JP2011099401A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device for an internal combustion engine suppressing drop of drivability accompanying change of injector generation noise. <P>SOLUTION: This device includes a direct injection injector directly injecting fuel to a combustion chamber of the internal combustion engine, and a passage injector injecting fuel to an intake air passage. Fuel injection only by the passage injector is executed when change over conditions are not satisfied and it is forcibly changed over to execution of fuel injection only by the direct injection injector when the change over conditions are satisfied in a low speed light load operation region of the internal combustion engine. Return to fuel injection only by the passage injector after forcible change over to fuel injection only by the direct injection injector is prohibited in a period until an operation state of the internal combustion engine goes out of the low speed light load operation region once (step S305: No). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection device for an internal combustion engine that includes both a direct injection injector that directly injects fuel into an engine combustion chamber and an intake passage injector that injects fuel into an engine intake passage.

  In recent years, there has been known a fuel injection device including a direct injection injector that directly injects fuel into a combustion chamber of the internal combustion engine in addition to an intake passage injector that injects fuel into the intake passage of the internal combustion engine (for example, Patent Document 1). ). In such a fuel injection device, fuel injection is performed such that either fuel injection using only an intake passage injector, fuel injection using only a direct injection injector, or fuel injection using both of them is performed in accordance with the operating state of the internal combustion engine. The form is switched. Normally, in a low-rotation low-load operation region of an internal combustion engine, if fuel injection by a direct injection injector is executed, it is easy to cause instability of the spray shape and combustion state compared to the case of executing fuel injection by an intake passage injector. Then, fuel injection is performed only by the intake passage injector.

  Since the direct injection injector is exposed to high-temperature combustion gas in the engine combustion chamber, deposits are likely to adhere to the injection hole portion. In addition, when fuel injection is performed only by the intake passage injector in the above apparatus, the fuel injection from the direct injection injector is not performed, so the cooling effect due to vaporization of the injected fuel cannot be expected, and the injection hole of the direct injection injector Deposits easily deposit on the part. Such deposit accumulation hinders fuel injection from the nozzle hole, and the shape of the fuel spray changes unnecessarily (specifically, the particle size of the fuel becomes unnecessarily large) or the fuel injection amount becomes less than the required amount. As a result, the combustion state of the fuel in the combustion chamber may be deteriorated.

  Therefore, in the past, when it is determined that there is a possibility of deposit accumulation in the low-rotation and low-load operation region of the internal combustion engine where fuel injection is performed only by the intake passage injector, only the direct injection injector is temporarily It has been proposed to perform deposit removal control for removing deposits by switching to fuel injection according to (see, for example, Patent Document 2). By executing this deposit removal control, even when deposits are accumulated in the injection hole portion of the direct injection injector, the deposits are blown away by the injected fuel from the direct injection injector.

JP 2009-30615 A JP 2005-201083 A

  By the way, in the fuel injection device, since it is necessary to inject fuel from the direct injection injector against high pressure in the combustion chamber, the pressure of the fuel supplied to the direct injection injector is set to a very high pressure. . For this reason, when simply switching between execution and stop of fuel injection by the direct injection injector in order to execute deposit removal control, the sound emitted by the internal combustion engine (specifically, the direct injection injector) greatly changes along with the switching, The change may cause a sense of incongruity to the occupant and cause a decrease in drivability.

  It should be noted that not only a device that performs deposit removal control or a device that performs fuel injection only by a passage injector in a low rotation / low load operation region, If the device can be switched between execution stop, the above-mentioned inconveniences occur similarly.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a fuel injection device for an internal combustion engine that can suppress a decrease in drivability associated with a change in injector-generated sound.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The invention according to claim 1 comprises a direct injection injector that directly injects fuel into the engine combustion chamber and an intake passage injector that injects fuel into the engine intake passage, and is in a low-rotation and low-load operation region of the internal combustion engine, When the switching condition is not satisfied, one of execution and non-execution of fuel injection by the direct injection injector is selected, and when the switching condition is satisfied, the other of the execution and non-execution of fuel injection by the direct injection injector is forced In the fuel injection device for an internal combustion engine that executes switching control to switch to the other, the return from the other to the one after forcibly switching to the other, the operating state of the internal combustion engine is in the low-rotation low-load operation region The gist of this is to prohibit it during the period until it is once removed.

  In the low-rotation and low-load operation region of the internal combustion engine, a sound other than the drive sound of the direct injection injector among the sounds generated by the internal combustion engine (for example, a sound [combustion sound] generated along with fuel combustion) is small. Furthermore, when the fuel injection by the direct injection injector is switched between execution and non-execution, the change in the generated sound due to the switching is conspicuous, and the drivability is likely to deteriorate. However, even in such a low rotation / low load operation region, if the operating state of the internal combustion engine is changing greatly, the change is not noticeable even when the sound emitted by the direct injection injector changes. Therefore, it can be said that drivability is unlikely to deteriorate.

  According to the above configuration, it is possible to return to the state before switching after forcibly switching from one of execution and non-execution of fuel injection by the direct injection injector to the other as the switching condition is satisfied. Even if the situation becomes a situation, when the engine operating state is changing in the low-rotation low-load operation region where the change in the sound generated by the direct injection injector is conspicuous, the return is prohibited. When the operating state of the internal combustion engine once deviates from the low-rotation low-load operation region and then returns to the low-rotation low-load operation region, in other words, when the operating state of the internal combustion engine has changed relatively greatly, Return is allowed. Therefore, the frequency at which execution and non-execution of the fuel injection by the direct injection injector can be switched in a situation where the change in the injector generated sound is conspicuous can be reduced, and the decrease in drivability accompanying the change in the injector generated sound can be suppressed. .

  According to a second aspect of the present invention, there is provided a fuel injection device for an internal combustion engine according to the first aspect of the invention, wherein the device enters the engine combustion chamber separately when the one is selected and when the one is switched to the other. Learning control for learning the index value of the fuel supply amount is executed, and the switching control is forcibly switched to the other in order to learn the index value when switching to the other through execution of the learning control. That is the gist.

  The injection amount error due to the deterioration of the injector and individual differences is different between the direct injection injector and the intake passage injector. Therefore, even when the operating state of the internal combustion engine is the same, engine combustion occurs when fuel injection by the direct injection injector is executed and when fuel injection is executed only by the intake passage injector without being executed. The amount of fuel actually supplied into the room (the amount of fuel supplied) is different. Therefore, in order to properly learn the index value of the fuel supply amount in the learning control in the above configuration, learning of the index value is performed separately when the fuel injection by the direct injection injector is performed and when it is not performed. desirable.

  According to the above configuration, in an apparatus that can switch between execution and non-execution of a direct injection injector in order to learn an index value of the fuel supply amount by learning control, it is possible to suppress a decrease in drivability associated with a change in injector generated sound. it can. The index value includes the air-fuel ratio of the air-fuel mixture, the intake air amount, the fuel injection amount of the injector, and the like.

  Note that, as the learning control, as in claim 3, a fuel injection device that executes air-fuel ratio feedback control that feedback-corrects the fuel injection amount so that the air-fuel ratio of the air-fuel mixture formed in the engine combustion chamber becomes a target ratio. Thus, it is possible to employ control for learning a steady deviation between the feedback correction amount and the reference value in the feedback control as the index value.

  According to a fourth aspect of the present invention, in the fuel injection device for an internal combustion engine according to the second or third aspect, the one is non-execution of fuel injection by the direct injection injector, and the other is by the direct injection injector Deposit removal, which is execution of fuel injection, and temporarily removes deposits attached to the direct injection injector by executing fuel injection by the direct injection injector when an execution condition is satisfied in the low-rotation low-load operation region The gist is to execute the control.

  In the above-described configuration, in the low-rotation and low-load operation region of the internal combustion engine, fuel injection is performed only by the intake passage injector when the execution condition is not satisfied, and deposit removal control (specifically, fuel injection by the direct injection injector is performed when the execution condition is satisfied). Injection). In addition, when the execution condition is not satisfied and the switching condition is satisfied, the learning control is executed after temporarily switching to the state in which the fuel injection by the direct injection injector is executed.

  According to the above configuration, when switching between execution and non-execution of the fuel injection by the direct injector for execution of learning control in this way, the frequency at which the switching is performed in a situation in which the change in the sound generated by the injector is conspicuous is set. Therefore, it is possible to suppress a decrease in drivability associated with a change in injector generated sound.

  According to a fifth aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first aspect, the switching control selects non-execution of fuel injection by the direct injection injector when the switching condition is not satisfied, The gist of the present invention is the deposit removal control that temporarily switches to the execution of fuel injection by the direct injection injector when the switching condition is satisfied, and removes the deposit attached to the direct injection injector.

According to the above configuration, it is possible to suppress a decrease in drivability associated with execution of deposit removal control.
According to a sixth aspect of the present invention, in the fuel injection device for an internal combustion engine according to any one of the first to fifth aspects, the fuel is produced only by the intake passage injector when the execution or non-execution is not executed. The gist of the present invention is to perform injection and to perform fuel injection only by the direct injector at the time of execution or non-execution.

  In the above configuration, the state where all of the fuel supplied to the engine combustion chamber is injected from the direct injection injector and the state where no fuel is injected from the direct injection injector are switched through the switching control. Therefore, compared to a device that shares a part of the fuel supplied to the engine combustion chamber by fuel injection by the intake passage injector when performing fuel injection by the direct injection injector, it is possible to switch between direct operation and non-operation of the direct injection injector. A change in the operation amount of the direct injection injector is likely to increase, and a change in the sound generated by the injector tends to increase.

According to the above-described configuration, it is possible to suitably suppress a decrease in drivability in such an apparatus in which the change in injector-generated sound tends to be large.
The invention according to claim 7 is the fuel injection device for an internal combustion engine according to any one of claims 1 to 6, wherein the low-rotation and low-load operation region is an idle operation region of the internal combustion engine. The gist.

  In the idling region of the internal combustion engine, the engine rotation speed is very low and the engine load is very small, so that the change in the sound generated by the injector is particularly noticeable. In the above configuration, since the switching control is executed in such an idle operation region, it can be said that the drivability is likely to be lowered due to the change in the sound generated by the injector.

  According to the above configuration, in the fuel injection device in which the switching control is executed in the idling operation region of the internal combustion engine, it is possible to suitably suppress the decrease in drivability.

1 is a schematic diagram showing a schematic configuration of a fuel injection device for an internal combustion engine according to an embodiment embodying the present invention. The flowchart which shows the execution procedure of an air fuel ratio control process. The flowchart which shows the execution procedure of deposit removal control processing. The flowchart which shows the execution procedure of a switching control process. The timing chart which shows an example of the execution aspect of a switching control process. The flowchart which shows the execution procedure of the modification of a deposit removal control process.

Hereinafter, a fuel injection device for an internal combustion engine according to the present invention will be described.
FIG. 1 shows a schematic configuration of a fuel injection device for an internal combustion engine according to an embodiment embodying the present invention.

  As shown in FIG. 1, a throttle valve 12 is provided in the intake passage 11 of the internal combustion engine 10. A throttle motor 13 is connected to the throttle valve 12. The opening of the throttle valve 12 (throttle opening TA) is adjusted through the drive control of the throttle motor 13, thereby adjusting the amount of air taken into the combustion chamber 14 through the intake passage 11.

  The internal combustion engine 10 is provided with a passage injector 15 for injecting fuel into an intake passage 11 (specifically, an intake port) and a direct injection injector 16 for injecting fuel directly into a combustion chamber 14.

  The passage injector 15 is connected to a fuel tank 18 via a feed pump 17, and the fuel pumped by the feed pump 17 is supplied to the passage injector 15. The direct injection injector 16 is connected to a fuel tank 18 via a feed pump 17 and a high-pressure pump 19, and fuel pumped by the feed pump 17 and the high-pressure pump 19 is supplied to the direct injection injector 16. Then, fuel is supplied into the combustion chamber 14 of the internal combustion engine 10 through the valve opening drive of the passage injector 15 and the direct injection injector 16.

  In the combustion chamber 14 of the internal combustion engine 10, ignition by the spark plug 20 is performed on the air-fuel mixture composed of intake air and supply fuel. By this ignition operation, the air-fuel mixture burns, the piston 21 reciprocates, and the crankshaft 22 rotates.

  The air-fuel mixture after combustion is sent out from the combustion chamber 14 to the exhaust passage 23 as exhaust. The exhaust passage 23 of the internal combustion engine 10 is provided with a three-way catalyst (hereinafter “exhaust gas purification catalyst 24”) for purifying the exhaust gas. The exhaust gas of the internal combustion engine 10 is purified through the exhaust gas purification catalyst 24 and then released to the outside of the exhaust passage 23.

  The apparatus of the present embodiment includes various sensors for detecting the operating state of the internal combustion engine 10. Examples of such various sensors include a crank sensor 31 for detecting the rotational speed of the crankshaft 22 (engine rotational speed NE), and an amount of intake air passing through the intake passage 11 (passage intake air amount GA). An intake air amount sensor 32 is provided. Further, an accelerator sensor 33 for detecting the depression amount AC of the accelerator pedal 25 and a throttle sensor 34 for detecting the throttle opening degree TA are provided. In addition, an air-fuel ratio sensor 35 for detecting the oxygen concentration OX of the exhaust gas in the exhaust passage 23 is also provided.

  The apparatus according to the present embodiment includes an electronic control unit 30 that includes a microcomputer, for example. The electronic control unit 30 takes in detection signals from various sensors and performs various calculations. Based on the calculation results, the electronic motor control unit 30 controls the driving of the throttle motor 13 (throttle control) and the driving control of the passage injector 15 and the direct injector 16. Various controls such as (fuel injection control) are executed.

  In the present embodiment, the amount of air sucked into the combustion chamber 14 (cylinder intake amount) is adjusted as follows. That is, first, a control target value (target in-cylinder intake air amount Tga) for the in-cylinder intake air amount is calculated based on the depression amount AC of the accelerator pedal 25 and the engine speed NE. Then, a value corresponding to the throttle opening degree TA at which the target in-cylinder intake air amount Tga and the actual in-cylinder intake air amount coincide with each other is calculated as a control target value (target throttle opening degree Tta) for the throttle opening degree TA. Then, the throttle control is executed so that the target throttle opening degree Tta and the actual throttle opening degree TA coincide with each other.

Further, the fuel injection control of the present embodiment is executed as follows.
First, a fuel amount (target fuel injection amount TQ) at which the air-fuel ratio of the air-fuel mixture becomes a target ratio (basically, the theoretical air-fuel ratio) is calculated based on the passage intake air amount GA. Further, the injection ratio Rd ([0 ≦ Rd ≦ 1.0]) of the direct injection injector 16 is calculated based on the engine load (for example, the passage intake air amount GA / the engine rotational speed NE) and the engine rotational speed NE. . Based on the target fuel injection amount TQ and the injection ratio Rd, the control target value (required fuel injection amount TQd) for the fuel injection amount of the direct injection injector 16 and the passage injector 15 so as to satisfy the following relational expression: A control target value (target fuel injection amount TQp) for each of the fuel injection amounts is set.

TQd = TQ × Rd
TQp = TQ × (1-Rd)

Thereafter, the drive of the direct injection injector 16 is controlled so that the same amount of fuel as the required fuel injection amount TQd is injected from the direct injection injector 16 and the same amount of fuel as the required fuel injection amount TQp from the passage injector 15. Is controlled so that the injector 15 is driven.

  In the present embodiment, in the high rotation operation region where the engine rotational speed NE is high and the high load region where the engine load is large, the injection ratio Rd is set to [1.0], and the fuel injection by the direct injection injector 16 alone is performed. Is executed. On the other hand, in the low rotation / low load operation region where the engine speed NE is low and the engine load is small (specifically, the idle operation region), the injection ratio Rd is set to [0], and fuel injection is performed only by the passage injector 15. Is done. On the other hand, in the medium speed region and medium load region of the internal combustion engine 10, the higher the engine speed NE or the larger the engine load, the larger the injection ratio Rd (however, [0 <Rd <1.0]) is set. Is done. In this region, the fuel injection from both injectors is executed such that the ratio of the fuel injection amount of the direct injection injector 16 to the total fuel injection amount of both the injectors (the direct injection injector 16 and the passage injector 15) increases. Is done.

  In the present embodiment, so-called air-fuel ratio feedback control is performed in which the fuel injection amount of each injector 15, 16 is feedback-controlled based on the detected value (oxygen concentration OX) of the air-fuel ratio sensor 35. This air-fuel ratio feedback control is executed so that the air-fuel ratio of the air-fuel mixture formed in the combustion chamber 14 of the internal combustion engine 10 becomes the target ratio.

  Further, in the present embodiment, a steady deviation between a correction amount (feedback correction amount K described later) in the air-fuel ratio feedback control and its reference value (specifically “1.0”) is used as the air-fuel ratio learning value GK. The air-fuel ratio learning control for learning is executed. In the present embodiment, a plurality of learning regions divided by the operating state (engine load and engine speed NE) of the internal combustion engine 10 are determined, and an air-fuel ratio learning value GK is set for each learning region. The learning of the air-fuel ratio learning value is executed for each learning region. In the present embodiment, an idle operation region of the internal combustion engine 10 is set as one of these learning regions.

  When executing the air-fuel ratio feedback control, the feedback correction amount K is calculated based on the oxygen concentration OX at that time, and the learning region is specified from the engine operating state, and the air-fuel ratio learning value GK corresponding to the learning region is obtained. Is read. The target fuel injection amount TQ is corrected by the feedback correction amount K and the air-fuel ratio learning value GK as shown in the following relational expression.

TQ = TQ × K + GK

Hereinafter, processing (air-fuel ratio control processing) related to control including the air-fuel ratio feedback control and air-fuel ratio learning control will be described in detail with reference to the flowchart shown in FIG.

  FIG. 2 is a flowchart showing a specific execution procedure of the air-fuel ratio control process, and a series of processes shown in this flowchart are executed by the electronic control unit 30 as an interrupt process at predetermined intervals.

As shown in FIG. 2, in this process, first, it is determined whether or not the execution condition of the air-fuel ratio feedback control is satisfied (step S101). Satisfaction of this execution condition is determined when both of the following conditions are satisfied.
-Warming up of the internal combustion engine 10 is completed (specifically, the temperature of the engine cooling water is equal to or higher than a predetermined temperature).
The air-fuel ratio sensor 35 is activated (specifically, the temperature of the air-fuel ratio sensor 35 is equal to or higher than a predetermined temperature).

  Then, when the execution condition of the air-fuel ratio feedback control is not satisfied (step S101: NO), this process is temporarily terminated without executing the following processes (steps S102 to S113).

  When the execution condition of the air-fuel ratio feedback control is satisfied (step S101: YES), it is determined whether or not the air-fuel ratio of the air-fuel mixture grasped based on the oxygen concentration OX is richer than the target ratio (step S102). When the air-fuel ratio is rich (step S102: YES), a predetermined value is subtracted from the feedback correction amount K (step S103). When the air-fuel ratio is lean (step S102: NO), the feedback correction amount K is set. The feedback correction amount K is updated such that a predetermined value is added (step S104). As the predetermined value, a relatively large value is used during so-called skip when the air-fuel ratio is switched between rich and lean, and a small value is used otherwise. In the present embodiment, air-fuel ratio feedback control is executed based on the feedback correction amount K updated in this way.

  Thereafter, a process for learning the air-fuel ratio learning value GK based on the feedback correction amount K is executed. Here, first, it is determined whether or not the air-fuel ratio of the air-fuel mixture has been skipped between the previous execution and the current execution of this process, that is, whether or not the air-fuel ratio has changed from rich to lean, or from lean to lean. (Step S105). If it is determined that the air-fuel ratio of the air-fuel mixture is not skipped (step S105: NO), this process is temporarily terminated without executing the following processes (steps S106 to S113).

  If it is determined that the air-fuel ratio of the mixture has been skipped (step S105: YES), an average value Kave of the feedback correction amount K is calculated (step S106). In the present embodiment, the latest value K1 of the feedback correction amount K1 when the air-fuel ratio is switched from rich to lean and the latest value K2 of the feedback correction amount K when the air-fuel ratio is switched from lean to rich are stored. As the average value Kave, a value ([K1 + K2] / 2) obtained by averaging the values K1 and K2 is calculated.

Then, a deviation ΔK (= [1.0] −Kave) between the average value Kave and the reference value (specifically [1.0]) of the feedback correction amount K is calculated (step S107).
Thereafter, it is specified in which of the plurality of learning regions the operation state of the internal combustion engine 10 at this time is included (step S108). The following processing (steps S109 to S113) is executed based on each value (temporary learning value GKb, learning counter count value, air-fuel ratio learning value GK described later) corresponding to the learning region specified in step S108. Is done.

  That is, first, the provisional learning value GKb is updated based on the deviation ΔK (step S109). Specifically, a value (ΔK × G) obtained by multiplying the deviation ΔK by a predetermined processing ratio G (0 <G <[1.0]) is added to the temporary learning value GKb to obtain a new temporary learning value GKb. Is calculated.

  Thereafter, the count value of the learning counter is incremented (step S110), and it is determined whether or not the count value has become larger than a predetermined value (for example, 30) (step S111).

  The temporary learning value GKb is repeatedly updated during the period when the count value is equal to or smaller than the predetermined value (step S111: NO), and when the count value becomes larger than the predetermined value along with the execution (step S111: YES). The provisional learning value GKb is stored as the air-fuel ratio learning value GK (step S112). At this time, the learning completion flag is turned on (step S113). The learning completion flag is a flag that is turned off when an operation switch (not shown) is operated by the occupant to start the operation of the internal combustion engine 10.

Then, after the air-fuel ratio learning value GK is updated in this way, this process is temporarily terminated.
Further, in the present embodiment, in order to remove deposits adhering to the direct injection injector 16 in the idling operation region of the internal combustion engine 10 where fuel injection is normally performed only by the passage injector 15, the direct injection is temporarily performed. Deposit removal control for executing fuel injection by the injector 16 is executed.

Hereinafter, a process (deposit removal control process) related to such deposit removal control will be described with reference to a flowchart shown in FIG.
The series of processes shown in this flowchart conceptually shows a specific execution procedure of the deposit removal control process, and the actual process is performed by the electronic control unit 30 as an interrupt process at predetermined intervals. Executed.

  As shown in FIG. 3, in this process, when the idling operation region is reached (step S201: YES), fuel injection by only the passage injector 15 is executed (step S202), and the number of executions is performed each time the fuel injection is executed. The count value of the counter is incremented (step S203).

  When the fuel injection is executed only by the passage injector 15 and the count value of the execution number counter reaches a predetermined determination value (for example, tens of thousands) (step S204: YES), the air-fuel ratio feedback control is being executed. It is determined whether or not there is (step S205). Here, when the air-fuel ratio feedback control is being executed (step S205: YES), it is forcibly switched to the fuel injection by only the direct injection injector 16 (step S206). Specifically, the injection ratio Rd is switched from [0] to [1.0]. Thereby, after that, fuel injection by the direct injection injector 16 is repeatedly executed, and the deposit attached to the direct injection injector 16 is removed.

  Further, in accordance with the execution of fuel injection only by the direct injection injector 16, a predetermined value N (N> [1.0], specifically N = [3.0], from the count value every time the fuel injection is executed. ) Is subtracted (step S207).

  After that, the fuel injection by only the direct injector 16 is repeatedly executed, and when the count value becomes [0] or less (step S208), the state is returned to the state in which the fuel injection only by the passage injector 15 is executed (step S209). .

In addition, when it is not an idle operation area | region (step S201: NO), the said count value is reset to [0] (step S210).
As described above, in the deposit removal control of the present embodiment, when the execution condition is not satisfied in the idle operation region (specifically, when the count value of the execution number counter is less than the determination value), the path injector 15 Only the fuel injection is executed. When the execution condition is satisfied (specifically, when the count value of the execution number counter becomes equal to or greater than the determination value), the fuel injection by the direct injection injector 16 is temporarily performed and the fuel is attached to the direct injection injector 16. The deposit is removed.

  Here, the injection amount error caused by the deterioration of the injector and individual differences is different between the direct injection injector 16 and the passage injector 15. Therefore, even when the operating state of the internal combustion engine 10 is the same, when the fuel injection by the direct injection injector 16 is executed and when the fuel injection by only the passage injector 15 is executed without executing the fuel injection. The amount of fuel actually supplied into the combustion chamber 14 of the internal combustion engine 10 (the amount of fuel supplied) is different. Therefore, in order to properly learn the air-fuel ratio learning value GK in the idling operation region in order to properly execute the above-described air-fuel ratio feedback control, fuel injection by only the direct injection injector 16 is executed and non-executed (in detail) It is desirable to determine the air-fuel ratio learning value GK separately and execute the learning when the fuel injection is performed only by the passage injector 15.

  In view of this point, in the present embodiment, as a learning region in the idle operation region, a learning region AR1 in which fuel injection is performed only by the passage injector 15 and a learning region AR2 in which fuel injection is performed only by the direct injection injector 16 are performed. Two areas are set. In the learning areas AR1 and AR2, the air-fuel ratio learning value GK is set separately and the learning is executed.

  In the present embodiment, the learning of the air-fuel ratio learning value GK in the learning area AR2 is not executed when the fuel injection is forcedly switched to only the direct injection injector 16 through the deposit removal control. When the switching condition (specifically, the execution condition of the air-fuel ratio feedback control) is satisfied in the region, it is executed after forcibly switching to the fuel injection by only the direct injection injector 16.

  As a result, the air-fuel ratio learned value GK in the learning area AR2 is executed early without waiting for the execution condition of the deposit removal control to be satisfied. In addition, when the learning of the air-fuel ratio learning value GK in the learning region AR2 is completed, the state is returned to the state where the fuel injection by only the passage injector 15 is executed, and thereafter the air-fuel ratio learning value GK in the learning region AR1 is learned. Will come to be.

  As described above, in the present embodiment, the switching control for forcibly switching to the fuel injection by only the direct injection injector 16 is performed to learn the air-fuel ratio learning value GK of the learning area AR2 without depending on the execution condition of the deposit removal control. Therefore, the air-fuel ratio learning value GK of the learning regions AR1 and AR2 in the idle operation region is learned early. Therefore, the air-fuel ratio feedback control is properly executed in the idle operation region of the internal combustion engine 10 without depending on the fuel injection mode, and an unnecessary change in the air-fuel ratio of the air-fuel mixture accompanying the execution of the deposit removal control is suppressed. become.

  By the way, in the apparatus of the present embodiment, since it is necessary to inject fuel from the direct injection injector 16 against high pressure in the combustion chamber 14 of the internal combustion engine 10, the fuel supplied to the direct injection injector 16 Is set to a very high pressure. Therefore, when the execution and stop of the fuel injection by the direct injection injector 16 are simply switched in order to execute the learning of the air-fuel ratio learning value GK in the learning region AR2, the internal combustion engine 10 (specifically, the direct injection) The sound generated by the injector 16) may change greatly, and the change may cause a sense of discomfort to the occupant, leading to a decrease in drivability.

  Moreover, in the apparatus according to the present embodiment, the state where all of the fuel supplied to the combustion chamber 14 is injected from the direct injection injector 16 and the state where no fuel is injected from the direct injection injector 16 are switched through the switching control. Therefore, when the fuel injection by the direct injection injector 16 is executed, the direct injection injector 16 is operated and not operated as compared with a device that shares a part of the fuel supplied to the combustion chamber 14 by the fuel injection by the passage injector 15. A change in the operation amount of the direct injection injector 16 accompanying the switching tends to be large. Therefore, it can be said that the change in injector-generated sound tends to be large, and the drivability is likely to deteriorate.

  In the low-rotation and low-load operation region of the internal combustion engine 10, the sound generated by the internal combustion engine 10 other than the drive sound of the direct injection injector 16 (for example, combustion sound) is small, so that the fuel generated by the direct injection injector 16 is low. When the execution and non-execution of the injection are switched, the change in the generated sound due to the change is conspicuous, and the drivability is likely to be lowered. Among such low-rotation and low-load operation regions, in the idle operation region of the internal combustion engine 10, the engine rotational speed NE is very low and the engine load is very small. Therefore, the change in the sound generated by the injector is particularly noticeable, and the drivability is likely to deteriorate. It can be said.

  However, even in such an idle operation region, if the operation state of the internal combustion engine 10 is greatly changed, for example, when the operation state of the internal combustion engine 10 becomes the idle operation region or immediately after that, Even if the sound emitted from the jet injector 16 is changed, the change is not conspicuous, so that it is difficult to cause a decrease in drivability.

  In view of such circumstances, in the present embodiment, the fuel by only the passage injector 15 after being forcibly switched to the fuel injection by only the direct injection injector 16 in order to execute the learning of the air-fuel ratio learning value GK in the learning region AR2. The return to the injection is prohibited during a period until the operation state of the internal combustion engine 10 once deviates from the idle operation region.

  Hereinafter, the process related to the switching control (switching control process) including the process of prohibiting the return to the fuel injection by only the passage injector 15 will be described in detail with reference to FIG.

  FIG. 4 is a flowchart showing a specific execution procedure of the switching control process, and the series of processes shown in this flowchart is performed at predetermined intervals that are executed on condition that the operating state of the internal combustion engine 10 is in the idle operating region. The interruption process is executed by the electronic control unit 30.

  As shown in FIG. 4, in this process, first, it is determined whether or not the execution condition of the air-fuel ratio feedback control is satisfied (step S301). If the execution condition of the air-fuel ratio feedback control is not satisfied (step S301: NO), [0] is set as the injection ratio Rd, and fuel injection only by the passage injector 15 is executed (step S302). . On the other hand, when the execution condition of the air-fuel ratio feedback control is satisfied (step S301: YES), it is determined whether or not learning of the air-fuel ratio learning value GK in the learning area AR2 is completed (step S303). . Here, the completion of learning of the same air-fuel ratio learning value GK is determined by turning on the learning completion flag in the learning area AR2.

  If the learning of the learning area AR2 is not completed (step S303: NO), the learning of the air-fuel ratio learning value GK in the learning area AR2 is performed despite the execution condition of the air-fuel ratio feedback control being satisfied. Assuming that the fuel injection has not been completed, fuel injection is executed only by the direct injection injector 16 to execute the learning (step S304).

  If learning of the learning area AR2 has been completed (step S303: YES), whether or not there is a history that the operation state of the internal combustion engine 10 has become an operation area other than the idle operation area after the completion of the learning. Is determined (step S305).

  If there is no history (step S305: NO), the fuel injection by only the direct injector 16 is continued (step S304). That is, in this case, the return to the state in which fuel injection is performed only by the passage injector 15 is prohibited. On the other hand, when there is the above history (step S305: YES), execution of fuel injection only by the passage injector 15 is permitted. That is, in this case, the state is returned to the state where the fuel injection by only the passage injector 15 is executed (step S302).

Hereinafter, the effect | action by performing such switching control is demonstrated, referring FIG.
FIG. 5 is a timing chart showing an example of an execution mode of the switching control.

  As shown in FIG. 5, before time T1, the accelerator pedal is not depressed (FIG. [A]), and the operating state of the internal combustion engine 10 is in the idling operation region (FIG. [B]). . Further, since the execution condition of the air-fuel ratio feedback control is not satisfied (FIG. [C]), learning of the air-fuel ratio learning value GK in the learning area AR2 is not executed (FIG. [D]), and the passage Fuel injection is performed only by the injector 15 ([e] in the figure).

  When the execution condition of the air-fuel ratio feedback control is satisfied due to a temperature rise accompanying the operation of the internal combustion engine 10 (time T1), the operation is forcibly switched to a state in which fuel injection by only the direct injection injector 16 is executed.

  After that, even when learning of the air-fuel ratio learning value GK in the learning area AR2 is executed and the learning is completed (time T2), the fuel injection by only the passage injector 15 is not restored to the state where the fuel injection is executed. Execution of fuel injection by only the injector 16 is continued. That is, even if the learning of the air-fuel ratio learning value GK in the learning area AR2 is completed and the fuel injection by the passage injector 15 alone can be restored, the generation of the direct injection injector 16 occurs. When it is an idle operation region where changes in sound are conspicuous (time T2 to T3), the return is prohibited.

  Thereafter, when the accelerator pedal 25 is depressed, the operation state of the internal combustion engine 10 temporarily changes to an operation region other than the idle operation region (time T3), and when the accelerator pedal 25 is released and enters the idle operation region (time T4). Then, fuel injection is performed only by the passage injector 15.

  Here, if the return is permitted when the learning of the air-fuel ratio learning value GK in the learning area AR2 is completed (time T2) as in the comparative apparatus shown by the one-dot chain line in FIG. 5, the change in the sound generated by the injector is noticeable. The fuel injection by the direct injection injector 16 is started in the easy idling region, and the drivability is lowered due to the change in the generated sound.

  On the other hand, in the apparatus of the present embodiment, when the operating state of the internal combustion engine 10 once deviates from the idle operating region and then returns to the idle operating region again (time T4), in other words, the operating state of the internal combustion engine 10 is compared. When there is a significant change, the fuel injection is started only by the passage injector 15 in the idle operation region. Therefore, in a situation in which the change in the sound generated by the injector is conspicuous, the frequency at which the fuel injection by the direct injection injector 16 is stopped can be reduced, and the decrease in drivability associated with the change in the sound generated by the injector can be suppressed accordingly. Can do.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) When the condition for executing the air-fuel ratio feedback control is satisfied, the operation state of the internal combustion engine 10 is the return to the fuel injection only by the passage injector 15 after forcibly switching to the fuel injection by only the direct injection injector 16. It was prohibited during the period until it was once removed from the idle operation area. Therefore, it is possible to reduce the frequency at which execution of fuel injection by the direct injection injector 16 is stopped in a situation where the change in the sound generated by the injector is noticeable, and to suppress the decrease in drivability associated with the change in the sound generated by the injector. it can.

  (2) In a device for forcibly switching to fuel injection by only the direct injection injector 16 in order to learn the air-fuel ratio learning value GK in the learning region AR2 where fuel injection by only the direct injection injector 16 is executed, A decrease in drivability due to changes can be suppressed.

  (3) In a device in which the change in the sound generated by the injector is likely to be large because the fuel injection by only the direct injector 16 and the fuel injection by only the passage injector 15 are switched through the switching control, it is preferable to suppress a decrease in drivability. Can do.

  (4) In an apparatus in which switching control is executed in an idle operation region where changes in injector-generated sound are particularly noticeable even in a low-rotation and low-load operation region, a decrease in drivability can be suitably suppressed.

The embodiment described above may be modified as follows.
The execution mode of the deposit removal control is, for example, estimating the deposit accumulation amount based on the operating state of the internal combustion engine 10, and fuel injection by the direct injection injector 16 on condition that the deposit amount exceeds a predetermined determination amount It is possible to arbitrarily change such as adopting an execution mode for starting the execution of.

  The execution mode of the air-fuel ratio feedback control is an execution in which the fuel injection amounts of the injectors 15 and 16 are feedback-controlled based on the detection value (oxygen concentration OX) of the air-fuel ratio sensor 35 so that the air-fuel ratio of the air-fuel mixture becomes the target ratio. If it is an aspect, it can change suitably.

  The execution mode of the air-fuel ratio learning control can be arbitrarily changed as long as a steady deviation between the correction amount in the air-fuel ratio feedback control and its reference value can be learned as the air-fuel ratio learning value.

  The operating range of the internal combustion engine 10 in which the deposit removal control and the switching control for learning the air-fuel ratio learning value GK when the control is executed is not limited to the idling operating range, but the engine speed Any low rotation and low load operation region where the NE is low and the engine load is small can be set arbitrarily. Specifically, an operation range of the internal combustion engine 10 slightly wider than the same region including the idle operation region, an operation region of the internal combustion engine 10 smaller than the same region included in the idle operation region, and the like can be set.

  When executing deposit removal control or switching control, the state is changed from the state in which fuel injection by only the passage injector 15 is executed to the state in which fuel injection by the direct injection injector 16 is executed in conjunction with the fuel injection by the passage injector 15. It may be. In the same configuration, by setting the injection ratio Rd to the same ratio when the deposit removal control is executed and when the switching control is executed, the air-fuel ratio learned value GK when the deposit removal control is executed through the air-fuel ratio learning control is set. You can learn accurately.

  In the above embodiment, in the apparatus that executes the switching control in order to learn the air-fuel ratio learning value GK at the time of deposit removal control, the fuel injection by the direct injection injector 16 upon completion of learning of the air-fuel ratio learning value GK Return from execution to non-execution is prohibited in a period until the operating state of the internal combustion engine 10 once deviates from the low rotation and low load operation region. Instead of this, or in conjunction with this, the operation state of the internal combustion engine 10 is changed from the low rotation and low load operation region to the return from the execution of the fuel injection by the direct injection injector 16 to the non-execution when the execution of the deposit removal control is stopped. You may prohibit in the period until it once removes.

  As specific processing for realizing such a configuration, the following processing can be employed. That is, first, after the count value of the execution number counter becomes equal to or less than [0] (step S208 in FIG. 3: YES), whether or not there is a history that the operation state of the internal combustion engine has become an operation region other than the idle operation region. Is determined (step S401 in FIG. 6). Then, when there is no history (step S401: NO), the fuel injection by only the direct injector 16 is continued, and when there is the history (step S401: YES), the fuel injection by only the passage injector 15 is performed. Switching (step S209 in FIG. 3).

  According to such a configuration, when the deposit removal control is executed, the frequency at which the fuel injection by the direct injection injector 16 is stopped in a situation in which the change in the injector generated sound is conspicuous can be reduced. A decrease in drivability due to changes can be suppressed.

  The fuel into the combustion chamber 14 of the internal combustion engine 10 is not limited to a device that executes air-fuel ratio learning control that learns the air-fuel ratio learning value GK separately when the fuel injection by the direct injection injector 16 is executed and when it is not executed. As long as it is a device that executes learning control that learns the index value of the supply amount, the fuel injection device of the above-described embodiment can be applied after changing its configuration as appropriate. As such a fuel injection device, a device that performs learning control for learning a learning value of the intake air amount (or throttle opening TA for adjusting the intake air amount) of the internal combustion engine 10, an air-fuel ratio (for example, an air-fuel ratio) Examples include an apparatus that executes learning control for learning a learning value of an air-fuel ratio control target value).

  -The present invention is not limited to a device that performs deposit removal control and learning control, but is in a low-rotation low-load operation region of an internal combustion engine, and when the switching condition is not satisfied, fuel injection by a direct injection injector is not performed and switching is performed. Any device that forcibly starts execution of fuel injection by the direct injection injector when the condition is satisfied can be applied.

  Also, in the low-rotation low-load operation region of the internal combustion engine, fuel injection by the direct injection injector is executed when the switching condition is not satisfied, and the fuel injection by the direct injection injector is forcibly stopped when the switching condition is satisfied. The present invention can also be applied to an apparatus. In this case, after the execution of the fuel injection by the direct injection injector is forcibly stopped, the operation state of the internal combustion engine is changed from the low rotation / low load operation region to the state where the fuel injection by the direct injection injector is executed. What is necessary is just to prohibit in the period until it removes once.

  In short, the present invention can be applied to any device that executes switching control forcibly switching from one of execution and non-execution of fuel injection by the direct injection injector when the switching condition is satisfied.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Throttle valve, 13 ... Throttle motor, 14 ... Combustion chamber, 15 ... Passage injector (intake passage injector), 16 ... Direct injection injector, 17 ... Feed pump, 18 ... Fuel tank , 19 ... high pressure pump, 20 ... spark plug, 21 ... piston, 22 ... crankshaft, 23 ... exhaust passage, 24 ... exhaust purification catalyst, 25 ... accelerator pedal, 30 ... electronic control unit, 31 ... crank sensor, 32 ... intake air A quantity sensor, 33 ... an accelerator sensor, 34 ... a throttle sensor, 35 ... an air-fuel ratio sensor.

Claims (7)

A direct injection injector that directly injects fuel into the engine combustion chamber and an intake passage injector that injects fuel into the engine intake passage, and in the low-rotation low-load operation region of the internal combustion engine, when the switching condition is not satisfied, the direct injection An internal combustion engine that selects one of execution and non-execution of fuel injection by an injector, and executes switching control forcibly switching to the other of execution and non-execution of fuel injection by the direct injection injector when the switching condition is satisfied In an engine fuel injection device,
An internal combustion engine that prohibits a return from the other to the one after forcibly switching to the other in a period until the operating state of the internal combustion engine once deviates from the low rotation / low load operating region. Fuel injectors. The fuel injection device for an internal combustion engine according to claim 1,
The apparatus performs learning control for learning the index value of the fuel supply amount into the engine combustion chamber separately when the one is selected and when the other is switched,
The fuel injection device for an internal combustion engine, wherein the switching control is control forcibly switching to the other in order to learn the index value when switching to the other through execution of the learning control. The fuel injection device for an internal combustion engine according to claim 2,
The apparatus performs air-fuel ratio feedback control for feedback correction of the fuel injection amount so that the air-fuel ratio of the air-fuel mixture formed in the engine combustion chamber becomes a target ratio,
The fuel injection device for an internal combustion engine, wherein the learning control is control for learning a steady deviation between a feedback correction amount in the feedback control as the index value and a reference value thereof. The fuel injection device for an internal combustion engine according to claim 2 or 3,
The one is non-execution of fuel injection by the direct injection injector, and the other is execution of fuel injection by the direct injection injector,
When the execution condition is satisfied in the low rotation and low load operation region, the deposit removal control is executed to temporarily perform fuel injection by the direct injection injector and remove deposits attached to the direct injection injector. A fuel injection device for an internal combustion engine. The fuel injection device for an internal combustion engine according to claim 1,
The switching control selects non-execution of fuel injection by the direct injection injector when the switching condition is not satisfied, and temporarily switches to execution of fuel injection by the direct injection injector when the switching condition is satisfied. A fuel injection apparatus for an internal combustion engine, characterized by deposit removal control for removing deposits adhering to an injector. In the fuel-injection apparatus of the internal combustion engine as described in any one of Claims 1-5,
The fuel injection is performed only by the intake passage injector when the execution or non-execution is not executed, and the fuel injection is executed only by the direct injection injector when the execution or non-execution is executed. A fuel injection device for an internal combustion engine. The fuel injection device for an internal combustion engine according to any one of claims 1 to 6,
The fuel injection device for an internal combustion engine, wherein the low rotation / low load operation region is an idle operation region of the internal combustion engine.

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