JP4036198B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device for an internal combustion engine that includes an in-cylinder injector that directly injects fuel into a cylinder and an intake passage injector that injects fuel into an intake passage (including an intake port).

Conventionally, as this type of internal combustion engine, for example, there is a fuel injection control device for an internal combustion engine described in Patent Document 1.
This internal combustion engine fuel injection control system injects fuel into an intake port (intake passage) through an intake passage injection injector, thereby sufficiently mixing air and fuel to achieve highly homogeneous combustion (homogeneous combustion). Like to do. On the other hand, when the fuel is directly injected into the combustion chamber through the in-cylinder injector, the fuel consumption is improved by performing stratified combustion (lean combustion) by injecting the fuel in the latter half of the compression stroke, for example. The in-cylinder injector can also perform the above-described homogeneous combustion by sufficiently mixing air and fuel so that the air-fuel ratio is substantially the same in the entire combustion chamber. That is, in this case, the fuel is injected during the intake stroke of the engine, so that the diffusion time of the fuel is increased, and thereby the air and the fuel are mixed almost uniformly to perform combustion. If homogeneous combustion is performed by the in-cylinder injector, the inside of the cylinder is cooled as the fuel directly injected into the combustion chamber is vaporized, and deposits accumulate in the injection hole of the in-cylinder injector. Even if it is a case where it transfers to stratified combustion after that, the required spray shape and combustion injection quantity will also be maintained.
JP 2002-364409 A

  Incidentally, a knock sensor is disposed in a cylinder block provided with the in-cylinder injector. The knock sensor generally employs a resonance type that detects vibrations on the surface of the cylinder block. When a knocking-specific vibration is detected by the knock sensor in the knock determination period (gate) that is in the vicinity of the compression top dead center (late compression stroke) of each cylinder and is after the end of ignition, the knocking is detected. Knocking control is performed through the electronic control unit to suppress the above.

  In this knocking control, the number of times that the output peak value from the knock sensor exceeds the determination reference value during the knock determination period is counted, and it is determined that the greater the number of times, the greater the knock intensity. Then, the ignition timing is retarded according to the knock intensity, and when the state without knocking continues, the advance angle is gradually corrected, and the ignition timing is controlled at the knocking limit.

  By the way, the in-cylinder injector is provided in the vicinity of the knock sensor. For this reason, when fuel injection is performed by the in-cylinder injector, if the valve closing timing of the needle of the injector enters the gate, the electronic control unit knocks generated by valve closing (sitting) of the needle. There is a problem that the valve closing noise from the sensor is determined to be knocking, and the ignition timing is erroneously retarded based on the valve closing noise. In order to solve such a problem, it is conceivable that the fuel injection timing is changed to a timing at which the fuel injection timing is not delayed, that is, the needle closing timing is deviated from the gate. However, in this case, the change in the injection timing may lead to deterioration of the combustion state, which may cause a new problem that the potential of the internal combustion engine cannot be fully exhibited.

  The present invention has been made in view of such circumstances, and the object thereof is to prevent erroneous retardation of the ignition timing caused by the operation of the in-cylinder injector without causing deterioration of the combustion state. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is an internal combustion engine including a knock control system that delays the ignition timing to avoid knocking when knocking is detected based on a detection signal from a knock sensor that outputs a signal corresponding to vibration of the cylinder block. And an internal combustion engine for controlling fuel injection by an in-cylinder injector that directly injects fuel into a cylinder of the engine and an intake passage injector that injects fuel into the intake passage of the engine In the injection control device, when the closing timing of the injector enters the knock determination period of the knock control system at the time of in-cylinder injection of fuel by the in-cylinder injector, switching to fuel injection by only the intake passage injection injector Is the gist.

During fuel injection by the in-cylinder injector, when the valve closing timing of the needle in the injector enters a knock determination period (gate), the fuel injection is switched to fuel injection only by the intake manifold injector, and fuel injection by the in-cylinder injector is performed. Is stopped. For this reason, it is possible to suppress the valve closing noise from the knock sensor generated when the needle is closed (sitting) from being erroneously determined as knocking, and the ignition timing from being retarded erroneously. Further, after switching to fuel injection only by the intake passage injector as described above, the fuel injection timing can be freely changed .
Specifically, according to the invention of claim 2, after switching to fuel injection by only the intake passage injector, the fuel injection timing by the intake passage injector is changed to a fuel injection suitable for the injection mode. It is possible to adopt an aspect such as time. By adopting such a configuration, the combustion state is not deteriorated by the switching.

According to a third aspect of the present invention, there is provided an internal combustion engine including a knock control system that delays an ignition timing to avoid knocking when knocking is detected based on a detection signal from a knock sensor that outputs a signal corresponding to vibration of a cylinder block. And an internal combustion engine for controlling fuel injection by an in-cylinder injector that directly injects fuel into a cylinder of the engine and an intake passage injector that injects fuel into the intake passage of the engine In the injection control device, when the ignition timing is retarded by the knock control system at the time of fuel injection by the in-cylinder injector, switching means for switching to fuel injection only by the intake passage injection injector, and by the switching means Delay amount of the ignition timing delay before switching and the switching A determination means for comparing the amount of retardation of the ignition timing retarded by the knock control system in the engine and determining whether or not an erroneous retard of the ignition timing has occurred during fuel injection by the in-cylinder injector based on the comparison And an intake passage injection execution means for executing fuel injection only by the intake passage injection injector when the determination means determines that the erroneous retardation has occurred.

  During fuel injection by an in-cylinder injector, if the valve closing timing of the needle in the injector enters the knock determination period (gate), the valve closing noise from the knock sensor generated by the valve closing (sitting) of the needle is knocked An erroneous determination is made and the ignition timing is erroneously retarded. Therefore, when the fuel injection is performed by the in-cylinder injector and the ignition timing is erroneously retarded, the ignition timing retard amount tends to be large. Under such circumstances, when the switching means switches to fuel injection by only the intake manifold injector and the ignition timing is retarded by the knock control system, the retard amount at that time is determined by the in-cylinder injector. It becomes smaller than the retard amount during fuel injection. This is because when the fuel is injected only by the intake manifold injector, the fuel injection by the in-cylinder injector is stopped, so that the valve closing noise from the knock sensor generated when the needle of the injector is closed (sitting) is knocked. This is because the ignition timing is not erroneously retarded. Accordingly, by comparing the retard amount of the ignition timing before and after switching by the switching means, it can be determined whether or not an erroneous retard of the ignition timing has occurred during fuel injection by the in-cylinder injector. . When it is determined that an erroneous retardation has occurred, fuel injection is performed only by the intake manifold injector. For this reason, it is possible to prevent the ignition timing from being erroneously retarded due to fuel injection by the in-cylinder injector. Further, when the fuel injection is performed only by the intake passage injector, the fuel injection timing can be freely changed to obtain a fuel injection timing suitable for the injection mode. The condition does not get worse.

According to a fourth aspect of the present invention, in the fuel injection control device for an internal combustion engine according to the third aspect , when the determination means determines that the erroneous retardation has not occurred, the fuel by the in-cylinder injector The gist of the invention is to provide in-cylinder injection permission means for permitting injection.

  Selection of a fuel injection mode, such as fuel injection by an in-cylinder injector or fuel injection by an intake passage injector, is usually suitable for the operating state at that time, depending on the operating state of the internal combustion engine It is done in a form. As a result of such selection, when the fuel injection by the in-cylinder injector is selected, the switching means forcibly switches to the fuel injection only by the intake passage injector, and the ignition timing is erroneously delayed. A determination is made whether a corner has occurred. According to the above configuration, if it is determined here that the ignition timing is not erroneously retarded, fuel injection by the in-cylinder injector is permitted, and the operating state at that time is determined by the in-cylinder injector. If fuel injection is to be performed, fuel injection by the injector is resumed. Therefore, after judging whether or not the ignition timing is erroneously retarded, it is possible to prevent the fuel injection from the intake manifold injector alone from being continued forcibly and maintaining the good operating state of the internal combustion engine. Can do.

According to a fifth aspect of the present invention, in the fuel injection control device for an internal combustion engine according to the third or fourth aspect , the switching means has an upper limit value of a retard amount of the ignition timing at the time of fuel injection by the in-cylinder injector. Based on the value in the vicinity, it is determined that there is a possibility that the ignition timing may be erroneously retarded, and only when it is determined that there is a possibility of erroneous retardation, fuel injection using only the intake manifold injector The gist is to switch to.

  Regarding the retard of the ignition timing by the knock control system, the upper limit guard of the retard amount is normally performed so that the retard is not excessively performed. On the other hand, when the fuel injection is performed by the in-cylinder injector, if the ignition timing is erroneously retarded, the amount of retardation of the ignition timing tends to be large. Therefore, when the fuel injection by the in-cylinder injector is performed, if the retard amount of the ignition timing is a value near the upper limit value (upper limit guard value), it is determined that there is a possibility that the ignition timing is erroneously retarded. be able to. According to the above configuration, based on the determination that there is a possibility that such an ignition timing is erroneously retarded, the switching means switches to fuel injection only by the intake passage injector, and the ignition timing is erroneously retarded. Processing for determining the presence or absence is started. For this reason, it is possible to perform the processing only when there is a possibility that the ignition timing is erroneously retarded, so that it is not wastefully performed.

(First embodiment)
A first embodiment of a fuel injection control device for an internal combustion engine according to the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, this fuel injection control device is mainly configured of an internal combustion engine E that is a four-cycle reciprocating engine. Here, as the internal combustion engine E, a V-type 6-cylinder gasoline engine having six cylinders is assumed, but for convenience of explanation, only one cylinder is shown in FIG. The internal combustion engine E is mainly composed of a cylinder 1 having a cylinder block 1a and a cylinder head 1b connected to the upper portion of the cylinder block 1a, and a piston 2 reciprocating in the cylinder 1. Is done. The piston 2 is connected to a crankshaft 2a, which is an output shaft of the internal combustion engine E, via a connecting rod 2b and a crank arm 2c. The connecting rod 2b replaces the reciprocating motion of the piston 2 with the rotation of the crankshaft 2a. ing. In the cylinder 1, a combustion chamber 3 for combusting the air-fuel mixture is defined by the inner walls of the cylinder block 1a and the cylinder head 1b and the top surface of the piston.

  The cylinder head 1b is provided with an ignition plug 4 for igniting the air-fuel mixture in a manner protruding into the combustion chamber 3, and an in-cylinder injector 5 as fuel supply means for injecting and supplying fuel to the combustion chamber 3. It is installed. Further, an intake passage 6 and an exhaust passage 7 communicate with the combustion chamber 3 through an intake valve 8 and an exhaust valve 9, respectively. An intake port injection injector 10 is attached to the intake passage 6 as a fuel supply means for injecting and supplying fuel to the communicating portion of the intake passage 6 and the combustion chamber 3, that is, the intake port 6a.

Further, the internal combustion engine E of this embodiment is further provided with an accelerator sensor 21, a crank sensor 22, and a knock sensor 23.
Here, the accelerator sensor 21 is a sensor that is provided in the vicinity of an accelerator pedal (not shown) and detects its opening (depression amount), and the detected value is appropriately A / D converted by the electronic control unit 100. After that, the data is taken into a microcomputer provided in the electronic control device 100.

  The crank sensor 22 includes a rotor mounted on the crankshaft 2a of the internal combustion engine E, and an electromagnetic pickup that is disposed near the rotor and detects the passage of protrusions provided on the outer periphery of the rotor. This is a sensor for detecting the rotational phase (crank angle) of the crankshaft 2a and the rotational speed of the internal combustion engine E. The output of the crank sensor 22 is appropriately shaped in the electronic control unit 100 and then sent to the microcomputer in the electronic control unit 100 as a pulse signal (NE pulse) corresponding to the rotational speed of the crankshaft 2a. It is captured.

  The knock sensor 23 is provided in the cylinder block 1a of the internal combustion engine E. The knock sensor 23 is a sensor that detects vibration including knocking generated in the internal combustion engine E. The output of the knock sensor 23 is taken into the microcomputer in the electronic control unit 100 as a knock signal corresponding to the magnitude of the vibration.

  Here, the electronic control unit 100 is for driving the microcomputer, the A / D converter, the waveform shaping circuit, the memory for temporarily storing various data and calculation results, the various actuators, and the like. A driver (drive circuit) is provided. Then, based on the engine operation state grasped from the detection signals from the sensors, the ignition timing of the spark plug 4 and the fuel injection from the injectors 5 and 10 are controlled.

  The electronic control device 100 operates as a knock control system (KCS) that avoids occurrence of knocking in the internal combustion engine E. Here, the knocking avoidance by the knock control system will be described in detail.

The electronic control unit 100 sets a period during which knocking can occur in the internal combustion engine E, that is, the vicinity of the compression top dead center (compression stroke) of each cylinder and the period after the end of the ignition timing as a knock determination period (gate). Kenbun vibration from the detection signal of the knock characteristic from the knock sensor 23 corresponding to the vibration of the cylinder block 1a in the determination period only that. More specifically, during the knock determination period, the number of times that the output peak value from the knock sensor 23 exceeds the determination reference value is counted, and when the number exceeds the predetermined value, it is determined that knocking-specific vibration has occurred. To do. Based on this determination, knocking is detected.

  When knocking is detected as described above, the electronic control unit 100 avoids knocking by correcting the retard of the ignition timing. Specifically, the retard amount of the ignition timing is increased every time knocking is detected, and when the knocking is not detected, the ignition timing is controlled to the advance side by decreasing the retard amount. By controlling the ignition timing, the ignition timing is adjusted to the knocking limit, and the output of the internal combustion engine E is increased as much as possible while avoiding knocking. The retard amount of the ignition timing is guarded at the upper limit with a preset guard value G so that the ignition timing is not excessively retarded when knocking occurs at a high frequency.

  Further, the electronic control unit 100 executes switching control between fuel injection by the in-cylinder injector 5 and fuel injection by the intake port injector 10 in addition to avoiding knocking due to the ignition timing delay as described above. Such switching control is performed based on the engine operating state such as the engine speed and the engine load, and is performed in such a manner that a fuel injection mode suitable for the engine operating state at that time is selected. Whether the fuel injection by the in-cylinder injector 5 is selected or the fuel injection by the intake port injector 10 is selected, the fuel injection timing and the fuel injection amount depend on the engine. It is controlled to a value suitable for the operating state.

  By the way, when the fuel is injected by the in-cylinder injector 5 and the fuel injection is performed in the compression stroke, the valve closing timing of the needle in the injector 5 depends on the compression top dead center depending on the engine operating state. It may be delayed to the vicinity and enter the knock control system (KCS) gate. The in-cylinder injector 5 is provided in the vicinity of the knock sensor 23 in the cylinder block 1a, such as the cylinder head 1b, for performing in-cylinder injection. Therefore, the knock sensor 23 vibrates when the needle is closed (seatted). Be affected by. Therefore, when the needle closing timing enters the gate as described above, the knock sensor 23 outputs a signal corresponding to the vibration associated with the needle closing (sitting) as valve closing noise. If the valve closing noise exceeds the above-described determination reference value, the output peak value of the knock sensor 23 during the knock determination period (gate) is not generated even though knocking has actually occurred. The number of times that the determination reference value is exceeded becomes equal to or greater than a predetermined value, and there is a possibility that an erroneous determination is made that knocking has occurred. If an erroneous determination is made in this way, the ignition timing retard amount is increased in spite of the absence of knocking, and the ignition timing is erroneously retarded by the retard amount. .

  In addition, when the valve closing timing of the needle enters the gate in order to suppress such an erroneous retardation of the ignition timing, the timing of fuel injection by the in-cylinder injector 5 is changed, and the valve closing timing of the needle is changed from the gate. It is possible to make it come off. However, in this case, the fuel injection timing that has been determined to be suitable for the engine operating state is changed, and this change causes deterioration of the engine operation, and the potential of the internal combustion engine cannot be sufficiently extracted.

  Therefore, in the present embodiment, when the valve closing timing of the needle in the in-cylinder injector 5 enters the gate, the fuel injection is switched to the fuel injection by the intake port injection injector 10 only, and the above-described erroneous retardation of the ignition timing is suppressed. I am doing so. Hereinafter, the procedure for switching the fuel injection mode for suppressing the erroneous retardation of the ignition timing will be described in detail with reference to the flowchart of FIG. 2 showing the switching control routine. The switching control routine is executed through the electronic control unit 100, for example, by an angle interruption for each predetermined crank angle.

  In this routine, first, it is determined whether or not the current operation state of the internal combustion engine E is in-cylinder injection operation by the in-cylinder injector 5 (step S100). Here, if an affirmative determination is made, the valve closing timing of the needle in the in-cylinder injector 5 is obtained from the current required fuel injection amount and the fuel injection start timing (step S101). The valve closing timing of the needle can be obtained based on the required fuel injection amount and the fuel injection start timing because the fuel injection amount control of the in-cylinder injector 5 for obtaining the required fuel injection amount is the needle. This is because the valve closing timing is determined from the required fuel injection amount and the fuel injection start timing.

  Subsequently, it is determined whether or not the needle valve closing timing in the in-cylinder injector 5 is within the knock determination period (gate) (step S102). When it is determined that the valve closing timing is within the knock determination period (gate), the intake port injection is switched to only the intake port injection injector 10 (step S103). At this time, fuel injection by the in-cylinder injector 5 is stopped. Therefore, it is possible to suppress erroneous detection of knocking due to valve closing noise from the knock sensor 23 generated when the needle 5 is closed (sitting) in the injector 5, and the ignition timing being retarded erroneously. .

  When the fuel injection is performed only by the intake port injection injector 10 as described above, the fuel injection timing is freely changed without considering the valve closing timing of the needle with respect to the gate, which is suitable for the fuel injection mode. Since the fuel injection timing can be set, the combustion state does not deteriorate.

According to the fuel injection control device for an internal combustion engine according to this embodiment described in detail above, the following effects can be obtained.
(1) At the time of fuel injection by the in-cylinder injector 5, since the needle valve closing timing enters the gate, the fuel injection is switched to the fuel injection by the intake port injection injector 10 only, so that the combustion state is not deteriorated. An erroneous retardation of the ignition timing caused by the operation of the in-cylinder injector 5 can be suppressed.

(Second Embodiment)
Next, a second embodiment of the internal combustion engine fuel injection control apparatus according to the present invention will be described with reference to FIG. In this embodiment, the process for determining whether or not the ignition timing is erroneously retarded is executed. When it is determined that the ignition timing is erroneously retarded, the intake port injection injector 10 is determined. Only the fuel injection is executed.

FIG. 3 is a flowchart showing a switching control routine in this embodiment.
In this routine, first, it is determined whether or not the operation is being performed by in-cylinder injection (step S200), and it is further determined whether or not knocking is detected (step S201). If both the determination in step S200 and step S201 is affirmative, the process after step S202 is executed as a process for determining whether or not the ignition timing is erroneously retarded. It is selected whether to perform fuel injection only by port injection (step S207) or to permit in-cylinder injection (step S208).

  In the processing after step S202, it is first determined whether or not there is a possibility that the ignition timing is erroneously retarded (step S202). Here, based on the fact that the ignition timing retard amount is a certain value, for example, a value near the guard value G used for the upper limit guard (step S202: YES), there is a possibility that the ignition timing is erroneously retarded. to decide. Note that this determination can be made only when the ignition timing is erroneously retarded, because the ignition timing retard amount is large not only by actual knocking but also by the operation of the in-cylinder injector 5. This is because the amount of retardation tends to be larger.

  If there is a possibility that the ignition timing is erroneously retarded, the retard amount of the ignition timing at that time is stored in the memory as the retard amount ΔRTDchamb (−α) at the time of in-cylinder injection (step S203). Thereafter, the fuel injection is switched to the fuel injection only by the intake port injection injector 10 (step S204), and the retard amount of the ignition timing after operating the knock control system by the intake port injection for a predetermined period is set as the retard amount ΔRTDport at the time of the port injection. Store in the memory (step S205).

  Subsequently, in step S206, based on whether or not the retardation amount ΔRTDport during port injection is smaller than the retardation amount ΔRTDchamb (−α) during in-cylinder injection, an erroneous retardation of the ignition timing occurs during in-cylinder injection. Judge whether or not it was.

  Here, when the retardation amount ΔRTDport at the time of port injection is smaller than the retardation amount ΔRTDchamb (−α) at the time of in-cylinder injection, it is determined that an erroneous retardation of the ignition timing has occurred at the time of in-cylinder injection. Note that this determination can be made only when the fuel injection by the intake port injection alone is switched, and the in-cylinder injection is stopped, and the delay amount due to the operation of the in-cylinder injector 5 is erroneously increased. This is because the retardation amount at the time of port injection becomes smaller than that at the time of in-cylinder injection. Then, based on an affirmative determination in step S206, fuel injection by only intake port injection is executed (step S207). As a result, an erroneous retardation of the ignition timing is suppressed.

  In step S206, if the retardation amount ΔRTDport at the time of port injection is equal to or greater than the retardation amount ΔRTDchamb (−α) at the time of in-cylinder injection, it is determined that the ignition timing is not erroneously retarded at the time of in-cylinder injection. To do. Based on the negative determination in step S206, switching to in-cylinder injection is permitted (step S208). Therefore, if the engine operating state is a state where in-cylinder injection should be performed at this time, fuel injection by the in-cylinder injector 5 is executed.

According to the fuel injection control apparatus for an internal combustion engine according to the second embodiment described above, the following effects can be obtained.
(2) When knocking is detected during in-cylinder injection, it is forcibly switched to fuel injection only by port injection, and after the switching, the ignition timing retard amount ΔRTDport after operating the KCS for a predetermined time is When it is smaller than the retard amount ΔRTDchamb (−α) of the ignition timing, it is determined that an erroneous retard of the ignition timing has occurred during in-cylinder injection. When a determination to that effect is made, fuel injection is performed only by the intake port injector 10. As a result, it is possible to suppress an erroneous retardation of the ignition timing resulting from the operation of the in-cylinder injector 5 without causing deterioration of the combustion state.

  (3) As a result of switching to forced port injection as described above and determining whether or not there is an erroneous retardation of the ignition timing based on the retardation amount ΔRTDchamb (−α) and ΔRTDport, no erroneous retardation has occurred. If it is determined, execution of in-cylinder injection is permitted. For this reason, if the engine operating state after the above determination is a state where in-cylinder injection is to be performed, fuel injection by the in-cylinder injector 5 is resumed. Therefore, after the above determination, it is possible to prevent the fuel injection only by the intake port injection injector 10 from being continued forcibly and the internal combustion engine E from being unable to maintain a good operating state.

  (4) Regarding the process for determining whether or not the ignition timing is erroneously retarded (process after step S202), the retard value of the ignition timing is used as the upper limit guard in the process of step S202. It is started only when it is determined that there is a possibility that the ignition timing value is erroneously retarded. For this reason, when there is no possibility of erroneous retardation of the ignition timing, the above processing can be prevented from being performed wastefully.

In addition, the said embodiment can also be implemented as the following forms which changed this suitably, for example.
In the above embodiment, it is determined whether or not the ignition timing is retarded based on whether or not the ignition timing retardation amount is a value near the guard value G. An arbitrary value can be used in place of the value near the guard value G.

  In the above embodiment, the ignition timing is erroneously retarded during in-cylinder injection based on whether or not the retard amount ΔRTDport during port injection is smaller than the retard amount ΔRTDchamb (−α) during in-cylinder injection. Although it was determined whether or not it was, the comparison of the retard amount is not limited to such a determination method. For example, the comparison of the retardation may be performed based on the ratio of the retardation amount ΔRTDport and the retardation amount ΔRTDchamb (−α).

  In the above embodiment, if the retardation amount ΔRTDport at the time of port injection is smaller than the retardation amount ΔRTDchamb (−α) at the time of in-cylinder injection, it is determined that an erroneous retardation has occurred. However, if it is slightly small, it is not determined as an erroneous retardation, but is determined as an erroneous retardation when the difference between the retardation amount ΔRTDchamb (−α) and the retardation amount ΔRTDport exceeds a predetermined allowable value. It may be.

(Other embodiments)
Other elements that can be changed in common with the above embodiments are as follows.

  In each of the above embodiments, as an injector for injecting fuel into the intake passage, the intake port injection injector 10 (multipoint injection) provided for each cylinder and injecting fuel into each intake port 6a is illustrated. However, the injector may be an injector that can inject fuel into any part of the intake passage 6. That is, it is sufficient if it is an injector for intake passage injection. For example, the present invention can be applied to a so-called single point injection internal combustion engine that uses only one injector before branching of each cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram and a block diagram showing the configuration of a first embodiment of a fuel injection control device for an internal combustion engine according to the present invention; The flowchart which shows the switching procedure of the fuel-injection form for suppression of the false delay of the ignition timing in 1st Embodiment. The flowchart which shows the switching procedure of the fuel-injection form for suppression of the false delay of ignition timing in 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 1a ... Cylinder block, 1b ... Cylinder head, 2 ... Piston, 2a ... Crankshaft, 2b ... Connecting rod, 2c ... Crank arm, 3 ... Combustion chamber, 4 ... Spark plug, 5 ... In-cylinder injection injector, DESCRIPTION OF SYMBOLS 6 ... Intake passage, 6a ... Intake port, 7 ... Exhaust passage, 8 ... Intake valve, 9 ... Exhaust valve, 10 ... Intake port (passage) injector, 21 ... Accelerator sensor, 22 ... Crank sensor, 23 ... Knock sensor , 100: Electronic control device (switching means, determination means, intake passage injection execution means, in-cylinder injection permission means), E ... internal combustion engine.

Claims (5)

Applied to an internal combustion engine having a knock control system that delays ignition timing to avoid knocking when knocking is detected based on a detection signal from a knock sensor that outputs a signal corresponding to vibration of a cylinder block. In-cylinder injector that directly injects fuel into the engine, and a fuel injection control device for an internal combustion engine that controls fuel injection by an intake passage injector that injects fuel into the intake passage of the engine,
An internal combustion engine characterized by switching to fuel injection only by the intake manifold injector when the valve closing timing of the injector enters a knock determination period of the knock control system during in-cylinder injection of fuel by the in-cylinder injector. Engine fuel injection control device. The fuel injection control device for an internal combustion engine according to claim 1,
The fuel of the internal combustion engine, wherein after switching to fuel injection by only the intake passage injector, the fuel injection timing by the intake passage injector is set as the fuel injection timing suitable for the injection mode Injection control device. Applied to an internal combustion engine having a knock control system that delays ignition timing to avoid knocking when knocking is detected based on a detection signal from a knock sensor that outputs a signal corresponding to vibration of a cylinder block. In-cylinder injector that directly injects fuel into the engine, and a fuel injection control device for an internal combustion engine that controls fuel injection by an intake passage injector that injects fuel into the intake passage of the engine,
Switching means for switching to fuel injection only by the intake manifold injector when the ignition timing is retarded by the knock control system at the time of fuel injection by the in-cylinder injector;
The retard amount of the ignition timing retarded before the switching by the switching means is compared with the retard amount of the ignition timing retarded by the knock control system after the switching, and based on the comparison, the in-cylinder injector A determination means for determining whether or not an erroneous retardation of the ignition timing has occurred during fuel injection by
An intake passage injection execution means for executing fuel injection only by the intake passage injection injector when it is determined by the determination means that the erroneous retardation has occurred;
The fuel injection control device for an internal combustion engine, characterized in that it comprises a. The fuel injection control device for an internal combustion engine according to claim 3,
In-cylinder injection permission means for permitting fuel injection by the in-cylinder injector when the determination means determines that the erroneous retard angle has not occurred.
A fuel injection control device for an internal combustion engine. The switching means determines that there is a possibility that an erroneous retardation of the ignition timing has occurred based on the fact that the retard amount of the ignition timing is a value near the upper limit at the time of fuel injection by the in-cylinder injector, Only when it is determined that there is a possibility of erroneous retardation, the fuel injection is switched to the fuel injection by the intake manifold injector only.
  The fuel injection control device for an internal combustion engine according to claim 3 or 4.

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