JP4389688B2 - Internal combustion engine fuel injection control device - Google Patents

Description

  The present invention sets the required fuel injection amount in the fuel injection control mechanism in advance with a margin period before the ignition timing, so that the fuel amount corresponding to the required fuel injection amount is changed to the fuel injection valve at the subsequent fuel injection timing. The present invention relates to an internal combustion engine fuel injection control apparatus that injects fuel into a combustion chamber.

When the load increase of the direct injection internal combustion engine is large, switching from compression lean (stratified combustion) performed by compression stroke injection to stoichiometric operation (premixed combustion) performed by intake stroke injection, sufficient output torque Has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-68350 (page 6-7, FIG. 3)

  However, it takes a relatively long time to switch from compression lean to stoichiometric operation. For example, there may be a case where rotation of 720 ° CA (CA: crank angle) or more is required, and if the fuel injection amount is increased and the output torque is increased thereafter, the engine speed is greatly reduced during this time, causing engine stall. There is a fear.

  Also in compression lean or stoichiometric operation, a sufficient margin period (for example, 450 ° CA) is usually provided before the compression top dead center (TDC), and the fuel injection amount is calculated before this margin period. Is set as a required fuel injection amount for the fuel injection control mechanism.

  For this reason, when rotation starts to decrease in a certain cylinder margin period, it cannot be dealt with by the fuel injection amount of the corresponding cylinder, and at the shortest, it cannot be dealt with in the cylinder where fuel injection is performed next. In the case of a 6-cylinder internal combustion engine, it is necessary to wait for an engine rotation of 450 ° to 570 °. For this reason, even when the combustion mode is not switched, there is a possibility that the engine speed will be greatly reduced and engine stall will occur.

  An object of the present invention is to enhance an engine stall prevention effect by quickly dealing with a decrease in rotation of a direct injection internal combustion engine.

In the following, means for achieving the above object and its effects are described.
The internal combustion engine fuel injection control apparatus according to claim 1 sets the required fuel injection amount based on the operating state of the direct injection internal combustion engine by the fuel injection amount setting timing set with a margin period before the ignition timing. By calculating and setting the required fuel injection amount in the fuel injection control mechanism at the fuel injection amount setting timing, the fuel injection control mechanism sets the fuel amount corresponding to the required fuel injection amount within the margin period. An internal combustion engine fuel injection control apparatus for injecting fuel from a fuel injection valve into a combustion chamber at a predetermined fuel injection timing, wherein a period from the fuel injection amount setting timing to a final fuel injection timing within the margin period is set as a compensation calculation period. Based on the rotational state of the direct injection internal combustion engine during the calculation period, the request is required to prevent a decrease in the rotational speed of the direct injection internal combustion engine. An insufficient fuel injection amount calculating means for calculating a fuel injection amount that is insufficient for the fuel injection amount, and a fuel injection valve calculated by the insufficient fuel injection amount calculating means at a timing until the final fuel injection timing. Refueling means for injecting the fuel into the combustion chamber, and the insufficient fuel injection amount calculating means is configured to determine a decrease in engine rotation based on a rotational state of the direct injection internal combustion engine in the compensation calculation period. A temporary required fuel injection amount necessary for preventing a decrease in engine rotation is calculated by increasing the required fuel injection amount, and fuel injection is performed in advance at the temporary required fuel injection amount and the fuel injection amount setting timing. A fuel injection amount that is insufficient due to a difference from the required fuel injection amount set in the control mechanism is calculated .

  Based on the rotational state of the direct injection internal combustion engine during the compensation calculation period, the insufficient fuel injection amount calculation means calculates a fuel injection amount that is insufficient with the required fuel injection amount in order to prevent a decrease in engine rotation. Therefore, the re-injection means uses the fuel injection amount that is insufficient in the required fuel injection amount, and injects the fuel from the fuel injection valve into the combustion chamber at the timing up to the final fuel injection timing, so that it rotates within the compensation calculation period. It becomes possible to cope from the cylinder where the fuel is injected immediately after the decrease. Even if it is not in time for the final fuel injection timing, it can be dealt with in the compensation calculation period of the next cylinder. In other words, compared to the case where the total fuel injection amount is set at the fuel injection amount setting timing, it can be reflected in the output torque of the direct injection internal combustion engine earlier by the compensation calculation period, and the engine rotation speed can be reduced quickly. Can be coped with, and the engine stall prevention effect can be enhanced.

In particular, insufficient fuel injection amount calculating means, the compensation calculation period Ru is calculated provisionally required fuel injection amount by increasing correction amount required fuel injection when the engine rotational speed decrease is determined. Although this temporary required fuel injection amount is the fuel injection amount necessary to actually cope with the engine rotation decrease, the setting to the fuel injection control mechanism has already been completed so that the required fuel injection amount is injected. , you calculate the fuel injection amount is insufficient by the difference between the temporary demand fuel injection amount and the required fuel injection amount.

  As a result, fuel corresponding to the temporary required fuel injection amount is injected as the entire injection amount for the cylinders for which the required fuel injection amount has already been set, so that it is possible to quickly cope with a decrease in engine speed. The engine stall prevention effect can be enhanced. Further, since the temporary required fuel injection amount is calculated by correcting the already calculated required fuel injection amount, for example, the latest required fuel injection amount in all cylinders, it is necessary to calculate the temporary required fuel injection amount. The load is reduced and the processing is quick.

The internal combustion engine fuel injection control apparatus according to claim 2, wherein the direct injection internal combustion engine is in an idle state, and the rotational speed of the direct injection internal combustion engine is less than a reduction determination rotational speed. And a decrease in engine speed of the direct injection internal combustion engine is determined when a decrease speed of the rotational speed per unit time of the direct injection internal combustion engine is equal to or greater than a determination decrease amount. .
In an internal combustion engine fuel injection control apparatus according to claim 3, in claim 1 or 2, wherein the insufficient fuel injection amount calculating means, the increasing correction of the required fuel injection amount on the basis of the boost value determined in accordance with the engine temperature Thus, the temporary required fuel injection amount is calculated.

  Since the atomization rate of the fuel changes depending on the engine temperature, it is preferable to obtain the increase value according to the engine temperature. As a result, it is possible to quickly and more appropriately cope with a decrease in engine rotation, and the engine stall prevention effect can be enhanced.

In an internal combustion engine fuel injection control apparatus according to claim 4, in any one of claims 1-3, wherein the deficient fuel injection amount calculating means until said compensation calculation period is completed, calculation of the fuel injection amount is insufficient the And the re-injection means causes the fuel injection valve to inject the insufficient fuel injection amount last calculated by the insufficient fuel injection amount calculation means in the compensation calculation period from the fuel injection valve into the combustion chamber at the final fuel injection timing. It is characterized by.

  In this way, by repeating the calculation of the fuel injection amount that the deficient fuel injection amount calculation means lacks until the end of the compensation calculation period, the latest deficient fuel injection amount is always obtained. When the compensation calculation period ends, the last calculated fuel injection amount represents the most appropriate shortage. Therefore, the re-injection means can inject this fuel injection amount into the combustion chamber from the fuel injection valve at the final fuel injection timing, so that the engine stall can be dealt with more quickly and appropriately. Can be increased.

The internal combustion engine fuel injection control device according to claim 5 is the internal combustion engine fuel injection control device according to any one of claims 1 to 4 , wherein the direct injection internal combustion engine includes an automatic transmission, and the internal combustion engine after the start of the direct injection internal combustion engine. When the load is idle, the catalyst warm-up control is executed to make the fuel injection timing the compression stroke and retard the ignition timing. When the automatic transmission shifts from the neutral range to the travel range, the catalyst warm-up control is stopped. The catalyst warm-up control means for setting the fuel injection timing to the intake stroke and performing at least one of the temporary reduction process of the fuel injection amount and the ignition timing gradual change return process, and the catalyst warm-up control means If a decrease in the rotation of the direct injection internal combustion engine occurs during execution of at least one of the injection amount temporary reduction processing and the ignition timing gradual change recovery processing, the temporary reduction processing and the ignition Time All of the period gradual change return processing is stopped, and return means for immediately returning the fuel injection amount and the ignition timing from the catalyst warm-up control state is provided.

  When the automatic transmission shifts from the neutral range to the travel range, the engine speed decreases and the insufficient fuel injection amount calculation means and the reinjection means function as described above. At least one of the temporary reduction process of the injection amount and the ignition timing gradual change recovery process is executed.

  Such transient processing of the catalyst warm-up control means acts negatively on the functions of the above-described insufficient fuel injection amount calculation means and re-injection means, and reduces the effect. Therefore, when the engine speed decreases, the return means stops both the temporary reduction process and the ignition timing gradual change return process, and immediately returns the fuel injection amount and the ignition timing from the catalyst warm-up control state. .

As a result, the insufficient fuel injection amount calculating means and the re-injecting means can sufficiently function to sufficiently exhibit the engine stall preventing effect.
In an internal combustion engine fuel injection control apparatus according to claim 6, according to claim 5, wherein the neutral range is the N range or P-range, characterized in that the said driving range is a D range, L range or R-range And

  More specifically, a shift change from the N range or the P range to the D range, the L range, or the R range can be given, and the engine stall prevention effect at the start operation can be enhanced.

[Embodiment 1]
FIG. 1 shows a schematic configuration of an in-line six-cylinder in-cylinder gasoline engine (hereinafter referred to as “engine”) 2 and an electronic control unit (hereinafter referred to as “ECU”) 4 mounted on a vehicle. . However, FIG. 1 shows the configuration of one cylinder as a center. Here, the output of the engine 2 is finally transmitted as traveling driving force to the wheels via the automatic transmission 6. The cylinder arrangement and the number of cylinders may be other than the in-line 6 cylinders, for example, a V-type 6 cylinder or an engine having another arrangement and the number of cylinders.

  The engine 2 is provided with a fuel injection valve 12 that directly injects fuel into the combustion chamber 10 and an ignition plug 14 that ignites the injected fuel. The intake port 16 connected to the combustion chamber 10 is opened and closed by driving the intake valve 18. A surge tank 22 is provided in the middle of the intake passage 20 connected to the intake port 16, and a throttle valve 26 whose opening degree is adjusted by a throttle motor 24 is provided upstream of the surge tank 22. The intake air amount is adjusted by the opening of the throttle valve 26 (throttle opening TA). The throttle opening degree TA is detected by a throttle opening degree sensor 28, and the intake air amount GA to the engine 2 is detected by an intake air amount sensor 30 provided upstream of the throttle valve 26 in the intake passage 20 and read into the ECU 4. It is.

  The exhaust port 32 connected to the combustion chamber 10 is opened and closed by driving the exhaust valve 34. In the middle of the exhaust passage 36 connected to the exhaust port 32, a start catalyst 38, which is a three-way catalyst having an O2 storage function for removing HC and CO components released in large quantities when the engine is started, is provided upstream. A NOx occlusion reduction catalyst (sometimes a three-way catalyst) 40 is provided downstream.

  Here, the intake valve 18 is lift-driven by the intake cam 50 and the exhaust valve 34 is lift-driven by the exhaust cam 52 to open and close. The intake camshaft 50a and the exhaust camshaft 52a are interlocked at a half speed with respect to the rotation of the crankshaft 54 of the engine 2, so that the intake valve 18 and the exhaust valve 34 are opened and closed corresponding to each stroke of the engine. Driven.

  The ECU 4 is an engine control circuit configured mainly with a digital computer. In addition to the throttle opening sensor 28 and the intake air amount sensor 30, the ECU 4 inputs a signal from an accelerator opening sensor 56 that detects the depression amount of the accelerator pedal 56a (accelerator opening ACCP). Further, the ECU 4 detects an engine speed sensor 58 that detects the engine speed NE from the rotation of the crankshaft 54, a reference crank angle sensor 60 that determines the reference crank angle G2 from the rotation of the intake camshaft 50a, and an engine coolant temperature THW. Signals are input from the cooling water temperature sensor 62, respectively. Further, the ECU 4 is provided on the upstream side of the start catalyst 38 and detects an air-fuel ratio from the exhaust component, between the start catalyst 38 and the NOx storage reduction catalyst 40, and downstream of the NOx storage reduction catalyst 40. Signals are input from two O2 sensors 66 and 68 that are provided and detect oxygen in the exhaust components. In addition to this, the ECU 4 inputs signals from sensors necessary for engine control such as a switch group 69 for detecting the range and gear position of the automatic transmission 6 and a vehicle speed sensor 70.

  The ECU 4 appropriately controls the fuel injection timing, the fuel injection amount, the ignition timing, the throttle opening degree TA, and the like of the engine 2 based on the detection contents from the various sensors described above. Thus, the combustion mode may be switched between stratified combustion and homogeneous combustion. For example, during normal operation excluding conditions such as cold, the combustion mode is determined based on a map of engine speed NE and load factor eklq as shown in FIG. Here, the load factor eklq is a value obtained from a map using, for example, the accelerator opening ACCP and the engine speed NE as parameters, indicating the ratio of the current load to the maximum engine load.

  When the combustion mode is set to stratified combustion, the throttle valve 26 is considerably open, and an amount of fuel considerably smaller than the stoichiometric air-fuel ratio with respect to the intake air amount is in the compression stroke, particularly in the latter half of the compression stroke. It is controlled to be injected. As a result, at the ignition timing, ignition is performed to the ignitable rich air-fuel mixture that exists in the vicinity of the ignition plug 14 and stratified combustion is performed.

  On the other hand, when the combustion mode is set to homogeneous combustion, the opening degree of the throttle valve 26 is adjusted in accordance with the degree of the accelerator opening degree ACCP, and the amount that becomes the stoichiometric air-fuel ratio (in some cases, becomes deeper than the stoichiometric air-fuel ratio). Amount) of fuel is controlled to be injected during the intake stroke. As a result, at the ignition timing, a homogeneous air-fuel mixture having a stoichiometric air-fuel ratio (possibly richer than the stoichiometric air-fuel ratio) occupying the entire combustion chamber 10 is ignited and homogeneous combustion is performed.

Note that it is not necessary to switch the combustion mode between the stratified combustion and the homogeneous combustion, and it is also possible to use engine control that normally performs homogeneous combustion by intake stroke injection.
Further, in the present embodiment, the ECU 4 performs the compression stroke injection and ignition in order to perform catalyst warm-up on the start catalyst 38 and the NOx occlusion reduction catalyst 40 at the time of no-load idle immediately after starting in the cold state. The catalyst warm-up control is performed to increase the catalyst bed temperature by executing the timing retard.

  Next, fuel injection amount control processing in the control executed by the ECU 4 in the present embodiment will be described. FIG. 3 shows a flowchart of the fuel injection amount control process. This process is a process executed by interruption at BTDC 450 ° with respect to the compression top dead center TDC of each cylinder. Here, since the engine 2 is a 6-cylinder engine, the fuel injection amount control process (FIG. 3) is a process executed six times in one cycle (720 ° CA) at intervals of 120 ° CA. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When this processing is started, first, the required fuel injection amount eqinj [] is determined based on the currently detected engine operating state for the i-th cylinder (hereinafter referred to as “#i”) that has reached BTDC 450 ° this time. i] is calculated (S102). Here, as the engine operating state, the aforementioned load factor eklq is calculated from the load factor map based on the engine speed NE and the accelerator opening ACCP, and the required fuel injection amount eqinj [i] is calculated from the fuel injection amount map based on this load factor eklq. ] Is calculated. Note that a value obtained from the fuel injection amount map obtained by adding various corrections other than the re-injection process (FIG. 4) described later may be set as the required fuel injection amount eqinj [i].

  Next, with respect to the drive control circuit of the fuel injection valve 12 provided in the ECU 4, the fuel for the required fuel injection amount eqinj [i] from the #i fuel injection valve 12 is brought into the combustion mode and engine operating state described above. Control data is set so as to be injected at the corresponding fuel injection timing (S104). The required fuel injection amount eqinj [i] may be injected once, but may be set to be injected a plurality of times, for example, twice.

  In this way, this process is once completed. Thereafter, the process described above is executed at BTDC 450 ° of the next cylinder, and the process of setting the control data in the drive control circuit so as to be injected from the fuel injection valve 12 of the next cylinder at the fuel injection timing is repeated. It is Since this is an in-line 6-cylinder engine, for example, the required fuel injection amount eqinj [i] is calculated every 120 ° CA rotation in the order of # 1 → # 5 → # 3 → # 6 → # 2 → # 4. It is set in the drive control circuit. In the case of a V-type 6-cylinder engine, the required fuel injection amount eqinj [i] is calculated every 120 ° CA rotation in the order of # 1 → # 2 → # 3 → # 4 → # 5 → # 6. It is set in the drive control circuit.

The reinjection process shown in the flowchart of FIG. 4 will be described. This process is a process that is repeatedly interrupted every 30 ° CA rotation.
When this process is started, it is first determined whether or not the rotation reduction determination flag exinjchg = ON (S202). The rotation decrease determination flag exinjchg is a flag that is repeatedly set every certain time (here, 16 ms) by the rotation decrease determination process shown in FIG. The rotation reduction determination process may be executed every rotation of a certain crank angle (for example, 30 ° CA).

  In the rotation reduction determination flag setting process (FIG. 5), three conditions are determined. The first condition is whether or not the vehicle is idling (S302). The second condition is whether or not the engine rotational speed NE (rpm) is less than the decrease determination rotational speed NEL (S304). The third condition is that a reduction speed dNE, which is a reduction amount of the engine speed NE per unit time during a constant time (for example, 16 ms) rotation or a constant crank angle (for example, 30 ° CA) rotation, is equal to or greater than the determination decrease amount DNEx. Whether or not there is (S306).

  When all of these conditions (S302, S304, S306) are satisfied, the rotation reduction determination flag exinjchg is set to ON (S308). If any one of them is NO, the rotation reduction determination flag exinjchg is set to OFF (S310).

  Note that the decrease determination rotational speed NEL is an engine rotational speed at which engine stall may occur, and may be obtained in advance through experiments. This value may be a fixed value or may be set to a rotational speed that is lower than the target rotational speed by a lower limit width in accordance with the target rotational speed during idling. Further, the determination decrease amount DNEx may be obtained in advance by experiments, may be a fixed value, or may be set according to the target rotational speed during idling.

  In this way, the rotation reduction determination flag exinjchg is set based on the latest engine rotation state every 16 ms (30 ° CA rotation for every 30 ° CA rotation interruption).

Returning to the description of the reinjection process (FIG. 4), if exinjchg = OFF (NO in S202), the reinjection process (FIG. 4) is temporarily terminated without performing any substantial process.
If exinjchg = ON (YES in S202), a cooling water temperature correction value Δrich is then calculated (S204). The coolant temperature correction value Δrich is a correction value calculated based on the engine coolant temperature THW as the engine temperature. Since the atomization rate of the injected fuel changes depending on the engine temperature, for example, as shown in the map of FIG. 6, the coolant temperature correction value Δrich is set corresponding to the engine coolant temperature THW.

Next, an after-engine-temperature-corrected injection increase coefficient ekrichxt is calculated by Equation 1 (S206).
[Formula 1] ekrichxt ← ekrichx + Δrich
Here, the injection increase coefficient ekrichx on the right side is a basic injection increase coefficient for preventing a decrease in rotation that leads to engine stall, and may be a fixed value or may be set based on a target rotation speed or the like.

  Next, the latest required fuel injection amount eqinj [i] calculated in the fuel injection amount control process (FIG. 3) by Expression 2 is corrected by the engine temperature-corrected injection increase coefficient ekrichxt, and the temporary required fuel injection amount eqinja. Is calculated (S208).

[Formula 2] eqinja ← eqinj [i] x ekrichxt
Next, for all the cylinders (#j) for which reinjection has not been completed in the cylinders for which the fuel injection amount has been set in the fuel injection amount control process (FIG. 3), the insufficient fuel injection amount eqinjH [j] Is calculated (S210).

[Formula 3] eqinjH [j] ← eqinja−eqinj [j]
Here, the required fuel injection amount eqinj [j] is a value that has already been calculated at BTDC 450 ° for #j and is set in the drive control circuit as the fuel injection amount for #j.

  Next, it is determined whether or not there is a cylinder (#k) that has now reached BTDC 90 ° among the cylinders (#j) that have not been re-injected (S212). If there is no such cylinder (#k) (NO in S212), the present process is temporarily terminated.

  If there is a cylinder (#k) that has reached BTDC 90 ° this time (YES in S212), it is determined whether the deficient fuel injection amount eqinjH [k] of the corresponding #k is positive (S214). If eqinjH [k] ≦ 0 (g) (NO in S214), re-injection is unnecessary, so this process is temporarily terminated as it is. In this case, there is no re-injection for #k, but #k re-injection is completed.

  If eqinjH [k]> 0 (g) (YES in S214), fuel injection for the insufficient fuel injection amount eqinjH [k] is executed from the fuel injection valve 12 at the current timing when #k is BTDC 90 °. (S216). That is, re-injection is performed. In this way, this process is once completed.

Thereafter, every time BTDC becomes 90 ° in each cylinder, if eqinjH [k]> 0 (g), fuel for the insufficient fuel injection amount eqinjH [k] is reinjected into the combustion chamber 10.
An example of the control in the present embodiment is shown in FIG. Here, the white circle represents the fuel injection amount setting timing at BTDC 450 °, the black circle represents the normal fuel injection timing at which the set fuel injection is performed, and the black triangle represents the timing at which re-injection is performed.

  Taking # 6 as an example, the required fuel injection amount eqinj [6] is injected at a fuel injection timing (120 ° CA in this case) indicated by a black circle at 630 ° CA (fuel injection amount setting timing) indicated by a white circle. Is set to Then, the calculation of the shortage fuel injection amount eqinjH [6] from 630 ° CA is repeated every 30 ° CA rotation, and the shortest fuel injection amount eqinjH [last calculated at 270 ° CA (final fuel injection timing). 6] of fuel is injected from the fuel injection valve 12. That is, the fuel injection amount (insufficient) in the required fuel injection amount eqinj [6] during the period from 630 ° CA (fuel injection amount setting timing) to 270 ° CA (final fuel injection timing) to prevent a decrease in engine rotation. This is a compensation calculation period for compensating for the fuel injection amount eqinjH [6]).

  Even during the compensation calculation period in which the insufficient fuel injection amount eqinjH [6] is repeatedly calculated, calculation of the insufficient fuel injection amount eqinjH [2] from # 2 to 30 ° CA is started, and from 150 ° CA to ## The calculation of the insufficient fuel injection amount eqinjH [4] of 4 is started. Then, the required fuel injection amounts eqinj [2] and eqinj [4] calculated for these # 2 and # 4 are used as the latest required fuel injection amount eqinj [i] to calculate the temporary required fuel injection amount eqinja (formula 2) and reflected in the shortage fuel injection amount eqinjH [6].

  In the above-described configuration, the relationship with the claims is that the steps S202 to S210 of the reinjection process (FIG. 4) correspond to the process as the insufficient fuel injection amount calculation means, and the steps S212 to S216 correspond to the process as the reinjection means. . A drive control circuit for the fuel injection valve 12 provided in the ECU 4 corresponds to a fuel injection control mechanism.

According to the first embodiment described above, the following effects can be obtained.
(I). In the compensation calculation period after the fuel injection amount setting timing at which the required fuel injection amount eqinj [j] is set, the required fuel injection amount eqinj [j] is insufficient based on the engine rotation state in order to prevent a decrease in engine rotation. The fuel injection amount (insufficient fuel injection amount eqinjH [j]) is calculated (S204 to S210).

  That is, when it is determined that the engine speed is reduced (S202), the required fuel injection amount eqinj [i] is increased and corrected by the engine temperature-corrected injection increase coefficient ekrichxt to calculate the temporary required fuel injection amount eqinja (S204-). S208). Then, an insufficient fuel injection amount eqinjH [j] is calculated based on a difference between the temporary required fuel injection amount eqinja and a required fuel injection amount eqinj [j] set in advance in the drive control circuit at the fuel injection amount setting timing ( S210). Then, the fuel corresponding to the insufficient fuel injection amount eqinjH [j] is reinjected into the combustion chamber 10 from the fuel injection valve 12 at the final fuel injection timing (S212 to S216).

  Therefore, if it is within the compensation calculation period, it is possible to cope with the cylinder from which fuel injection is performed immediately after the engine rotation is reduced. Even if the compensation calculation period elapses and the final fuel injection timing is not in time, it can be handled in the compensation calculation period of the next cylinder. That is, as compared with the case where the total fuel injection amount is set in the drive control circuit only at the fuel injection amount setting timing, it can be reflected in the output torque of the engine 2 earlier by the compensation calculation period. It is possible to deal with it quickly and to enhance the engine stall prevention effect.

  (B). The calculation process of the insufficient fuel injection amount eqinjH [j] is repeated until the end of the compensation calculation period, and the last calculated insufficient fuel injection amount eqinjH [j] in the compensation calculation period is determined from the fuel injection valve 12 at the final fuel injection timing. The fuel is injected into the combustion chamber 10 of the corresponding cylinder. Therefore, it is possible to cope with a decrease in engine rotation more quickly and appropriately, and the engine stall prevention effect can be enhanced.

  (C). Since the atomization rate of the injected fuel deteriorates when the engine temperature is low, the coolant temperature correction value Δrich, which is an increase value, is obtained according to the engine temperature (here, the engine coolant temperature THW), and the engine temperature-corrected injection increase coefficient ekrichxt is obtained. It is reflected. Then, the temporary required fuel injection amount eqinja is calculated by the product of the engine temperature-corrected injection increase coefficient ekrichxt and the already calculated required fuel injection amount eqinj [i] (here, the latest required fuel injection amount eqinj [i]). ing. Thus, by considering the fuel atomization state, it is possible to more appropriately cope with a decrease in engine rotation, and the engine stall prevention effect can be enhanced.

  Furthermore, since the temporary required fuel injection amount eqinja is calculated by correcting the already calculated required fuel injection amount eqinj [i], the calculation load for obtaining the temporary required fuel injection amount eqinja is reduced, and the processing Will be quicker.

[Embodiment 2]
The present embodiment is different from the first embodiment in that the process shown in FIG. 8 is executed as the combustion mode setting process. The other configuration is the same as that of the first embodiment, and will be described with reference to FIGS.

  The combustion mode setting process (FIG. 8) will be described. This process is a process executed at regular time intervals. When the process is started, it is first determined whether or not the engine is idling (S402). When not idling (NO in S402), the combustion mode is set according to the operating state of the engine 2 (S422). In this combustion mode, it is assumed that homogeneous combustion is normally performed by intake stroke injection.

  If it is idling (YES in S402), it is next determined whether or not the transient gradual change process execution flag Fd is OFF (S404). The transient gradual change process execution flag Fd is temporarily set when the automatic transmission 6 is shifted from the neutral range (N, P range) to the travel range (D, L, R range) during catalyst warm-up control. Is a flag set to

  That is, when the catalyst warm-up conditions (conditions such as no-load idling after start-up) are satisfied, the ECU 4 executes catalyst warm-up control by compression stroke injection and ignition timing retardation. If the shift is switched from the neutral range to the travel range during the catalyst warm-up control, the vehicle warm-up is stopped and the normal combustion mode and the ignition timing are restored, assuming that the vehicle starts to travel. In order to prevent a shock at the time of switching at this time, one or both of a temporary reduction process of the fuel injection amount and an ignition timing retarding attenuation process for gradually returning the ignition timing from the retarded state to the normal timing The transient gradual change process is performed. The transient gradual change process execution flag Fd is a flag indicating that the transient gradual change process is being performed.

  If the transient gradual change process execution flag Fd = OFF (YES in S404), it is next determined whether the catalyst is warming up (S406). If the catalyst is not currently warming up (NO in S406), the combustion mode is set according to the operating state of the engine 2 (S422).

  If the catalyst is currently warming up (YES in S406), it is determined based on the signal from the switch group 69 whether or not the automatic transmission 6 has been switched from the neutral range to the travel range (S408). That is, it is assumed that there is a switch from the neutral range to the travel range when the neutral range in the previous control cycle becomes the travel range in the current control cycle.

  Here, when switching from the neutral range to the travel range has not occurred (NO in S408), since the compression stroke injection and the ignition timing retarded by the catalyst warm-up control are executed, this processing is temporarily performed as it is. finish.

  If there is a switch from the neutral range to the travel range during catalyst warm-up control (YES in S408), the transient gradual change process execution flag Fd is set to ON (S410). Then, the process is returned to the intake stroke injection (S411), and it is determined whether or not the rotation reduction determination flag exinjchg is OFF (S412). If the rotation has not yet decreased and exinjchg = OFF (YES in S412), a transient gradual change process is executed (S414).

  That is, with the switching from the neutral range to the travel range, the catalyst warm-up control is stopped to prevent a shock when the engine is operated at the normal ignition timing in the intake stroke injection. For this reason, as a transient gradual change process, a process for temporarily reducing the fuel injection amount, and an ignition timing retarding attenuation process for gradually returning the ignition timing from the retarded state to the normal timing (in some cases, the ignition timing is advanced from the normal). One or both of these processes are performed. In the present embodiment, it is assumed that both the temporary reduction process of the fuel injection amount and the ignition timing retarding process are executed.

Next, it is determined whether or not the transient gradual change process is incomplete (S416). Since the transient gradual change process is not completed at first (YES in S416), this process is temporarily terminated as it is.
If the idling time continues in the next control cycle (YES in S402), it is next determined whether Fd = OFF (S404), but Fd = ON in the immediately preceding control cycle. Therefore (NO in S404), it is immediately determined whether exinjchg = OFF (S412). Again, if exinjchg = OFF (YES in S412), the transient gradual change process is further continued (S414). If the transient gradual change process is not completed (YES in S416), the process is temporarily terminated as it is.

  Thereafter, as long as it is idling, Fd = ON, and exinjchg = OFF, the transient gradual change process (S414) is continued. If the transient gradual change process is completed (NO in S416), the transient gradual change process execution flag Fd is set to OFF (S420), and this process is temporarily terminated.

  In the next control cycle, even when idling (YES in S402), since Fd = OFF (YES in S404), it is determined whether or not the catalyst is warming up (S406). Is completed (NO in S406), the combustion mode is set according to the operating state of the engine 2 (S422).

  If the rotational speed of the engine 2 is reduced due to shift switching from the neutral range to the traveling range while the transient gradual change process is continuing, and exinjchg = ON (NO in S412), the return process is performed (S418). . This recovery process stops both the temporary reduction process of the fuel injection amount by the transient gradual change process and the ignition timing retarding process, and immediately returns to the normal fuel injection quantity and ignition timing corresponding to the engine operating state. It is a process to return.

  Then, the transient gradual change process execution flag Fd is set to OFF (S420), and this process is temporarily terminated. Thus, in the next control cycle, when idling (YES in S402), it is determined whether Fd = OFF (S404). Since Fd = OFF (YES in S404), the catalyst is warming up. It is determined whether or not (S406). Since the catalyst warm-up control is stopped (NO in S406), the combustion mode is set according to the operating state of the engine 2 (S422).

  An example of processing in the present embodiment is shown in FIGS. FIG. 9 shows a case where exinjchg = OFF continues even after shift switching from the neutral range to the travel range (t0 to 0). Therefore, the transient gradual change process is performed to the end (t0 to t1).

  FIG. 10 shows a case where exinjchg = ON during the transient gradual change process (t10). For this reason, the transient gradual change process is stopped at the timing (t11) when exinjchg = ON, and the normal fuel injection amount and the ignition timing are restored.

  In the configuration described above, the relationship with the claims is that the steps S404 to S411, S414, S416, and S420 of the catalyst warm-up control and combustion mode setting process (FIG. 8) executed by the ECU 4 are the processes as the catalyst warm-up control means. Steps S412, S418, and S420 correspond to processing as return means.

According to the second embodiment described above, the following effects can be obtained.
(I). The effects (a) to (c) of the first embodiment are produced.
(B). If the engine speed decreases after the automatic transmission 6 changes from the neutral range to the travel range, the return process (S418) causes the temporary reduction process of the fuel injection amount by the transient gradual change process and the ignition timing retarding process. Both are stopped, and the normal fuel injection amount and the ignition timing corresponding to the engine operating state are immediately restored.

  Therefore, the effect of fuel re-injection when the engine speed is reduced by the re-injection process (FIG. 4) is not reduced, and the re-injection can be reliably reflected in the output torque of the engine 2, and the engine stall prevention effect can be sufficiently achieved. It can be demonstrated.

  In particular, when starting at a low temperature when heavy fuel is used, engine stall is likely to occur if the shift is shifted from the neutral range to the travel range, but such a case (exinjchg = ON) can be dealt with quickly and accurately. When heavy fuel is not used, exinjchg = ON does not easily occur even when the neutral range is shifted to the travel range, so that the fuel injection amount can be temporarily reduced and fuel can be saved.

[Other embodiments]
(A). In each of the above-described embodiments, in step S208 of the re-injection process, the temporary required fuel injection amount eqinja is obtained by correcting the latest required fuel injection amount eqinj [i] by the equation 2 using the engine temperature-corrected injection increase coefficient ekrichxt. Calculated. Instead of the latest required fuel injection amount eqinj [i], the temporary required fuel injection amount is directly obtained every 30 ° CA rotation directly by calculation equivalent to obtaining the required fuel injection amount eqinj [i]. The temporary required fuel injection amount eqinja may be used. Further, the provisional required fuel injection amount eqinja may be corrected by the equation (2).

  (B). In the second embodiment, the transient gradual change process executes both the temporary reduction process of the fuel injection amount and the ignition timing retarding process, but only the temporary reduction process of the fuel injection amount may be executed. Further, only the ignition timing retarding process may be executed.

1 is a schematic configuration diagram of an engine and an ECU according to a first embodiment. FIG. 3 is a configuration explanatory diagram of a map for determining a combustion mode according to the first embodiment. 3 is a flowchart of fuel injection amount control processing according to the first embodiment. 3 is a flowchart of reinjection processing according to the first embodiment. 6 is a flowchart of rotation reduction determination flag setting processing according to the first embodiment. FIG. 5 is a configuration explanatory diagram of a map for setting a coolant temperature correction value Δrich according to the first embodiment. FIG. 3 is a stroke diagram illustrating an example of control in the first embodiment. 6 is a flowchart of combustion mode setting processing according to the second embodiment. 9 is a timing chart showing an example of control in the second embodiment. 9 is a timing chart showing an example of control in the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Engine, 4 ... ECU, 6 ... Automatic transmission, 10 ... Combustion chamber, 12 ... Fuel injection valve, 14 ... Spark plug, 16 ... Intake port, 18 ... Intake valve, 20 ... Intake passage, 22 ... Surge tank, 24 ... throttle motor, 26 ... throttle valve, 28 ... throttle opening sensor, 30 ... intake air amount sensor, 32 ... exhaust port, 34 ... exhaust valve, 36 ... exhaust passage, 38 ... start catalyst, 40 ... NOx occlusion reduction Catalyst 50 ... Intake cam 50a ... Intake cam shaft 52 ... Exhaust cam 52a ... Exhaust cam shaft 54 ... Crank shaft 56 ... Accelerator opening sensor 56a ... Accelerator pedal 58 ... Engine speed sensor 60 ... Reference crank angle sensor, 62 ... cooling water temperature sensor, 64 ... air-fuel ratio sensor, 66, 68 ... O2 sensor, 69 ... switch group, 70 A vehicle speed sensor.

Claims (6)

The required fuel injection amount is calculated based on the operating state of the direct injection internal combustion engine by the fuel injection amount setting timing set with a margin period before the ignition timing, and the required fuel injection amount is set to the fuel injection amount setting. By setting the fuel injection control mechanism at the timing, the fuel injection control mechanism causes the fuel amount corresponding to the required fuel injection amount to be injected into the combustion chamber from the fuel injection valve at the fuel injection timing set within the margin period. An internal combustion engine fuel injection control device,
The in-cylinder injection type internal combustion engine is based on the rotational state of the in-cylinder injection type internal combustion engine in the compensation calculation period with the period from the fuel injection amount setting timing to the final fuel injection timing in the margin period as a compensation calculation period In order to prevent a decrease in rotation of the fuel, an insufficient fuel injection amount calculating means for calculating a fuel injection amount that is insufficient with the required fuel injection amount;
The fuel injection amount calculated by the lack fuel injection amount calculating means, and a re-injection means for injecting into the combustion chamber from the fuel injection valve at a timing to the final fuel injection timing,
The deficient fuel injection amount calculation means corrects the engine speed by increasing the required fuel injection amount when a decrease in engine rotation is determined based on the rotation state of the direct injection internal combustion engine during the compensation calculation period. The temporary required fuel injection amount necessary for preventing the decrease is calculated, and the temporary required fuel injection amount and a required fuel injection amount preset in the fuel injection control mechanism at the fuel injection amount setting timing are calculated. A fuel injection control device for an internal combustion engine that calculates a fuel injection amount that is insufficient due to a difference . 2. The in- cylinder injection internal combustion engine according to claim 1, wherein the in-cylinder injection internal combustion engine is in an idle state, the rotational speed of the in-cylinder injection internal combustion engine is less than a decrease determination rotational speed, and per unit time of the in-cylinder injection internal combustion engine. An internal combustion engine fuel injection control apparatus , wherein when the speed of decrease in the engine speed is equal to or greater than a determination decrease amount, a decrease in engine speed of the direct injection internal combustion engine is determined . 3. The short required fuel injection amount calculating means according to claim 1, wherein the short fuel injection amount calculating means calculates the temporary required fuel injection amount by increasing the required fuel injection amount based on an increase value obtained in accordance with an engine temperature. An internal combustion engine fuel injection control device. In any one of Claims 1-3 , while the said insufficient fuel injection amount calculation means repeats calculation of the said insufficient fuel injection amount until the said compensation calculation period is complete | finished,
The re-injection means is configured to inject the insufficient fuel injection amount last calculated by the insufficient fuel injection amount calculation means in the compensation calculation period from the fuel injection valve into the combustion chamber at the final fuel injection timing. Internal combustion engine fuel injection control device. In any one of Claims 1-4, while a cylinder injection type internal combustion engine is provided with an automatic transmission,
At the time of no-load idling after starting the direct injection internal combustion engine, the fuel injection timing is set to the compression stroke and the catalyst warm-up control is executed to retard the ignition timing, and the automatic transmission is shifted from the neutral range to the traveling range. In the case of a change, the catalyst warm-up control stops the catalyst warm-up control so that the fuel injection timing is set to the intake stroke, and at least one of the fuel injection amount temporary reduction process and the ignition timing gradual change return process is executed. Means,
When the catalyst warm-up control means executes at least one of the fuel injection amount temporary reduction process and the ignition timing gradual change return process, and the rotation reduction of the direct injection internal combustion engine occurs A return means for stopping both the temporary reduction process and the ignition timing gradual change return process and immediately returning the fuel injection amount and the ignition timing from the catalyst warm-up control state;
Internal combustion engine fuel injection control apparatus characterized by comprising a. 6. The internal combustion engine fuel injection control device according to claim 5 , wherein the neutral range is an N range or a P range, and the travel range is a D range, an L range, or an R range .

Images