JP2019199818A - Fuel injection control device - Google Patents

Abstract

To suppress vibration of an engine in accompany with fuel-cut after accelerator-off, in an engine including a plurality of fuel injection valves per one cylinder.SOLUTION: An ECU (3) reduces a fuel injection amount in accompany with release of pedaling of an accelerator pedal (48) in an engine (2) including at least two fuel injection valves (first fuel injection valve (14a), second fuel injection valve (14b)) per one cylinder. The ECU stops the fuel injection by the first fuel injection valve and increases a fuel injection amount by the second fuel injection valve when the fuel injection amount is smaller than a minimum fuel injection amount, then reduces the fuel injection amount by the second fuel injection valve, and stops the fuel injection by the second fuel injection valve thereafter.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel injection control device.

  Some vehicle engines are provided with a plurality of (for example, two) fuel injection valves per cylinder (see Patent Document 1). In patent document 1, control which switches according to a request | requirement between the partial injection mode which injects only some fuel injection valves among several fuel injection valves, and the all-injection mode which injects all fuel injection valves. Execute.

  Further, in Patent Document 1, as a result of deposits (deposits) being generated by continuing the injection operation with only one fuel injection valve, there is a bias in the spray shapes when fuel is injected from both fuel injection valves. As a result, there is a possibility that proper combustion of the air-fuel mixture cannot be realized. Therefore, in Patent Document 1, each fuel injection is performed by intermittently switching the fuel injection valve to be injected during the execution of the partial injection mode, that is, by alternately repeating the injection operation with the two fuel injection valves. The valve deposit is removed.

JP 2009-185741 A

  By the way, in the fuel injection control of the engine, a so-called fuel cut is performed in which the fuel injection is stopped when the accelerator pedal is released (accelerator off). In this case, vibrations of the engine due to torque steps before and after the stop of fuel injection occur, which may be a factor that makes the passenger feel uncomfortable. For this reason, it is conceivable to reduce the fuel injection amount in advance and reduce the torque step before shifting to the fuel cut.

  However, the fuel injection valve has a minimum fuel injection amount that can inject fuel with an appropriate injection amount proportional to the driving time. When fuel injection is performed from a plurality of fuel injection valves toward one cylinder, the fuel injection amount per one is larger than that when fuel injection is performed from a single fuel injection valve toward one cylinder. Less. For this reason, there is a possibility that the required fuel injection amount may be lower than the minimum fuel injection amount, and if the fuel cut is performed early to prevent this, the occupant feels the vibration of the engine due to the torque step as described above. It will end up.

  The present invention has been made in view of the above points, and an engine including a plurality of fuel injection valves per cylinder is provided with a fuel injection control device capable of suppressing engine vibration caused by fuel cut after the accelerator is turned off. The purpose is to provide.

  A fuel injection control apparatus according to an aspect of the present invention is a fuel injection control apparatus that performs a reduction in fuel injection amount in response to release of an accelerator pedal in an engine including at least two fuel injection valves per cylinder. When the fuel injection amount is lower than the minimum fuel injection amount, the fuel injection is stopped by some fuel injection valves and the fuel injection amount is increased by other fuel injection valves, and then the other fuel injections are performed. After the fuel injection amount by the valve is reduced, the fuel injection by the other fuel injection valve is stopped.

  According to the present invention, in an engine provided with a plurality of fuel injection valves per cylinder, it is possible to suppress vibrations of the engine due to fuel cut after the accelerator is turned off.

1 is an overall configuration diagram of an engine control system according to the present embodiment. It is a schematic diagram inside the engine which concerns on this Embodiment. It is a flowchart of the fuel-injection control which concerns on this Embodiment. It is a time chart which shows a time-dependent change of the various parameters in this Embodiment. It is a flowchart of the fuel-injection control which concerns on a modification. It is a time chart which shows the time-dependent change of the fuel injection quantity which concerns on another modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, a four-wheeled vehicle will be described as an example of a vehicle to which the engine control system according to the present invention is applied. However, the application target is not limited to this and can be changed. For example, the present invention may be applied to other types of vehicles such as motorcycles.

  An engine control system according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is an overall configuration diagram of an engine control system according to the present embodiment. FIG. 2 is a schematic diagram of the inside of the engine according to the present embodiment. The engine control system is not limited to the configuration shown below, and can be changed as appropriate.

  As shown in FIGS. 1 and 2, the engine control system 1 according to the present embodiment is configured to control the operation of the engine 2 as an internal combustion engine and its peripheral components by an ECU 3 (Electronic Control Unit). ing. Although details will be described later, the ECU 3 constitutes the control device of the present application. The engine 2 is composed of, for example, a direct acting multi-cylinder DOHC (Double OverHead Camshaft) engine. The engine 2 includes a crankshaft 20 in a crankcase (not shown), and includes a cylinder 21, a cylinder head 22, and the like.

  A piston 23 is accommodated in the bore 21a of the cylinder 21 so as to be able to reciprocate in a predetermined direction (up and down in FIG. 1). The crankshaft 20 and the piston 23 are connected by a connecting rod 24. In the engine 2, the crankshaft 20 is rotated via the connecting rod 24 as the piston 23 reciprocates in a predetermined direction.

  The internal space of the cylinder head 22 constitutes a combustion chamber 25. A spark plug 26 as an ignition device is provided in the upper part of the combustion chamber 25. The spark plug 26 ignites at a predetermined timing based on the ignition signal output from the ECU 3 and ignites the air-fuel mixture in the combustion chamber 25.

  The cylinder head 22 is formed with an intake port 27 a and an exhaust port 27 b that communicate with the combustion chamber 25. The cylinder head 22 is provided with an intake valve 28a and an exhaust valve 28b corresponding to the intake port 27a and the exhaust port 27b. An intake camshaft 29a and an exhaust camshaft 29b are provided at the upper ends of the intake valve 28a and the exhaust valve 28b.

  A cam chain (not shown) is bridged over the crankshaft 20, the intake camshaft 29a, and the exhaust camshaft 29b. The rotation of the crankshaft 20 is transmitted to the intake camshaft 29a and the exhaust camshaft 29b via the cam chain. By rotating the intake camshaft 29a and the exhaust camshaft 29b, the intake valve 28a and the exhaust valve 28b are reciprocated toward the combustion chamber 25 at a predetermined timing.

  The intake pipe 10 is connected to the upstream end of the intake port 27a via an intake manifold (not shown). The passage in the intake pipe 10 and the intake port 27a constitute an intake passage for intake air. In the middle of the intake pipe 10, an air cleaner 11, a throttle valve 12, and a surge tank 13 are provided from the upstream side. An air amount sensor 40 is provided in the intake pipe 10 between the air cleaner 11 and the throttle valve 12. The air amount sensor 40 detects the amount of intake air (mass flow rate) flowing through the intake pipe 10 through the air cleaner 11 and outputs the detected value to the ECU 3.

  The throttle valve 12 is configured to include, for example, a butterfly valve, and adjusts the flow rate (intake air amount) of the intake air flowing through the intake pipe 10 by being opened and closed according to a command from the ECU 3. The surge tank 13 has a sufficiently large volume compared to the intake pipe 10 and prevents pulsation of intake air. The surge tank 13 is provided with an intake pressure sensor 41. The intake pressure sensor 41 detects the pressure (intake pressure) of the intake air in the surge tank 13 and outputs the detected value to the ECU 3. The ECU 3 can estimate the engine load from the intake air amount and the intake pressure.

  A fuel injection valve 14 as a fuel injection device for injecting fuel is provided in the intake pipe 10 (or intake port 27a) on the downstream side of the surge tank 13. The fuel injection valve 14 injects a predetermined amount of fuel into the intake pipe 10 (or the intake port 27a) according to a command from the ECU 3. That is, the engine 2 according to the present embodiment is a so-called port injection type engine.

  In particular, the engine 2 according to the present embodiment is a multi-cylinder (four cylinders in FIG. 2) engine, and two fuel injection valves are provided for each cylinder. Specifically, two intake ports 27a and two exhaust ports 27b are provided for each cylinder, and one fuel injection valve 14 is provided for each intake port 27a.

  Here, the fuel injection valve provided in one intake port 27a (intake passage) is referred to as a first fuel injection valve 14a, and the fuel injection valve provided in the other intake port 27a (intake passage) is referred to as a second fuel injection valve 14b. I will call it. Two fuel injection valves having the same performance are employed. Further, these fuel injection valves are numbered as first and second, but these numbers are given for convenience of explanation, and do not represent the priority or order. Further, the number of cylinders, the number of intake / exhaust ports for one cylinder, and the number of fuel injection valves are not limited to the example shown in FIG. 2, and can be changed as appropriate.

  The exhaust pipe 15 is connected to the downstream end of the exhaust port 27b via an exhaust manifold (not shown). The exhaust port 27b and the passage in the intake pipe 10 constitute an exhaust passage for exhaust gas. A catalyst 16 that purifies the exhaust (exhaust gas) of the engine 2 is provided in the middle of the exhaust pipe 15 as a part of the exhaust purification device. The catalyst 16 is composed of, for example, a three-way catalyst, and converts pollutants (carbon monoxide, hydrocarbons, nitrogen oxides, etc.) in the exhaust gas into harmless substances (carbon dioxide, water, nitrogen, etc.). When the engine 2 is a diesel engine, for example, an oxidation catalyst is used as the catalyst 16.

  Air-fuel ratio sensors 42 and 43 are provided before and after (upstream and downstream) of the catalyst 16. The air-fuel ratio sensors 42 and 43 detect the air-fuel ratio of the exhaust gas before and after the catalyst 16 and output the detected value to the ECU 3.

  In the engine 2 configured as described above, the intake air that has passed through the air cleaner 11 is adjusted in flow rate by the throttle valve 12 and then flows into the intake port 27 a through the surge tank 13. At this time, fuel is injected from the fuel injection valve 14 at a predetermined timing, and intake air and fuel are mixed in the intake port 27a. The mixture of intake air and fuel flows into the combustion chamber 25 when the intake valve 28a is opened, and after being compressed in the combustion chamber 25, is ignited at a predetermined timing by the spark plug 26. The exhaust gas after being ignited and burned is discharged outside through the exhaust pipe 15 from the exhaust port 27b. At this time, after the exhaust gas is purified by the catalyst 16, the exhaust sound is reduced by a muffler (not shown).

  Further, the engine 2 is provided with a water temperature sensor 44 that detects the engine water temperature and a crank sensor 45 that detects the phase of the crankshaft 20. The detection values of the water temperature sensor 44 and the crank sensor 45 are output to the ECU 3. The engine speed can be calculated from the output of the crank sensor 45.

  Further, the vehicle is provided with a vehicle speed sensor 46 for detecting the vehicle speed, a brake pedal 47, and an accelerator pedal 48. The detection value of the vehicle speed sensor 46 is output to the ECU 3. The brake pedal 47 constitutes a braking unit that generates a braking force on the vehicle, and outputs a predetermined electrical signal corresponding to the amount of depression (stepping force) to the ECU 3. The accelerator pedal 48 constitutes an accelerating unit that generates an accelerating force on the vehicle, and outputs a predetermined electric signal corresponding to the amount of depression (stepping force) to the ECU 3.

  The ECU 3 controls the overall operation of the vehicle including various configurations inside and outside the engine 2. The ECU 3 includes a processor, a memory, and the like that perform various processes. The memory is configured by a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) according to the application. The memory stores a control program for controlling the various configurations described above.

  For example, the ECU 3 determines the state of the vehicle from various sensors provided in the vehicle, and controls driving of the spark plug 26, the fuel injection valve 14, the throttle valve 12, and the like. In particular, the ECU 3 controls fuel injection and fuel cut based on accelerator on / off. For example, the ECU 3 reduces the fuel injection amount when the accelerator pedal 48 is released. Although details will be described later, the ECU 3 controls the first fuel injection valve 14a and the second fuel injection valve 14b independently to increase or decrease the respective fuel injection amounts.

  By the way, in the fuel injection control of the engine, a so-called fuel cut is performed in which the fuel injection is stopped when the accelerator pedal is released (accelerator off). In this case, vibrations of the engine due to torque steps before and after the stop of fuel injection occur, which may be a factor that makes the passenger feel uncomfortable. For this reason, it is conceivable to reduce the fuel injection amount in advance and reduce the torque step before shifting to the fuel cut.

  However, the fuel injection valve has a minimum fuel injection amount that can inject fuel with an appropriate injection amount proportional to the driving time. Specifically, in a region smaller than the predetermined fuel injection amount with a predetermined fuel injection amount as a boundary, the fuel injection amount is not proportional to the injector drive time (non-linear region), and is a region greater than the predetermined fuel injection amount. Then, the fuel injection amount is proportional to the injector driving time (linear region).

  In the non-linear region, since the fuel injection amount is not proportional to the injector driving time, it is difficult to appropriately control the fuel injection amount with the injector driving time. On the other hand, in the linear region, since the fuel injection amount is proportional to the injector drive time, the ECU can appropriately control the fuel injection amount by adjusting the injector drive time. The above-mentioned minimum fuel injection amount represents a predetermined fuel injection amount indicating a boundary between the nonlinear region and the linear region. This minimum fuel injection amount represents the minimum value of the fuel injection amount that can be controlled by the ECU by adjusting the injector drive time.

  That is, if the injector drive time is too short, the fuel injection amount is not stable. Thus, there is a possibility that an appropriate amount of fuel may not be injected in the nonlinear region where the injector drive time is extremely short. Therefore, as described above, when the driver continues to depress the accelerator pedal slightly (a minute accelerator opening), even if the required fuel injection amount falls below the minimum fuel injection amount, Fuel injection is performed with the injection amount.

  As described above, a phenomenon in which the required fuel injection amount falls below the minimum fuel injection amount can occur particularly when fuel injection is performed from a plurality of fuel injection valves toward one cylinder. This is because the fuel injection amount per fuel injection valve is smaller than that in the case where fuel injection is performed from a single fuel injection valve toward one cylinder. Therefore, it is conceivable to perform fuel cut early in order to prevent the required fuel injection amount from falling below the minimum fuel injection amount. However, the passenger feels the vibration of the engine due to the torque step as described above.

  Accordingly, the present inventors have conceived the present invention by paying attention to the minimum fuel injection amount of each fuel injection valve in an engine having a plurality of fuel injection valves per cylinder. Specifically, in the present embodiment, when the fuel injection amount is lower than the minimum fuel injection amount, the ECU 3 stops the fuel injection by some fuel injection valves (first fuel injection valve 14a) and other fuel injection valves. The fuel injection amount is increased by the (second fuel injection valve 14b). Then, the ECU 3 subsequently reduces the fuel injection amount by the second fuel injection valve 14b, and then stops the fuel injection by the second fuel injection valve 14b.

  Conventionally, in a situation where fuel is supplied by a plurality (two) of fuel injection valves 14 toward one cylinder, when it is determined that the fuel injection amount is below the minimum fuel injection amount of the fuel injection valve 14, the process proceeds to fuel cut. Then, a torque step before and after the fuel cut occurs, which leads to the vibration of the engine 2. According to the above configuration, the fuel injection of some of the fuel injection valves (first fuel injection valve 14a) is stopped, and the fuel is supplied to a predetermined cylinder only by the other fuel injection valves (second fuel injection valve 14b). By doing so, the torque step can be reduced. As a result, it is possible to reduce the vibration of the engine 2 that accompanies the fuel cut. That is, it is possible to suppress the vibration of the engine accompanying the fuel cut after the accelerator is turned off.

  Further, when the fuel injection is performed only by the other fuel injection valve (second fuel injection valve 14b), it is preferable to reduce the fuel injection amount as the vehicle is decelerated. In this case, it is possible to make the torque step smaller in the shift to the fuel cut, and it is possible to further increase the vibration reduction effect of the engine 2.

  As described above, the engine 2 is a multi-cylinder engine, and at least two fuel injection valves 14 are provided for each cylinder. In this case, it is preferable to continue the fuel injection by the second fuel injection valve 14b after stopping the fuel injection of the first fuel injection valve 14a in each cylinder. According to this configuration, by applying the same fuel injection control to each cylinder, the combustion mode can be made equivalent in each cylinder, and unnecessary engine vibration at the time of fuel injection by only the second fuel injection valve 14b. Can be appropriately suppressed.

  Next, a fuel injection control flow according to the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart of the fuel injection control according to the present embodiment. In the flow shown below, unless otherwise specified, the subject of the operation (calculation (calculation), determination, etc.) is the ECU. It is assumed that the ECU stores in advance the minimum fuel injection amounts of the first fuel injection valve 14a and the second fuel injection valve 14b. In this case, the minimum fuel injection amounts are the same.

  As shown in FIG. 3, when the control is started, in step ST101, the ECU 3 determines whether or not the accelerator is off. The ECU 3 can determine whether or not the accelerator is turned off, for example, according to the depression amount of the accelerator pedal 48. When the accelerator is off, that is, when the depression of the accelerator pedal 48 is released (step ST101: YES), the process proceeds to step ST102. Thereafter, the ECU 3 reduces the fuel injection amount as the vehicle decelerates. On the other hand, when the accelerator is not turned off (step ST101: NO), the control ends.

  In step ST102, the ECU 3 determines whether or not the fuel injection amount is less than the minimum fuel injection amount. When the fuel injection amount is below the minimum fuel injection amount (step ST102: YES), the process proceeds to step ST103. If the fuel injection amount is greater than or equal to the minimum fuel injection amount (step ST102: NO), the control ends.

  In step ST103, the ECU 3 stops the fuel injection by the first fuel injection valve 14a and increases the fuel injection amount by the second fuel injection valve 14b. In this case, it is preferable that the increase amount of the fuel injection amount of the second fuel injection valve 14b is set to be equal to or more than the decrease amount of the first fuel injection valve 14a. Then, the process proceeds to step ST104.

  In step ST104, the ECU 3 determines whether or not the fuel injection amount of the second fuel injection valve 14b has decreased. As a factor for reducing the fuel injection amount of the second fuel injection valve 14b, for example, vehicle deceleration (including depression of the brake pedal 47) can be cited. When the fuel injection amount of the second fuel injection valve 14b decreases (step ST104: YES), the process proceeds to step ST105. When the fuel injection amount of the second fuel injection valve 14b has not decreased (step ST104: NO), the process of step ST104 is repeated.

  In step ST105, the ECU 3 stops the fuel injection by the second fuel injection valve 14b, that is, performs a fuel cut. The fuel cut shown here is to stop the fuel injection of both the first fuel injection valve 14a and the second fuel injection valve 14b. Thus, the control ends.

  Here, with reference to FIG. 4, changes with time of various parameters when the control according to the present embodiment is applied will be described. FIG. 4 is a time chart showing changes with time of various parameters in the present embodiment. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates the accelerator opening, the charging efficiency, the fuel injection amount of the second fuel injection valve, the fuel injection amount of the first fuel injection valve, the torque, and the fuel cut on / off in order from the top. Is shown. Note that the time chart shown in FIG. 4 is merely an example, and is not limited thereto, and can be changed as appropriate. Moreover, in FIG. 4, the continuous line shows this Embodiment and the dashed-dotted line has shown the prior art example. In particular, the alternate long and short dash line indicated by the fuel injection amounts of the first and second fuel injection valves indicates the minimum fuel injection amount.

  As shown in FIG. 4, in a situation where the vehicle is traveling at a certain accelerator opening, when the accelerator is turned off at the timing T1, that is, when the accelerator pedal 48 is released, the fuel injection amount of each fuel injection valve. Is reduced as the vehicle decelerates, and the charging efficiency and torque gradually decrease. At this time, fuel injection is continued in both the first fuel injection valve 14a and the second fuel injection valve 14b. It is assumed that the accelerator pedal 48 is not depressed after T1.

  When the fuel injection amount of the first fuel injection valve 14a and the second fuel injection valve 14b falls below the minimum fuel injection amount at the timing of T2 thereafter, the fuel injection by the first fuel injection valve 14a is stopped (fuel injection amount). On the other hand, the fuel injection amount by the second fuel injection valve 14b is increased. Note that the increase in the fuel injection amount at this time is preferably set to be equal to or more than the decrease in the first fuel injection valve 14a. When the increase amount of the second fuel injection valve 14b is the same as the decrease amount of the first fuel injection valve 14a, the total amount of fuel injection by the two fuel injection valves so far does not change, so torque fluctuation does not occur.

  After T2, fuel injection is continued only by the second fuel injection valve 14b, and the fuel injection amount is reduced as the vehicle speed decreases. When the fuel injection amount of the second fuel injection valve 14b falls below the minimum fuel injection amount at the timing of T3, the fuel injection by the second fuel injection valve 14b is also stopped and the fuel cut is turned on.

  Between T2 and T3, the torque gradually decreases as the fuel injection amount of the second fuel injection valve 14b is reduced. For this reason, when shifting to the fuel cut at the timing of T3, the torque fluctuation before and after that becomes relatively small, and the vibration of the engine 2 can be suppressed.

  Here, returning to the timing of T2, a conventional example will be described. In the conventional example, as shown by the one-dot chain line in FIG. 2, when the fuel injection amount of the first fuel injection valve 14a and the second fuel injection valve 14b falls below the minimum fuel injection amount at the timing of T2, the minimum fuel injection is thereafter performed. Fuel injection in quantity continues. After fuel injection is continued from both the first fuel injection valve 14a and the second fuel injection valve 14b at a fixed minimum fuel injection amount, when fuel cut is turned on at the timing T3, fuel injection by both fuel injection valves Are stopped at the same time, so the torque drops sharply. That is, the torque step before and after the fuel cut transition becomes large. This is a phenomenon that may occur because the fuel injection by both fuel injection valves is continued for a predetermined time with the minimum fuel injection amount, and the fuel is supplied more than necessary.

  On the other hand, in the present embodiment, the fuel injection by the first fuel injection valve 14a is stopped at the timing of T2 as described above, while the fuel injection amount of the second fuel injection valve 14b is increased by that amount. The total fuel injection amount by both the fuel injection valves between T2 and T3 can be reduced as compared with the conventional example. For this reason, it is possible to minimize the torque step generated when shifting to the fuel cut at the timing of T3 and suppress the vibration of the engine 2.

  As described above, in the present embodiment, when the fuel injection amount is lower than the minimum fuel injection amount, the stop of the fuel injection by the first fuel injection valve 14a and the increase of the fuel injection amount by the second fuel injection valve 14b are performed. After that, after reducing the fuel injection amount by the second fuel injection valve 14b, the fuel injection by the second fuel injection valve 14b is stopped, thereby suppressing the vibration of the engine due to the fuel cut after the accelerator is turned off. Is possible.

  Next, a modified example will be described with reference to FIG. FIG. 5 is a flowchart of fuel injection control according to the modification. The modification shown in FIG. 5 is different only in that the process of step ST106 is performed between step ST104 and step ST105 of the flow shown in FIG. For this reason, it demonstrates centering on difference and it abbreviate | omits a common part suitably.

  As shown in FIG. 5, when the fuel injection amount of the second fuel injection valve 14b decreases in step ST104, the process proceeds to step ST106. In step ST106, the ECU 3 determines whether or not the fuel injection amount of the second fuel injection valve 14b is less than the minimum fuel injection amount. When the fuel injection amount of the second fuel injection valve 14b is less than the minimum fuel injection amount (step ST106: YES), the process proceeds to step ST105. When the fuel injection amount of the second fuel injection valve 14b is greater than or equal to the minimum fuel injection amount (step ST106: NO), the process of step ST106 is repeated.

  In the modification shown in FIG. 5, when the fuel injection amount of the second fuel injection valve 14b is less than the minimum fuel injection amount, the ECU 3 stops the fuel injection by the second fuel injection valve 14b, that is, performs fuel cut. . In this case, the torque of the engine 2 before the shift to the fuel cut can be reduced, and the torque step before and after the shift to the fuel cut can be reduced.

  In the above embodiment, the port injection type engine 2 has been described as an example, but the present invention is not limited to this configuration. For example, the direct injection engine 2 may be used.

  Moreover, although the said embodiment demonstrated the gasoline engine as an example, it is not limited to this. This control can be applied even to a diesel engine.

  In the above embodiment, the DOHC engine has been described as an example, but the present invention is not limited to this. The engine 2 may be an SOHC (Single OverHead Camshaft) engine.

  In the above embodiment, after T2, the fuel injection amount of the second fuel injection valve 14b is gradually decreased as the vehicle decelerates, and the fuel cut is performed when the fuel injection amount falls below the minimum fuel injection amount. However, the present invention is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the fuel injection amount of the 2nd fuel injection valve 14b was increased simultaneously with stopping the fuel injection by the 1st fuel injection valve 14a at the timing of T2, it is not limited to this. For example, the modification shown in FIG. 6 is also possible. 6A and 6B are time charts showing a change with time of the fuel injection amount according to another modification. In FIG. 6, when the fuel injection by the first fuel injection valve 14a is stopped at the timing of T2, the rate of decrease of the fuel injection amount by the second fuel injection valve 14b at the timing of T4 before T2 (change in decrease with time) The control is performed (started) so that the rate) is equal to or less than the weight loss rate before T4.

  Specifically, in FIG. 6A, after T1, at the timing of T4 before T2, the fuel injection amount by the second fuel injection valve 14b is maintained and the fuel injection by the second fuel injection valve 14b is performed until the timing of T2. continue. Thus, in anticipation of stopping the fuel injection by the first fuel injection valve 14a at the timing of T2, by increasing the fuel injection amount by the second fuel injection valve 14b in advance, the torque fluctuation at the timing of T2 can be reduced. It is possible to suppress as much as possible.

  Further, the fuel injection amount is gradually decreased between T4 and T2 as shown in FIG. 6B, not only in the case where fuel injection is continued at a constant fuel injection amount between T4 and T2 as shown in FIG. 6A. May be. In this case, the reduction rate of the fuel injection amount between T4 and T2 (amount of change in reduction with time) is set smaller than that in FIG. 6A, and the reduction rate of the fuel injection amount between T2 and T3 is as shown in FIG. 4 and FIG. Is preferably set to be small. For example, the total fuel injection amount of the second fuel injection valve 14b between T2 and T3 in FIG. 4 is the same as the total fuel injection amount of the second fuel injection valve 14b between T4 and T3 in FIG. 6B. You may set the said weight reduction rate so that it may become.

  In the above embodiment, the case where the first fuel injection valve 14a and the second fuel injection valve 14b have the same performance (the same minimum fuel injection amount) has been described. However, the present invention is not limited thereto. Not. For example, the plurality of fuel injection valves may have different minimum fuel injection amounts. In this case, it is preferable to apply the above control so that the fuel injection valve having the larger minimum fuel injection amount is preferentially stopped.

  Moreover, although this Embodiment and the modified example were demonstrated, what combined the said embodiment and modified example entirely or partially as another embodiment of this invention may be sufficient.

  The embodiments of the present invention are not limited to the above-described embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by technological advancement or other derived technology, the method may be used. Accordingly, the claims cover all embodiments that can be included within the scope of the technical idea of the present invention.

  As described above, the present invention has the effect of suppressing the vibration of the engine accompanying the fuel cut after the accelerator is turned off in an engine having a plurality of fuel injection valves per cylinder. This is useful for a fuel injection control device applied to an injection type engine.

1: Control system 2: Engine 3: ECU
10: Intake pipe 11: Air cleaner 12: Throttle valve 13: Surge tank 14: Fuel injection valve 14a: First fuel injection valve 14b: Second fuel injection valve 15: Exhaust pipe 16: Catalyst 20: Crankshaft 21: Cylinder 21a: Bore space 22: Cylinder head 23: Piston 24: Connecting rod 25: Combustion chamber 26: Spark plug 27a: Intake port 27b: Exhaust port 28a: Intake valve 28b: Exhaust valve 29a: Intake camshaft 29b: Exhaust camshaft 40: Air volume Sensor 41: Intake pressure sensor 42: Air-fuel ratio sensor 43: Air-fuel ratio sensor 44: Water temperature sensor 45: Crank sensor 46: Vehicle speed sensor 47: Brake pedal 48: Accelerator pedal

Claims (5)

A fuel injection control device for reducing a fuel injection amount associated with release of depression of an accelerator pedal in an engine including at least two fuel injection valves per cylinder,
When the fuel injection amount is lower than the minimum fuel injection amount, the fuel injection is stopped by some fuel injection valves and the fuel injection amount is increased by other fuel injection valves, and then the other fuel injection valves After the fuel injection amount is reduced, fuel injection control by the other fuel injection valve is stopped.   2. The fuel injection control device according to claim 1, wherein when the fuel injection is performed only by the other fuel injection valve, the fuel injection amount is decreased as the vehicle decelerates.   3. The fuel injection control according to claim 1, wherein when the fuel injection amount of the other fuel injection valve is lower than the minimum fuel injection amount, fuel injection by the other fuel injection valve is stopped. apparatus. The engine is a multi-cylinder engine;
The at least two fuel injection valves are provided for each cylinder;
The fuel according to any one of claims 1 to 3, wherein the fuel injection by the other fuel injection valves is continued after the fuel injection of the partial fuel injection valves in each cylinder is stopped. Injection control device.   The reduction rate of the fuel injection amount by the other fuel injection valves is made equal to or less than the previous reduction rate at a timing prior to the stop of the fuel injection by the partial fuel injection valves. The fuel injection control device according to any one of claims 1 to 4.

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