion injection at the timing when there is a request for switching When there are two cylinders that have passed the homogenous combustion injection start timing at the timing of the request for switching to homogeneous combustion (t7 in FIG. 6), the two cylinders that have passed the homogeneous combustion injection start timing Among them, the rising timing of the REF signal (the REF signal for the second cylinder in FIG. 6) immediately after the timing when the injection start timing of the first cylinder in the ignition order (the first cylinder in FIG. 6) is requested to switch to homogeneous combustion ( REF signal synchronous injection set to (input timing) (see step 7 in FIG. 8A), and the injection start timing of the cylinder after the two cylinders (7th cylinder in FIG. 6) that has passed the injection start timing of homogeneous combustion is set. REF signal synchronous injection set at the rising timing of the REF signal (the REF signal for the first cylinder in FIG. 6) next to the REF signal immediately after the request for switching to homogeneous combustion is made (FIG. 8B). Step 11), the injection start timing of the second cylinder in the firing order (8th cylinder in FIG. 6) of the two cylinders that have passed the injection start timing of homogeneous combustion is indicated by the first cylinder (in FIG. 6). Since the injection start time of the first cylinder) and the injection start time of the next cylinder (the seventh cylinder in FIG. 6) of the two cylinders are set (see step 10 of FIG. 8B), the ignition sequence Since it is possible to secure the voltage boost time of the injector drive circuit while preventing simultaneous injection in a plurality of cylinders having different cylinders (the first cylinder and the eighth cylinder in FIGS. 6 and 7), the timing at which switching to homogeneous combustion is requested Even when there are two or more cylinders that have passed the injection start timing of homogeneous combustion, it is possible to reduce the variation in fuel injection amount due to insufficient injector drive current, and operation when switching from stratified combustion to homogeneous combustion Sexual I can go up.

  Further, in order to perform fuel injection at the intermediate timing, that is, to perform injection other than the reference signal synchronous injection, it is necessary to start a timer from the input timing of the reference signal. According to the invention described in Item 2, since only one timer is required to be started at the rising timing of the REF signal, the calculation load is not deteriorated.

  According to the present embodiment (the invention described in claim 15), the injector 13 capable of directly injecting fuel into the combustion chamber 8a for each cylinder and the REF signal generated at a predetermined crank angle position for each cylinder are provided. After the elapse of the first predetermined crank angle interval from the rising timing (input timing) of the REF signal for each cylinder, the injection start timing of homogeneous combustion is greater than the first predetermined crank angle interval from the input timing of the reference REF signal for each cylinder. After the passage of the large second predetermined crank angle interval, the start timing of the stratified combustion is set in advance, and the switching from the homogeneous combustion injection to the stratified combustion injection is performed at the timing when the switching request to the stratified combustion is requested. In a fuel injection control system for a direct-injection spark ignition engine that switches from stratified charge injection to homogeneous combustion injection The effect of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation when there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when there is a request to switch to homogeneous combustion (t7 in FIG. 6) When the degree is larger than a predetermined value, a request to switch the injection start timing of the first cylinder (the first cylinder in FIG. 6) in the ignition order to homogeneous combustion among the two cylinders that have passed the injection start timing of homogeneous combustion REF signal synchronous injection set at the rising timing (input timing) of the REF signal (the REF signal for the second cylinder in FIG. 6) immediately after the timing of occurrence (see step 7 of FIG. 8A), and the injection start timing of homogeneous combustion is set The REF signal next to the REF signal immediately after the request to switch the injection start timing of the next cylinder after the two cylinders (7th cylinder in FIG. 6) to the homogeneous combustion to the 1st in FIG. REF signal synchronous injection set at the rise timing of the REF signal (see step 11 in FIG. 8B), and the second cylinder in the firing order (in FIG. 6, out of the two cylinders that have passed the injection start timing of homogeneous combustion) Injection start timing of the first cylinder (the first cylinder in FIG. 6), and the injection start timing of the next cylinder after the two cylinders (the seventh cylinder in FIG. 6). (See step 10 in FIG. 8B), and when there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the switching to the homogeneous combustion is requested, and the mixture in the combustion chamber Of the first cylinder in the firing order (the first cylinder in FIG. 6) of the two cylinders that have passed the injection start timing of the homogeneous combustion when the degree of influence of the homogeneity on the torque fluctuation is equal to or less than a predetermined value. Homogeneous injection start time The REF signal synchronous injection is set to the rising timing of the REF signal (the REF signal for the second cylinder in FIG. 6) immediately after the timing when the switching to combustion is requested (see step 7 in FIG. 8A), and the injection start timing of homogeneous combustion The REF signal next to the REF signal immediately after the timing at which the injection start timing of the second cylinder (8th cylinder in FIG. 6) in the ignition order among the two cylinders that have passed is requested to switch to homogeneous combustion is shown (FIG. 6). 6 is the REF signal synchronous injection set at the input timing of the first cylinder REF signal (see step 14 in FIG. 8B), so that a plurality of cylinders having different ignition orders (in FIG. 6 and FIG. (Cylinder No. Cylinder) can prevent the simultaneous injection in the injector drive circuit while ensuring the voltage boost time of the injector drive circuit, the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than the predetermined value. There are two cylinders that have passed the start timing of homogeneous combustion when there is a request to switch to homogeneous combustion, and the degree of influence of the homogeneity of the mixture in the combustion chamber on the torque fluctuation. Insufficient injector drive current regardless of whether there are two cylinders that are less than the predetermined value and there are two cylinders that have passed the injection start timing of homogeneous combustion at the timing when a request for switching to homogeneous combustion has occurred This makes it possible to reduce the variation in the fuel injection amount due to the engine, improve the operability when switching from stratified combustion to homogeneous combustion, and the degree of influence of the homogeneity of the mixture in the combustion chamber on the torque fluctuation is less than the predetermined value. In some cases, when there are two cylinders that have passed the injection start timing of homogeneous combustion at the timing when a request for switching to homogeneous combustion is made, the homogeneous combustion is started at an earlier timing. It is possible to perform the switching to the injection.

  In order to perform fuel injection at the intermediate timing, that is, to perform injection other than REF signal synchronous injection, it is necessary to start a timer from the rising timing of the REF signal. According to (15), since only one timer is required to be started at the rising timing of the REF signal, the calculation load of the engine controller 15 is not deteriorated.

  Since the first time and the second time vary depending on the engine speed Ne, depending on the first time and the second time, the REF signal synchronous injection becomes impossible or the intermediate timing cannot be set. Sometimes. In order to cope with this, according to the present embodiment (the invention described in claim 3), at the timing (t7) when the switching request to the homogeneous combustion is requested, the injection start timing of the stratified combustion immediately before this timing is changed to the homogeneous combustion. The first time that is the time until the rising timing of the REF signal (the REF signal for the second cylinder) immediately after the timing when the switching request is made, and the REF signal (the fourth cylinder) immediately before the timing when the switching request to the homogeneous combustion is requested Based on the engine speed Ne, the second time, which is the time from the rise timing of the REF signal for REF) to the rise timing of the REF signal (the REF signal for the second cylinder) immediately after the request for switching to homogeneous combustion, is made. Calculate and determine whether or not REF signal synchronous injection is possible based on the first time (see step 2 of FIG. 8A), and intermediate based on the second time Since it is determined whether or not the timing can be set (see steps 3 and 8 in FIG. 8A), the REF signal synchronous injection is impossible, but the REF signal synchronous injection or the intermediate timing cannot be set. However, it is possible to avoid setting an intermediate period.

  According to the present embodiment (the invention described in claim 4), it is determined whether or not the REF signal synchronous injection based on the first time is possible by comparing the first time and the charging time of the injector driving circuit (FIG. 8A). Step 2 of FIG. 8), it is determined whether the intermediate time can be set based on the second time by comparing the second time with twice the charging time of the injector drive circuit (see Steps 3 and 8 in FIG. 8A). Therefore, it is possible to accurately determine whether or not the REF signal synchronous injection is possible and whether or not the intermediate timing can be set.

  According to the present embodiment (the invention described in claim 6), the REF signal (the REF signal for the second cylinder) immediately after the injection start timing of the stratified combustion after the timing (t7) when the request for switching to the homogeneous combustion is made. ) A time calculating means for calculating a third time which is a time until the rise (input timing) of the first REF signal and a fourth time which is a time from the rise (input timing) of one REF signal to the rise timing of the next REF signal. If the first time is less than or equal to the charging time of the injector drive circuit and the second time is less than or equal to twice the charge time of the injector drive circuit, the third time exceeds the charging time of the injector drive circuit Alternatively, the stratified combustion injection is performed in each cylinder immediately after the timing at which switching to homogeneous combustion is requested until the fourth time exceeds twice the charging time of the injector drive circuit. (See steps 2, 3, and 6 in FIG. 8A), the first time is less than or equal to the charging time of the injector drive circuit, and the second time is less than or equal to twice the charge time of the injector drive circuit. However, after the timing (t7) when the switching request to the homogeneous combustion is requested, it is possible to appropriately switch to the homogeneous combustion injection while securing the voltage boosting time of the injector drive circuit.

  According to the present embodiment (the invention described in claim 7), from the rising timing (input timing) of one REF signal after the timing (t7) when the switching request to the homogeneous combustion is requested, the rising timing of the next REF signal. A time calculating means for calculating a fourth time, which is a time of the first time, the first time exceeds the charging time of the injector driving circuit, and the second time is not more than twice the charging time of the injector driving circuit. The fuel injection start timing for each cylinder immediately after the timing when switching to homogeneous combustion is requested until the fourth time exceeds twice the charging time of the injector drive circuit, immediately after the timing when switching to homogeneous combustion is requested Since the REF signal synchronous injection set at the rising timing of the REF signal from the REF signal continues (see steps 2, 7, 8, and 7 in FIG. 8A), the first time is Even when the charging time of the injector driving circuit is exceeded and the second time is not more than twice the charging time of the injector driving circuit, after the timing (t7) when the switching request to the homogeneous combustion is requested, It is possible to appropriately switch to the homogeneous combustion injection while ensuring the voltage boosting time.

  According to the present embodiment (the invention described in claim 8), the injector is started from the rising timing of the REF signal (the REF signal for the second cylinder in FIG. 6) immediately after the request for switching to homogeneous combustion is made as an intermediate timing. Since the timing at which the charging time of the drive circuit elapses is set (see step 10 in FIG. 8B), the second cylinder in the firing order among the two cylinders that have passed the injection start timing of homogeneous combustion (# 8 in FIG. 6) Cylinder) injection start timing can be made closest to the rising timing of the REF signal (the REF signal for the second cylinder in FIG. 6) immediately after the request for switching to homogeneous combustion while ensuring the charging time, Sufficient time can be secured for vaporization of the fuel spray.

  According to this embodiment (the invention described in claim 12), in the homogeneous combustion injection of the next cylinder (the third cylinder in FIG. 6) next to the two cylinders that have passed the homogeneous combustion injection start timing, Next to the two cylinders that have passed the injection start timing of the homogeneous combustion from the rising timing of the REF signal (the REF signal for the first cylinder in FIG. 6) immediately after the timing when the switching request to the homogeneous combustion is requested. When the time until the injection start timing of the homogeneous combustion of the next cylinder (the third cylinder in FIG. 6) is shorter than the charging time of the injector drive circuit, the next of the two cylinders that have passed the injection start timing of the homogeneous combustion. The injection start timing of the homogeneous combustion of the cylinder (No. 3 cylinder in FIG. 6) is the REF signal (REF signal for the first cylinder in FIG. 6) next to the REF signal immediately after the request for switching to the homogeneous combustion. Rise timing Since the charging time of the injector drive circuit has elapsed (see steps 12 and 13 in FIG. 8B), the next cylinder after the two cylinders that have passed the injection start timing of homogeneous combustion (number 3 in FIG. 6). Since the voltage increase time of the injector drive circuit can be secured even during the homogeneous combustion injection of the cylinder), variation in the fuel injection amount due to insufficient injector drive current can be reduced, and the operability when switching from stratified combustion to homogeneous combustion is improved. .

  According to the present embodiment (the invention described in claim 16), when there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the mixture in the combustion chamber When the degree of influence of the homogeneity on the torque fluctuation is equal to or less than a predetermined value, in the homogeneous combustion injection of the next cylinder after the injection start timing of the homogeneous combustion (the seventh cylinder in FIG. 7), The next cylinder after the two cylinders (in FIG. 7, the injection start timing of the homogeneous combustion has passed from the rising timing of the REF signal (the REF signal for the second cylinder in FIG. 7) immediately after the timing when the request for switching to the homogeneous combustion is made. When the time until the injection start timing of homogeneous combustion is shorter than the charging time of the injector drive circuit, the next cylinder after the two cylinders that have passed the injection start timing of homogeneous combustion (the seventh cylinder in FIG. 7) ) Homogeneity The firing injection start timing is set to the timing at which the charging time of the injector drive circuit has elapsed from the rising timing of the REF signal (the REF signal for the second cylinder in FIG. 7) immediately after the timing at which the switch to homogeneous combustion is requested ( (Refer to steps 15 and 16 in FIG. 8B.) When there are two cylinders that have passed the injection start timing of homogeneous combustion at the timing when a request for switching to homogeneous combustion has occurred, and the homogeneity of the air-fuel mixture in the combustion chamber becomes a torque fluctuation. When the influence degree is less than or equal to a predetermined value, the voltage of the injector drive circuit is also used in the homogeneous combustion injection of the next cylinder after the homogeneous combustion injection start timing (the seventh cylinder in FIG. 7). Since the boosting time can be secured, variation in fuel injection amount due to insufficient injector drive current can be reduced, improving operability when switching from stratified combustion to homogeneous combustion That.

  According to this embodiment (the invention described in claim 17), when there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the mixture in the combustion chamber When the degree of influence of the homogeneity on the torque fluctuation is a predetermined value or less, the homogeneous combustion injection of the next cylinder (the third cylinder in FIG. 7) next to the two cylinders that have passed the homogeneous combustion injection start timing In this case, the two cylinders that have passed the injection start timing of the homogeneous combustion after the rising timing of the REF signal (the REF signal for the first cylinder in FIG. 7) immediately after the timing of the request for switching to the homogeneous combustion. When the time until the injection start timing of the homogeneous combustion of the next next cylinder (the third cylinder in FIG. 7) is shorter than the charging time of the injector drive circuit, the next of the two cylinders that have passed the injection start timing of the homogeneous combustion Next mind The injection start timing of the homogeneous combustion of (the third cylinder in FIG. 7) is the rising timing of the REF signal (the REF signal for the first cylinder in FIG. 7) immediately after the timing when the request for switching to the homogeneous combustion is made. Since the timing when the charging time of the injector drive circuit has elapsed from the start (see steps 15 and 17 in FIG. 8B), there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made. In some cases and when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is equal to or less than a predetermined value, the next cylinder after the two cylinders that have passed the injection start timing of the homogeneous combustion (in FIG. 7) (3rd cylinder) homogeneous combustion injection can also ensure the voltage boost time of the injector drive circuit, reducing the variation in fuel injection amount due to insufficient injector drive current. , Thereby improving operability at the time of switching to the homogeneous combustion from the stratified combustion.

  Next, FIG. 10 and FIG. 11 are 2nd Embodiment and replace FIG. 6, FIG. 7 of 1st Embodiment. That is, when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is larger than a predetermined value, FIG. FIG. 11 is adopted in the following cases.

  The second embodiment deals with a case where three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made.

  The description will be made with reference to FIG. In FIG. 10, the first cylinder, the eighth cylinder, and the seventh cylinder are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing (t7 ') when the request for switching to the homogeneous combustion is made. In this case, the first cylinder (the first cylinder in the ignition order among the three cylinders past the homogeneous combustion injection start timing) and the seventh cylinder (the three cylinders past the homogeneous combustion injection start timing). Among them, the third cylinder in the ignition order) is assumed to be REF signal synchronous injection with a shifted timing. Further, the sixth cylinder (the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing) has passed the homogeneous combustion injection start timing at the timing (t7 ') when a request for switching to homogeneous combustion has been made. Although the cylinder is not a cylinder, the REF signal synchronous injection of the 6th cylinder is shifted in timing from the REF signal synchronous injection of the 1st and 7th cylinders. That is, the rising timing (t10) of the REF signal for the first cylinder in the first cylinder, the rising timing (t12) of the REF signal for the eighth cylinder in the seventh cylinder, and the rising timing of the REF signal for the seventh cylinder in the sixth cylinder. Fuel injection is started at timing (t14). At this time, the injection start timing of the first cylinder is the latter half of the compression stroke from FIG. 9, the injection start timing of the seventh cylinder is the initial compression stroke from FIG. 9, and the injection start timing of the sixth cylinder is the second half of the intake stroke from FIG. Become.

  On the other hand, the injection start timing of the eighth cylinder (the second cylinder in the ignition order among the three cylinders that have passed the injection start timing of homogeneous combustion) is the injection start timing of the first cylinder and the injection start of the seventh cylinder. Set the time in the middle of the time. That is, in the eighth cylinder, fuel injection is started at an intermediate timing between the timing of t10 and the timing of t12. Here, “intermediate timing” does not mean only the middle timing between the timing of t10 and the timing of t12. Theoretically, as long as it is between the timing of t10 and the timing of t12, it may be close to t10 or vice versa. Actually, the crank angle section between the rising timing (t10) of the first cylinder REF signal and the rising timing (t12) of the eighth cylinder REF signal corresponds to the first half of the compression stroke in the eighth cylinder. (See FIG. 9). If it is too close to the rising timing (t10) of the first cylinder REF signal, the first cylinder and the injection start timing overlap, so in the second embodiment, the injector drive circuit starts from the rising timing (t10) of the eighth cylinder REF signal. The timing (t51) when the charging time Tchg elapses is set as the injection start timing (intermediate timing) of the eighth cylinder. That is, the injection start timing of the eighth cylinder is the first half of the compression stroke from FIG.

  Also, the injection start timing of the third cylinder (the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing) is set to an intermediate between the injection start timing of the seventh cylinder and the injection start timing of the sixth cylinder. Set to the time. That is, in the third cylinder, fuel injection is started at an intermediate timing between the timing t12 and the timing t14. Here, “intermediate timing” does not mean only the middle timing between the timing of t12 and the timing of t14. Theoretically, as long as it is between the timing of t12 and the timing of t14, it may be close to t12 or vice versa. Actually, the crank angle interval between the rising timing (t12) of the eighth cylinder REF signal and the rising timing (t14) of the seventh cylinder REF signal is the latter half of the intake stroke and the initial compression stroke in the third cylinder. (Refer to FIG. 9). Therefore, it is preferable that the injection start timing of the third cylinder is as early as possible in the intake stroke, that is, close to the rising timing (t12) of the eighth cylinder REF signal. However, if it is too close to the rising timing (t12) of the eighth cylinder REF signal, the injection start timing overlaps with the seventh cylinder. Therefore, in the second embodiment, the injector is started from the rising timing (t12) of the eighth cylinder REF signal. The timing (t52) at which the charging time Tchg of the drive circuit elapses is set as the injection start timing (intermediate timing) of the third cylinder. That is, the injection start timing of the third cylinder is the latter half of the intake stroke from FIG. Then, from the fifth cylinder, of course, the homogeneous combustion injection having the injection start timing in the first half of the intake stroke is performed.

  As a result, the first half of the compression stroke (2nd cylinder) is shown by looking at the 7 injection start timings from the 2nd cylinder to the 5th cylinder before and after switching the preignition avoidance request flag from 1 to zero. → The second half of the compression stroke (Cylinder 1) → The first half of the compression stroke (Cylinder 8) → The initial compression stroke (Cylinder 7) → The second half of the intake stroke (Cylinder 3) → The second half of the intake stroke (Cylinder 6) → The first half of the intake stroke ( No. 5 cylinder). That is, in the case where there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, the configuration shown in FIG. Simultaneous injection in the first cylinder, the eighth cylinder, and the seventh cylinder in FIG. 10 can be avoided, and it is not necessary to use two or more timers for injection control.

  The only problem here is that the injection start timing of the seventh cylinder is at the beginning of the compression stroke, that is, the timing at which 10 ° to 20 ° has elapsed from the compression stroke start timing, as described above with reference to FIG. An appropriate injection start timing for obtaining stratified combustion is in the first half of the compression stroke. Therefore, if the injection start timing is at a timing when 10 ° to 20 ° has elapsed from the compression stroke start timing, the injection start timing is set as stratified combustion. Because it is too early, the combustion may become unstable and torque fluctuation may occur, and for homogeneous combustion, the spray start time is too late, so the atomization of the spray is poor and the combustion becomes unstable and torque fluctuation. May occur. However, as shown in FIG. 10, the injection in which the injection start timing is in the initial stage of the compression stroke is only one cylinder of the seventh cylinder, and the influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation Even if the degree is larger than a predetermined value (low rotational speed region), it is considered that there is not much influence on the torque fluctuation.

  On the other hand, FIG. 11 used when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber 8a on the torque fluctuation is not more than a predetermined value will be described. In FIG. 11, the first cylinder, the eighth cylinder, and the seventh cylinder are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the switching request to the homogeneous combustion is requested. In this case, the first cylinder (the first cylinder in the firing order among the three cylinders past the homogeneous combustion injection start timing) is set as the REF signal synchronous injection. In addition, the eighth cylinder (the second cylinder in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion) is set to the REF signal synchronous injection whose timing is different from the REF signal synchronous injection of the first cylinder. . Further, the seventh cylinder (the third cylinder in the firing order among the three cylinders that have passed the injection start timing of the homogeneous combustion) is synchronized with the REF signal synchronized with the REF signal synchronous injection of the first cylinder and the eighth cylinder. Let it be a jet. That is, the rising timing of the REF signal for the first cylinder in the first cylinder (t10), the rising timing of the REF signal for the eighth cylinder in the eighth cylinder (t12), and the rising of the REF signal for the seventh cylinder in the seventh cylinder Fuel injection is started at timing (t14). At this time, the injection start timings of the first cylinder, the eighth cylinder, and the seventh cylinder are all in the first half of the compression stroke as shown in FIG. Then, from the third cylinder, of course, the homogeneous combustion injection having the injection start timing in the first half of the intake stroke is performed. In this case, in the third cylinder, homogeneous combustion injection is performed at a timing t11 earlier in time than the timing t12 at which the injection of the eighth cylinder is performed. That is, the injection order is reversed between the eighth cylinder and the third cylinder, and the third cylinder performs the injection earlier than the eighth cylinder. Similarly, in the sixth cylinder, the homogeneous combustion injection is performed at a timing t13 earlier in time than the timing t14 at which the seventh cylinder injection is performed. That is, the injection order is reversed between the seventh cylinder and the sixth cylinder, and the sixth cylinder performs the injection earlier than the seventh cylinder.

  As a result, before and after the pre-ignition avoidance request flag is switched from 1 to zero, the six injection start timings from the second cylinder to the sixth cylinder are in the order of injection (second cylinder → first cylinder → third cylinder → 8th cylinder). The first half of the compression stroke (second cylinder) → first half of the compression stroke (first cylinder) → the first half of the intake stroke (third cylinder) → the first half of the compression stroke (8th cylinder) → first half of intake stroke (6th cylinder) → first half of compression stroke (7th cylinder) That is, in contrast to the case where there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, the three cylinders having different ignition orders can also be configured as shown in FIG. Simultaneous injection in the first cylinder, the eighth cylinder, and the seventh cylinder in FIG. 11 can be avoided, and it is not necessary to use two or more timers for injection control.

  Note that unlike FIG. 7 of the first embodiment, FIG. 11 does not have a cylinder in which the injection start timing is in the initial stage of the compression stroke.

  Now, in FIG. 10, the combustion is switched to homogeneous combustion in the fifth cylinder, and in FIG. 11, the injection is switched to homogeneous combustion in the third and sixth cylinders. When performing homogeneous combustion injection, a section from the rising timing of the REF signal for each cylinder to the homogeneous combustion injection start timing is preset in units of crank angle as a first predetermined crank angle section. The time required for the first predetermined crank angle section is affected by the engine speed Ne, and the higher the engine speed Ne, the shorter the time required for the first predetermined crank angle section. This means that in FIG. 10, the injection start timing of homogeneous combustion in the No. 5 cylinder approaches the REF signal synchronous injection of the No. 6 cylinder, so that there are two cylinders, the No. 6 cylinder and the No. 5 cylinder. On the other hand, it is considered that the injection is performed at a timing close to each other, and the injection start timing overlaps in two cylinders. Further, in FIG. 11, it means that the injection start timing of the homogeneous combustion in the third cylinder approaches the REF signal synchronous injection of the first cylinder, so for the two cylinders of the first and third cylinders It is considered that the injection is performed at a close timing, and the injection start timing overlaps in two cylinders. Similarly, in FIG. 11, it means that the injection start timing of the homogeneous combustion in the sixth cylinder approaches the REF signal synchronous injection of the eighth cylinder. Therefore, for the two cylinders of the eighth and sixth cylinders, It is conceivable that the injection is performed at a timing close to each other, and the injection start timing overlaps in two cylinders. Then, due to a shortage of the charge amount of the injector drive circuit, in FIG. 10, fuel injection occurs due to insufficient valve opening time in one of the two cylinders of the sixth and fifth cylinders or in each of the two cylinders. In FIG. 11, it is opened by either one of the two cylinders of the first cylinder and the third cylinder, or by one of the two cylinders of the eighth and sixth cylinders, or by the injector of each of the two cylinders. Due to insufficient valve time, the amount of fuel injection becomes insufficient, which may cause misfire, and the misfire may deteriorate drivability and exhaust emission.

  Therefore, in FIG. 10, the time required for the crank angle section from the rising timing (t14) of the seventh cylinder REF signal to the injection start timing of the homogeneous combustion (calculated based on the engine rotational speed Ne) is a limiter (= injector drive circuit). The time required for the crank angle section from the rising timing of the 7th cylinder REF signal to the start timing of homogeneous combustion is limited (= charge time Tchg of the injector drive circuit). The timing (t53) when the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal for the seventh cylinder is set as the injection start timing for homogeneous combustion in the fifth cylinder. On the other hand, when the time required for the crank angle section from the rising timing of the seventh cylinder REF signal to the injection start timing of homogeneous combustion is equal to or longer than the limiter (= charge time Tchg of the injector drive circuit), the seventh cylinder The timing at which the time required for the first predetermined crank angle section (the time corresponding to the first predetermined crank angle section) has elapsed from the rising timing of the REF signal for use is set as the injection start timing of homogeneous combustion in the fifth cylinder.

  In FIG. 11, the time required for the crank angle section from the rise timing (t10) of the REF signal for the first cylinder to the injection start timing of homogeneous combustion (calculated based on the engine rotational speed Ne) is a limiter (= injector drive circuit). The time required for the crank angle interval from the rising timing of the first cylinder REF signal to the injection start timing of homogeneous combustion is determined (= charge time Tchg of the injector drive circuit). The timing (t54) when the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal for the first cylinder is set as the injection start timing for homogeneous combustion in the third cylinder. In contrast, when the time required for the crank angle interval from the rising timing of the REF signal for the first cylinder to the injection start timing of the homogeneous combustion is equal to or longer than the limiter (= charge time Tchg of the injector drive circuit), the first cylinder The timing at which the time required for the first predetermined crank angle section (the time corresponding to the first predetermined crank angle section) has elapsed from the rising timing of the REF signal for use is set as the homogeneous combustion injection start timing in the third cylinder.

  Similarly, in FIG. 11, the time required for the crank angle section from the rising timing (t12) of the REF signal for the eighth cylinder to the start timing of homogeneous combustion (calculated based on the engine rotational speed Ne) is the limiter (= injector). The time required for the crank angle section from the rising timing of the REF signal for the eighth cylinder to the injection start timing of the homogeneous combustion is determined by checking whether or not the charging time of the driving circuit is equal to or longer than the charging time Tchg). When it falls below (Tchg), the timing (t55) at which the charging time Tchg of the injector drive circuit has elapsed from the rising timing of the REF signal for the eighth cylinder is set as the injection start timing of homogeneous combustion in the sixth cylinder. On the other hand, when the time required for the crank angle section from the rising timing of the REF signal for the eighth cylinder to the injection start timing of the homogeneous combustion is equal to or longer than the limiter (= charge time Tchg of the injector drive circuit), the eighth cylinder The timing at which the time required for the first predetermined crank angle section (the time corresponding to the first predetermined crank angle section) has elapsed from the rising timing of the REF signal for use is set as the injection start timing of homogeneous combustion in the sixth cylinder.

  Such control of the second embodiment is also executed by the engine controller 15. That is, in the second embodiment, a flow similar to that of the flowcharts of FIGS. 8A and 8B of the first embodiment may be created and is omitted here.

  According to the second embodiment (the invention described in claim 9), the injector 13 capable of directly injecting fuel into the combustion chamber for each cylinder, and the REF signal generated at a predetermined crank angle position for each cylinder, After the passage of the first predetermined crank angle interval from the rise timing (input timing) of the REF signal for each cylinder, the injection start timing of homogeneous combustion, and the first predetermined crank angle from the rise timing (input timing) of the REF signal for each cylinder. After the elapse of the second predetermined crank angle section that is larger than the section, the injection start timing of the stratified combustion is set in advance, and the switching from the homogeneous combustion injection to the stratified combustion injection is performed at the timing when the switch to the stratified combustion is requested Fuel injection control of a direct-injection spark-ignition engine that switches from stratified combustion injection to homogeneous combustion injection at the timing when switching to homogeneous combustion was requested When there are three cylinders that have passed the homogeneous combustion injection start timing at the timing when the request for switching to homogeneous combustion (t7 ′ in FIG. 10) is present, the homogeneous combustion injection start timing has passed. Among the three cylinders, the REF signal immediately after the request to switch the injection start timing of the first cylinder in the ignition order (the first cylinder in FIG. 10) to the homogeneous combustion (the REF signal for the first cylinder in FIG. 10). ) Start timing (input timing) is set to the REF signal synchronous injection, and the injection start of the third cylinder (the seventh cylinder in FIG. 10) in the ignition order among the three cylinders that have passed the injection start timing of homogeneous combustion REF signal for setting the timing to the rising timing of the REF signal (the REF signal for the eighth cylinder in FIG. 10) immediately after the timing when the request for switching to homogeneous combustion is made REF signal immediately after the timing when the request for switching to homogeneous combustion is made as the injection start timing of the next cylinder after the three cylinders that have passed the injection start timing of homogeneous combustion (the sixth cylinder in FIG. 10). REF signal synchronous injection set at the rising timing of the next REF signal (the REF signal for the seventh cylinder in FIG. 10), and the second in the ignition order among the three cylinders that have passed the injection start timing of homogeneous combustion Injection start timing of the cylinder (No. 8 cylinder in FIG. 10), injection start timing of the first cylinder (No. 1 cylinder in FIG. 10), and injection of the third cylinder (No. 7 cylinder in FIG. 10) The injection start timing of the next cylinder (the third cylinder in FIG. 10) after the three cylinders that have passed the injection start timing of the homogeneous combustion is set to a time intermediate between the start timing and the third cylinder (FIG. 10 In the 7th cylinder) Since it is set to a timing intermediate between the injection start timing of the next cylinder after the three cylinders that have passed the injection start timing of homogeneous combustion (the sixth cylinder in FIG. 10), the first embodiment (Claim 2) The effects similar to those of the described invention) are achieved. That is, according to the second embodiment (the invention according to claim 9), while preventing simultaneous injection in a plurality of cylinders having different ignition orders (the first cylinder, the eighth cylinder and the seventh cylinder in FIG. 10), Since the voltage boosting time of the injector drive circuit can be secured, fuel injection due to insufficient injector drive current even when there are three cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request for switching to homogeneous combustion is made It becomes possible to reduce the quantity variation and improve the operability when switching from stratified combustion to homogeneous combustion.

  In order to perform fuel injection at the intermediate timing, that is, to perform injection other than REF signal synchronous injection, it is necessary to start a timer from the rising timing of the REF signal. In the second embodiment ( According to the ninth aspect of the invention, since only one timer is required to be started at the rising timing of the REF signal, the calculation load on the engine controller 15 is not deteriorated.

  According to the second embodiment (the invention described in claim 18), the injector 13 capable of directly injecting fuel into the combustion chamber for each cylinder, and the REF signal generated at a predetermined crank angle position for each cylinder, After the passage of the first predetermined crank angle interval from the rise timing (input timing) of the REF signal for each cylinder, the injection start timing of homogeneous combustion, and the first predetermined crank angle from the rise timing (input timing) of the REF signal for each cylinder. After the elapse of the second predetermined crank angle section that is larger than the section, the injection start timing of the stratified combustion is set in advance, and the switching from the homogeneous combustion injection to the stratified combustion injection is performed at the timing when the switching request to the stratified combustion is requested. Fuel injection control for direct-injection spark-ignition engines that switch from stratified combustion injection to homogeneous combustion injection at the timing when switching to homogeneous combustion was requested In the system, when there are three cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request to switch to homogeneous combustion (t7 ′ in FIG. 10), and the homogeneity of the mixture in the combustion chamber becomes torque fluctuation When the degree of influence is greater than a predetermined value, the injection start timing of the first cylinder (the first cylinder in FIG. 10) in the ignition order among the three cylinders that have passed the injection start timing of this homogeneous combustion is the homogeneous combustion. The REF signal synchronous injection set at the rising timing (input timing) of the REF signal (the REF signal for the first cylinder in FIG. 10) immediately after the request for switching to the REF signal is used, and the injection start timing of homogeneous combustion has passed 3 REF next to the REF signal immediately after the timing at which the injection start timing of the third cylinder in the ignition order (the seventh cylinder in FIG. 10) among the two cylinders is switched to the homogeneous combustion is requested. No. (the REF signal for the eighth cylinder in FIG. 10) is the REF signal synchronous injection set at the rising timing of the cylinder (the sixth cylinder in FIG. 10) after the three cylinders that have passed the injection start timing of the homogeneous combustion. ) Injection start timing is set to the REF signal synchronous injection set to the rising timing of the next REF signal (the REF signal for the seventh cylinder in FIG. 10) immediately after the timing when the request for switching to homogeneous combustion is made, Among the three cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the second cylinder (8th cylinder in FIG. 10) in the ignition order is set to the first cylinder (1st cylinder in FIG. 10). The next cylinder after the three cylinders (shown in FIG. 10) is set to an intermediate time between the injection start time and the injection start time of the third cylinder (the seventh cylinder in FIG. 10). 10 is number 3 The injection start time of the third cylinder (the seventh cylinder in FIG. 10) and the next cylinder after the three cylinders that have passed the injection start time of the homogeneous combustion (in FIG. 10) (Cylinder No. 6) is set to an intermediate period between the injection start timings of the 6th cylinder), and there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and mixing in the combustion chamber When the degree of influence of the homogeneity on the torque fluctuation is equal to or less than a predetermined value, the first cylinder in the ignition order (the first cylinder in FIG. 11) out of the three cylinders that have passed the injection start timing of this homogeneous combustion. ) Injection start timing is the REF signal synchronous injection set at the rising timing of the REF signal (the REF signal for the first cylinder in FIG. 11) immediately after the request for switching to the homogeneous combustion, and the homogeneous combustion injection start timing Over Among the three cylinders in the ignition order, the second REF signal in the ignition order (the eighth cylinder in FIG. 11) is the REF signal (in FIG. REF signal synchronous injection set at the rise timing of the No. 8 cylinder REF signal), and the third cylinder in the ignition order (No. 7 cylinder in FIG. 11) among the three cylinders that have passed the injection start timing of homogeneous combustion Since the injection start timing is REF signal synchronous injection set to the rising timing of the next REF signal (the REF signal for the seventh cylinder in FIG. 11) next to the REF signal immediately after the request for switching to homogeneous combustion. The same effects as those of the first embodiment (the invention described in claim 15) are achieved. That is, the voltage boost time of the injector drive circuit can be secured while preventing simultaneous injection in a plurality of cylinders having different ignition orders (the first cylinder, the eighth cylinder and the seventh cylinder in FIGS. 10 and 11). The degree of influence of the homogeneity of the air-fuel mixture on the torque fluctuation is greater than a predetermined value, and there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is requested 3 cylinders that have passed the injection start timing of homogeneous combustion when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value and when there is a request to switch to homogeneous combustion. In any case, it is possible to reduce the variation in the fuel injection amount due to the shortage of the injector drive current, which improves the operability when switching from stratified combustion to homogeneous combustion. Cylinders that are capable of performing the homogeneous combustion in the combustion chamber when the degree of influence of the air-fuel mixture on the torque fluctuation is less than a predetermined value and the injection start timing of the homogeneous combustion has passed when there is a request to switch to the homogeneous combustion When there are three, it is possible to switch to injection to homogeneous combustion at an even earlier timing.

  In order to perform fuel injection at the intermediate timing, that is, to perform injection other than REF signal synchronous injection, it is necessary to start a timer from the rising timing of the REF signal. In the second embodiment ( According to the eighteenth aspect of the invention, since only one timer is required to be started at the rising timing of the REF signal, the calculation load on the engine controller 15 is not deteriorated.

  According to the second embodiment (the invention described in claim 11), the injection start of the third cylinder (the seventh cylinder in FIG. 10) in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion. Timing at which switching to homogeneous combustion is requested as an intermediate timing between the timing and the injection start timing of the next cylinder after the three cylinders that have passed the injection start timing of homogeneous combustion (the sixth cylinder in FIG. 10) The timing at which the charging time of the injector drive circuit elapses (t52 in FIG. 10) is set from the rising timing (input timing) of the REF signal immediately after the REF signal immediately after (the REF signal for the eighth cylinder in FIG. 10). There is a request to switch to the homogeneous combustion while ensuring the charging time of the injector drive circuit for the injection start timing of the next cylinder (the third cylinder in FIG. 10) of the three cylinders that have passed the injection start timing of combustion. Next REF signal timing REF signal immediately after Tsu enables most close that the input timing of the (REF signal 10 at 8 cylinder), it is possible to ensure sufficient time for vaporization of the fuel spray.

  According to the second embodiment (the invention described in claim 13), the homogeneous combustion of the next cylinder (the fifth cylinder in FIG. 10) next to the three cylinders after the injection start timing of the homogeneous combustion has passed. At the time of injection, the injection start timing of the homogeneous combustion is determined from the rising timing (input timing) of the next REF signal (the REF signal for the seventh cylinder in FIG. 10) immediately after the timing when the switching request to the homogeneous combustion is requested. When the time until the injection start timing of the homogeneous combustion of the next cylinder (the fifth cylinder in FIG. 10) after the three cylinders that have passed is shorter than the charging time of the injector drive circuit, the homogeneous combustion injection start timing The injection start timing of the homogeneous combustion of the next cylinder (the fifth cylinder in FIG. 10) next to the three cylinders that have passed over is next to the REF signal immediately after the timing at which the switching request to the homogeneous combustion is requested. REF signal (Fig. 1 In FIG. 10, since the charging time of the injector drive circuit has elapsed from the rising timing (input timing) of the seventh cylinder REF signal (t53 in FIG. 10), the three cylinders that have passed the injection start timing of homogeneous combustion. Even during homogeneous combustion injection of the next next cylinder (cylinder No. 5 in FIG. 10), the voltage boost time of the injector drive circuit can be secured, so that variation in fuel injection amount due to insufficient injector drive current can be reduced, and stratified combustion The operability at the time of switching from homogeneous combustion to homogeneous combustion is improved.

  According to the second embodiment (the invention described in claim 19), when there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the mixture in the combustion chamber When the degree of influence of the degree of homogeneity on torque fluctuation is equal to or less than a predetermined value, the injection of homogeneous combustion in the next cylinder after the injection start timing of homogeneous combustion (the third cylinder in FIG. 11) has passed. The next cylinder after the three cylinders that have passed the injection start timing of the homogeneous combustion from the input timing of the REF signal (the REF signal for the first cylinder in FIG. 11) immediately after the request for switching to the homogeneous combustion (FIG. 11). When the time until the injection start timing of homogeneous combustion is shorter than the charging time of the injector drive circuit, the next cylinder after the three cylinders that have passed the injection start timing of homogeneous combustion (No. 3 in FIG. 11) Cylinder) The timing at which the charging time of the injector drive circuit elapses from the input timing of the REF signal (the REF signal for the first cylinder in FIG. 11) immediately after the timing at which the quality combustion injection start timing is requested to switch to homogeneous combustion (FIG. 11). In the case of t54), when there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation Is equal to or less than a predetermined value, the voltage boosting time of the injector drive circuit is also set in the homogeneous combustion injection of the next cylinder (the third cylinder in FIG. 11) of the three cylinders that have passed the homogeneous combustion injection start timing. Since it can be ensured, variations in fuel injection amount due to insufficient injector drive current can be reduced, and operability when switching from stratified combustion to homogeneous combustion is improved.

  According to the second embodiment (the invention described in claim 20), when there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the mixture in the combustion chamber Is equal to or less than a predetermined value, the homogeneous combustion of the next cylinder (the sixth cylinder in FIG. 11) next to the three cylinders that have passed the injection start timing of the homogeneous combustion. Three cylinders that have passed the injection start timing of the homogeneous combustion from the input timing of the REF signal (the REF signal for the eighth cylinder in FIG. 11) immediately after the timing when the request for switching to the homogeneous combustion is made at the time of injection. When the time until the injection start timing of the homogeneous combustion of the next cylinder (the sixth cylinder in FIG. 11) is shorter than the charging time of the injector drive circuit, the three cylinders that have passed the injection start timing of the homogeneous combustion Next next Input of the REF signal (the REF signal for the eighth cylinder in FIG. 11) next to the REF signal immediately after the timing at which the request for switching to the homogeneous combustion is made is made for the homogeneous combustion start timing of the cylinder (the sixth cylinder in FIG. 11) Since the timing when the charging time of the injector drive circuit has elapsed from the timing (t55 in FIG. 11), when there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion has occurred, and When the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value, the next cylinder after the three cylinders that have passed the injection start timing of homogeneous combustion (the sixth cylinder in FIG. 11) ), It is possible to ensure the voltage boost time of the injector drive circuit even during the injection of homogeneous combustion, which can reduce variations in fuel injection amount due to insufficient injector drive current, and stratified combustion Operation of switching to Luo homogeneous combustion is improved.

The schematic block diagram of the fuel-injection control apparatus of 1st Embodiment of this invention. The timing chart for demonstrating the case where the cylinder which has passed the injection start timing of homogeneous combustion will be 2 cylinders at the timing which the switching request | requirement to the injection start timing of homogeneous combustion was in the present control. The timing chart for demonstrating the case where the cylinder which has passed the injection start timing of homogeneous combustion will be 2 cylinders at the timing which the switching request | requirement to the injection start timing of homogeneous combustion was in the present control. The timing chart for demonstrating the effect | action of the control of a connection of 1st Embodiment when 2nd time is larger than charge time x2 of an injector drive circuit, and 1st time does not exceed the charge time of an injector drive circuit. The timing chart for demonstrating the effect | action of the control of a connection of 1st Embodiment when 2nd time is the charging time of an injector drive circuit x2 or less, and 1st time does not exceed the charge time of an injector drive circuit. The timing chart for demonstrating the effect | action of the control of a connection of 1st Embodiment when 2nd time is the charging time of an injector drive circuit x2 or less, and 1st time exceeds the charge time of an injector drive circuit. The timing chart for demonstrating the effect | action of this control of 1st Embodiment in case the influence degree which the homogeneity of the air-fuel | gaseous mixture in a combustion chamber has on a torque fluctuation exceeds a predetermined value. The timing chart for demonstrating the effect | action of this control of 1st Embodiment in case the influence degree which the homogeneity of the air-fuel | gaseous mixture in a combustion chamber has on a torque fluctuation is below a predetermined value. The flowchart for demonstrating the set of the injection start time at the time of the switching from the injection start timing of stratified combustion of 1st Embodiment to the injection start timing of homogeneous combustion. The flowchart for demonstrating the set of the injection start time at the time of the switching from the injection start timing of stratified combustion of 1st Embodiment to the injection start timing of homogeneous combustion. FIG. 3 is an operation stroke diagram of a V-type 8-cylinder engine. The timing chart for demonstrating the effect | action of this control of 2nd Embodiment in case the influence degree which the homogeneity of the air-fuel | gaseous mixture in a combustion chamber has on a torque fluctuation exceeds a predetermined value. The timing chart for demonstrating the effect | action of this control of 2nd Embodiment when the influence degree which the homogeneity of the air-fuel | gaseous mixture in a combustion chamber has on a torque fluctuation is below a predetermined value.

Explanation of symbols

1 Engine body 13 Injector (fuel injection valve)
15 Engine controller

Claims (23)

An injector capable of directly injecting fuel into the combustion chamber for each cylinder;
A reference signal generated at a predetermined crank angle position for each cylinder, and
After the passage of the first predetermined crank angle section from the input timing of the reference signal for each cylinder, the injection start timing of homogeneous combustion, and the second predetermined crank that is larger than the first predetermined crank angle section from the input timing of the reference signal for each cylinder. Pre-set after the lapse of the angular section as the start timing of stratified combustion,
Direct injection that switches from homogeneous combustion injection to stratified combustion injection at the timing when switching to stratified combustion is requested, and switching from stratified combustion injection to homogeneous combustion at the timing requested to switch to homogeneous combustion In a fuel injection control device for a flower ignition engine,
When there are a plurality of cylinders that have passed the injection start timing of the homogeneous combustion at the timing when there is a request to switch to the homogeneous combustion,
Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made,
The injection start timing of the next cylinder of the plurality of cylinders that has passed the injection start timing of the homogeneous combustion is set to the input timing after the reference signal next to the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made. ,
Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timings of the second and subsequent cylinders in the firing order are set as the injection start timing of the first cylinder and the next cylinder after the plurality of cylinders. A fuel injection control device for a direct-injection spark-ignition engine, wherein the fuel injection control device is set to an intermediate time from an injection start time. When there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made,
Of the two cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the request for switching to the homogeneous combustion,
Setting the injection start timing of the next cylinder after the two cylinders that have passed the injection start timing of the homogeneous combustion to the input timing of the reference signal next to the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made;
Of the two cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the second cylinder in the firing order is the injection start timing of the first cylinder and the injection of the next cylinder after the two cylinders. The fuel injection control device for a direct-injection spark-ignition engine according to claim 1, wherein the fuel injection control device is set to an intermediate time from a start time.   A first time which is a time from the injection start timing of the stratified combustion immediately before this timing to the input timing of the reference signal immediately after the timing of the request to switch to the homogeneous combustion at the timing when the switch to the homogeneous combustion is requested; , The second time, which is the time from the input timing of the reference signal immediately before the request for switching to the homogeneous combustion to the input timing of the reference signal immediately after the timing for the switching to the homogeneous combustion, is It calculates based on the speed, determines whether or not the reference signal synchronous injection is possible based on the first time, and determines whether or not the intermediate timing can be set based on the second time The fuel injection control device for a direct-injection spark-ignition engine according to claim 1, wherein the control is performed.   Whether the reference signal synchronous injection based on the first time is possible is determined by comparing the first time with the charging time of the injector driving circuit, and is it possible to set the intermediate time based on the second time? The fuel injection control device for a direct-injection spark ignition engine according to claim 3, wherein the determination is performed by comparing the second time with twice the charging time of the injector drive circuit.   When the first time exceeds the charging time of the injector driving circuit, it is determined that the reference signal synchronous injection is possible, and when the second time is longer than twice the charging time of the injector driving circuit, 5. The fuel injection control device for a direct injection spark ignition engine according to claim 4, wherein it is determined that an intermediate timing can be set. The third time, which is the time from the start timing of the stratified combustion after the timing when the switching to the homogeneous combustion is requested, to the input timing of the reference signal immediately thereafter, and the next reference signal from the input timing of the 1 reference signal Time calculating means for calculating a fourth time which is a time until the input timing of
When the first time is less than or equal to the charging time of the injector driving circuit and the second time is less than or equal to twice the charging time of the injector driving circuit, the third time exceeds the charging time of the injector driving circuit. The injection of the stratified combustion is continued in each cylinder from immediately after the timing when the request for switching to the homogeneous combustion is made until the fourth time exceeds twice the charging time of the injector drive circuit. Item 5. A fuel injection control device for a direct-injection spark ignition engine according to Item 4. Time calculating means for calculating a fourth time which is a time from the input timing of one reference signal to the input timing of the next reference signal after the timing when the switching to the homogeneous combustion is requested,
When the first time exceeds the charging time of the injector driving circuit and the second time is not more than twice the charging time of the injector driving circuit, the fourth time is equal to the charging time of the injector driving circuit. The fuel injection start timing immediately after the request for switching to homogeneous combustion is set to the input timing of the reference signal for each cylinder immediately after the timing for switching to homogeneous combustion until it exceeds 2 times. 5. The fuel injection control device for a direct-injection spark ignition engine according to claim 4, wherein the reference signal synchronous injection is continued.   The timing at which the charging time of the injector drive circuit elapses is set from the input timing of the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made as the intermediate timing. Fuel injection control device for direct-injection spark ignition engine. When there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request to switch to the homogeneous combustion is made,
The injection start timing of the first cylinder in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion is set to the input timing of the reference signal immediately after the request for switching to the homogeneous combustion,
Input of the reference signal next to the reference signal immediately after the timing at which the injection start timing of the third cylinder in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion has been requested to switch to the homogeneous combustion. Set the timing,
Input timing of the next reference signal next to the reference signal immediately after the timing at which the injection start timing of the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing is requested to switch to the homogeneous combustion. Set to
Of the three cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the second cylinder in the firing order is the injection start timing of the first cylinder, the injection start timing of the third cylinder, Set to the middle of
The injection start timing of the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing is the same as the injection start timing of the third cylinder and the three cylinders that have passed the homogeneous combustion injection start timing. The fuel injection control device for a direct-injection spark-ignition engine according to claim 1, wherein the fuel injection control device is set to an intermediate time from an injection start time of the next next cylinder.   Charge of the injector drive circuit from the input timing of the reference signal immediately after the request for switching to the homogeneous combustion as the intermediate timing between the injection start timing of the first cylinder and the injection start timing of the third cylinder The fuel injection control device for a direct-injection spark-ignition engine according to claim 9, wherein a timing at which time elapses is set.   There is a request to switch to the homogeneous combustion as an intermediate timing between the injection start timing of the third cylinder and the injection start timing of the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing. 10. The fuel injection control device for a direct-injection spark-ignition engine according to claim 9, wherein the timing at which the charging time of the injector drive circuit elapses is set from the input timing of the reference signal immediately after the reference timing. .   In the homogeneous combustion injection of the next cylinder after the two cylinders that have passed the injection start timing of the homogeneous combustion, the reference signal (the first reference signal) next to the reference signal immediately after the timing when the request for switching to the homogeneous combustion is requested. When the time from the input timing of the cylinder REF signal) to the injection start timing of the homogeneous combustion of the next cylinder after the two cylinders that has passed the homogeneous combustion injection start timing is shorter than the charging time of the injector drive circuit The reference signal next to the reference signal immediately after the timing at which the request for switching to the homogeneous combustion is made is used for the homogeneous combustion injection start timing of the next cylinder after the two cylinders that have passed the homogeneous combustion injection start timing. The direct-injection spark-ignited engine according to claim 2, wherein the charging time of the injector drive circuit has elapsed from the input timing of Fuel injection control device.   The next reference next to the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made at the time of the homogeneous combustion injection of the next cylinder after the three cylinders that have passed the injection start timing of the homogeneous combustion. When the time from the signal input timing to the injection start timing of the homogeneous combustion of the next cylinder after the three cylinders that has passed the homogeneous combustion injection start timing is shorter than the charging time of the injector drive circuit, The injection start timing of the homogeneous combustion of the next cylinder after the three cylinders that have passed the injection start timing of the homogeneous combustion is set to the next of the reference signal immediately after the timing when the switching request to the homogeneous combustion is requested. The fuel of the direct injection spark ignition engine according to claim 9, wherein the charging time of the injector driving circuit has elapsed from the input timing of the reference signal. Injection control device. An injector capable of directly injecting fuel into the combustion chamber for each cylinder;
A reference signal generated at a predetermined crank angle position for each cylinder, and
After the passage of the first predetermined crank angle interval from the input timing of the reference signal for each cylinder, the injection start timing of homogeneous combustion is reached after the elapse of the first predetermined crank angle interval, and the second predetermined larger than the first predetermined crank angle interval from the input timing of the reference REF signal for each cylinder. After the passage of the crank angle section is preset as the stratified combustion injection start timing,
Direct injection that switches from homogeneous combustion injection to stratified combustion injection at the timing when switching to stratified combustion is requested, and switching from stratified combustion injection to homogeneous combustion at the timing requested to switch to homogeneous combustion In a fuel injection control device for a flower ignition engine,
When there are multiple cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request for switching to homogeneous combustion is made, and when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than a predetermined value ,
Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made,
The injection start timing of the next cylinder of the plurality of cylinders that has passed the injection start timing of the homogeneous combustion is set to the input timing after the reference signal next to the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made. ,
Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timings of the second and subsequent cylinders in the firing order are set as the injection start timing of the first cylinder and the next cylinder after the plurality of cylinders. Set it to an intermediate time from the injection start time,
When there are multiple cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request for switching to homogeneous combustion is made, and when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In addition,
Among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the timing when the request for switching to the homogeneous combustion is made,
After the reference signal next to the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made, the injection start timing of the second and subsequent cylinders in the ignition order among the plurality of cylinders that have passed the injection start timing of the homogeneous combustion A fuel injection control device for a direct-injection spark-ignition engine, wherein When there are two cylinders that have passed the injection start timing of homogeneous combustion at the timing when the request for switching to homogeneous combustion is made, and when the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than a predetermined value In addition,
Of the two cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the request for switching to the homogeneous combustion,
Setting the injection start timing of the next cylinder after the two cylinders that have passed the injection start timing of the homogeneous combustion to the input timing of the reference signal next to the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made;
Of the two cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the second cylinder in the firing order is the injection start timing of the first cylinder and the injection of the next cylinder after the two cylinders. Set the time in between the start time and
When there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In case,
Of the two cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the request for switching to the homogeneous combustion,
Input of the reference signal next to the reference signal immediately after the timing at which the injection start timing of the second cylinder in the ignition order among the two cylinders that have passed the injection start timing of the homogeneous combustion has been requested to switch to the homogeneous combustion. The fuel injection control device for a direct injection spark ignition engine according to claim 14, wherein the fuel injection control device is set to timing.   When there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In the case of the homogeneous combustion injection of the next cylinder after the two cylinders that have passed the injection start timing of the homogeneous combustion, the homogeneous combustion is performed from the input timing of the reference signal immediately after the timing when the switching request to the homogeneous combustion is requested. If the time until the injection start timing of the homogeneous combustion of the next cylinder after the two cylinders that have passed the injection start timing is shorter than the charging time of the injector drive circuit, The injection start timing of the homogeneous combustion of the next cylinder after the cylinder is determined from the input timing of the reference signal immediately after the timing when the switching request to the homogeneous combustion is requested. The fuel injection control apparatus for a direct eruption flowers ignition engine according to claim 15, characterized in that a timing at which the charging time has elapsed dynamic circuit.   When there are two cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In the case of the homogeneous combustion injection of the next cylinder after the two cylinders that have passed the injection start timing of the homogeneous combustion, the reference signal next to the reference signal immediately after the timing when the switching request to the homogeneous combustion is requested When the time from the input timing to the injection start timing of the homogeneous combustion of the next cylinder after the two cylinders that has passed the homogeneous combustion injection start timing is shorter than the charging time of the injector drive circuit, The reference signal immediately after the timing when the request to switch to the homogeneous combustion is made is made for the homogeneous combustion start timing of the next cylinder after the two cylinders that have passed the injection start timing. The next straight eruption flowers ignition type fuel injection control apparatus for an engine as set forth in the input timing of the reference signal to claim 15, characterized in that a timing at which the charging time has elapsed the injector drive circuit. When there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than a predetermined value In addition,
The injection start timing of the first cylinder in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion is set to the input timing of the reference signal immediately after the request for switching to the homogeneous combustion,
Input of the reference signal next to the reference signal immediately after the timing at which the injection start timing of the third cylinder in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion has been requested to switch to the homogeneous combustion. Set the timing,
Input timing of the next reference signal next to the reference signal immediately after the timing at which the injection start timing of the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing is requested to switch to the homogeneous combustion. Set to
Of the three cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the second cylinder in the firing order is the injection start timing of the first cylinder, the injection start timing of the third cylinder, Set to the middle of
The injection start timing of the next cylinder after the three cylinders that have passed the homogeneous combustion injection start timing is the same as the injection start timing of the third cylinder and the three cylinders that have passed the homogeneous combustion injection start timing. Set to a time intermediate between the injection start time of the next next cylinder,
When there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In case,
Of the three cylinders that have passed the homogeneous combustion injection start timing, the injection start timing of the first cylinder in the ignition order is set to the input timing of the reference signal immediately after the timing at which the request to switch to homogeneous combustion is made,
Input of the reference signal next to the reference signal immediately after the timing at which the injection start timing of the second cylinder in the ignition order among the three cylinders that have passed the injection start timing of the homogeneous combustion has been requested to switch to the homogeneous combustion. Set the timing,
Of the three cylinders that have passed the homogeneous combustion injection start timing, the reference signal next to the reference signal immediately after the timing at which the injection start timing of the third cylinder in the firing order is requested to switch to the homogeneous combustion is requested. The fuel injection control device for a direct-injection spark ignition engine according to claim 14, wherein   When there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In the case of the homogeneous combustion injection of the next cylinder of the three cylinders that has passed the injection start timing of the homogeneous combustion, the homogeneous combustion from the input timing of the reference signal immediately after the timing when the request to switch to the homogeneous combustion is made If the time until the injection start timing of the homogeneous combustion of the next cylinder after the three cylinders that have passed the injection start timing of the three cylinders is shorter than the charging time of the injector drive circuit, The injection start timing of the homogeneous combustion of the next cylinder after the cylinder is determined from the input timing of the reference signal immediately after the timing when the switching request to the homogeneous combustion is requested. The fuel injection control apparatus for a direct eruption flowers ignition engine according to claim 18, characterized in that a timing at which the charging time has elapsed dynamic circuit.   When there are three cylinders that have passed the injection start timing of the homogeneous combustion at the timing when the request for switching to the homogeneous combustion is made, and the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is less than a predetermined value In this case, in the homogeneous combustion injection of the next cylinder after the three cylinders that have passed the injection start timing of the homogeneous combustion, the reference signal next to the reference signal immediately after the timing when the switching request to the homogeneous combustion is requested When the time from the input timing to the injection start timing of the next cylinder after the three cylinders that has passed the injection start timing of the homogeneous combustion is shorter than the charging time of the injector drive circuit, The reference signal immediately after the timing at which the request to switch to the homogeneous combustion is made, indicates the homogeneous combustion injection start timing of the next cylinder after the three cylinders that have passed the injection start timing. The next straight eruption flowers ignition type fuel injection control apparatus for an engine as set forth in the input timing of the reference signal to claim 18, characterized in that a timing at which the charging time has elapsed the injector drive circuit.   Whether the degree of influence of the homogeneity of the air-fuel mixture in the combustion chamber on the torque fluctuation is greater than a predetermined value is determined by comparing the engine rotational speed with a threshold value or comparing the number of cylinders with a cylinder number threshold value. The fuel injection control device for a direct injection spark ignition engine according to claim 15 or 18.   19. The direct injection according to claim 2, wherein the injection start timing of the homogeneous combustion is in the first half of the intake stroke, and the injection start timing of the stratified combustion is in the first half of the compression stroke. A fuel injection control device for an eruption spark ignition engine.   The direct-injection spark ignition according to any one of claims 2, 9, 15, and 18, wherein the number of cylinders of the engine is eight cylinders, and the reference signal is generated every 90 degrees in crank angle. -Type engine fuel injection control device.

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