JP2019206943A - Fuel injection control device - Google Patents

Abstract

To suppress deterioration of fuel economy and emission, in a fuel injection system in which a plurality of fuel injection valves are provided to one cylinder.SOLUTION: A fuel injection system comprises: a plurality of fuel injection valves 20 which are provided while being made to correspond to respective intake ports 18, respectively, in an engine 10 in which a plurality of the intake ports 18 are provided to one cylinder; and an injector drive circuit for driving the respective fuel injection valves 20 by energization to the plurality of fuel injection valves 20. When fuel injection is performed by the respective fuel injection valves 20 in one combustion cycle of the engine 10, respectively, a microcomputer of an ECU 40 sets a power supply voltage of the injector drive circuit on the basis of injection times of the respective fuel injection valves 20, and makes the injector drive circuit drive the respective fuel injection valves 20 by the set power supply voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection control device applied to a fuel injection system in which a plurality of fuel injection valves are provided for one cylinder.

  Conventionally, in an internal combustion engine in which a plurality of intake ports are provided for one cylinder, a dual injection system in which a fuel injection valve is provided corresponding to each of the plurality of intake ports has been proposed (for example, see Patent Document 1). In such a system, each fuel injection valve is arranged to inject fuel toward the respective intake port.

  In the dual injection system, the amount of fuel injected per time by the fuel injection valve is reduced as compared with a configuration in which only one fuel injection valve is provided for a plurality of intake ports. Therefore, it is possible to suppress the so-called fuel wet that fuel injected from the fuel injection valve adheres to the wall surface forming the intake port. In addition, since most of the fuel injected from the fuel injection valve is introduced into the cylinder and vaporized without adhering to the wall surface, the in-cylinder temperature is reduced by the heat of vaporization, improving the air filling rate and suppressing knocking. Etc. can also be obtained.

JP 2007-26295 A

  By the way, in the above-described dual injection system, the fuel per cylinder is divided and injected by a plurality of fuel injection valves, so it is conceivable that the fuel injection time at each fuel injection valve is shortened. Here, the particle size of the fuel injected from the fuel injection valve tends to increase immediately after the fuel injection valve is opened. For this reason, in the dual injection system in which the fuel injection time by the fuel injection valve is shortened, there is a concern that the influence of the particle size increase immediately after the valve opening becomes large, leading to deterioration of fuel consumption and emission. In particular, in the dual injection system, the particle size increases in each of the plurality of fuel injection valves, so that there is a risk that the fuel consumption will deteriorate significantly.

  The present invention has been made in view of the above circumstances, and in a fuel injection system in which a plurality of fuel injection valves are provided for one cylinder, fuel injection control capable of suppressing deterioration in fuel consumption and emission. The main purpose is to provide a device.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  A fuel injection control device according to the present invention includes a plurality of fuel injection valves provided corresponding to each of the intake ports in an internal combustion engine provided with a plurality of intake ports for one cylinder, and the plurality of fuel injection valves. When each of the fuel injection valves performs fuel injection in one combustion cycle of the internal combustion engine, the fuel injection system includes: Based on the injection time of the fuel injection valve, a voltage setting unit that sets a power supply voltage of the drive circuit, and the power supply voltage set by the voltage setting unit causes the fuel injection valve to be driven by the drive circuit And a drive control unit.

  According to the above configuration, in the fuel injection system in which a plurality of fuel injection valves are provided for one cylinder, when each fuel injection valve performs fuel injection during one combustion cycle, each fuel injection valve The power supply voltage of the drive circuit is variably set according to the injection time. Accordingly, when fuel injection is performed by each fuel injection valve, that is, when fuel is divided and injected by each fuel injection valve, each fuel injection is performed while taking into account that the injection time of each fuel injection valve is shortened. The valve can be driven. That is, at the beginning of the opening of the fuel injection valve, it is considered that the particle size of the fuel spray varies depending on the power supply voltage. In this case, by setting the power supply voltage to a high voltage, the dead time until each fuel injection valve is opened is shortened, and the increase in particle size immediately after the valve is opened is suppressed. As a result, in a fuel injection system in which a plurality of fuel injection valves are provided for one cylinder, it is possible to suppress deterioration in fuel consumption and emission.

The figure which shows schematic structure of a fuel-injection system. The schematic diagram which shows the arrangement | positioning state of a fuel injection valve. The block diagram which shows the structure of ECU. The figure which shows the relationship between the fuel particle size after the valve opening of a fuel injection valve, and the injection period. The flowchart which shows a fuel-injection control process. (A) is a figure which shows the relationship between injection time and pressure | voltage rise amount, (b) is a figure which shows the relationship between engine cooling water temperature and pressure | voltage rise amount, (a) shows the relationship between battery voltage and pressure | voltage rise amount. FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a fuel injection system of a port injection type engine (internal combustion engine) is embodied. FIG. 1 is a diagram showing a schematic configuration of a fuel injection system.

  As shown in FIG. 1, in the engine 10, a throttle valve 13 is provided in the intake pipe 11. The throttle valve 13 is adjusted in opening by a motor 14. A surge tank 16 is provided downstream of the throttle valve 13 in the intake pipe 11, and an intake manifold 17 is connected to the surge tank 16.

  The intake manifold 17 is connected to an intake port 18 of each cylinder. The intake port 18 is formed in the cylinder head of the engine 10 and communicates with the combustion chamber 21. An exhaust port 19 is formed in the cylinder head. The exhaust port 19 communicates with the combustion chamber 21 and is connected to the exhaust pipe 12. In the following, the end opening on the combustion chamber 21 side in the intake port 18 is also referred to as an intake port 18a.

  The intake port 18 is provided with an intake valve 23, and the exhaust port 19 is provided with an exhaust valve 24. When the intake valve 23 is opened, the air in the intake pipe 11 is introduced into the combustion chamber 21 via the intake port 18. When the exhaust valve 24 is opened, the exhaust gas after combustion is discharged to the exhaust pipe 12 through the exhaust port 19.

  The engine 10 includes an electromagnetically driven fuel injection valve 20 that supplies fuel to each cylinder. The engine 10 employs a port injection type in which fuel is injected from the fuel injection valve 20 toward the intake port 18, and the fuel injection valve 20 is provided in the vicinity of the intake port 18 of each cylinder. Hereinafter, the arrangement of the fuel injection valve 20 will be described with reference to FIG. FIG. 2 is a schematic diagram showing an arrangement state of the fuel injection valve 20. In FIG. 2, illustration of the intake valve 23 and the exhaust valve 24 is omitted for convenience.

  As shown in FIG. 2, in this engine 10, two intake ports 18 are provided for each cylinder. Each intake port 18 communicates with an intake manifold 17 and also with a combustion chamber 21. Similarly to the intake port 18, two exhaust ports 19 are provided for each cylinder. Each of the exhaust ports 19 communicates with the combustion chamber 21 and also with the exhaust pipe 12.

  In the intake manifold 17, a fuel injection valve 20 is provided in the vicinity of the intake port 18. Two fuel injection valves 20 are provided corresponding to each intake port 18. Accordingly, the engine 10 employs a dual injection system in which two fuel injection valves 20 (20A, 20B) are provided for one cylinder. Each of the fuel injection valves 20A and 20B is arranged in a direction in which fuel is injected toward the intake port 18a of the intake port 18. For this reason, when fuel is injected by the fuel injection valves 20A and 20B when the intake valve 23 is opened, the injected fuel flows directly into the combustion chamber 21 via the intake port 18a.

  Returning to the description of FIG. 1, the fuel injection valve 20 is connected to a fuel tank 27 via a fuel pipe 26. The fuel tank 27 is filled with fuel. The fuel in the fuel tank 27 is pumped up by the pump 28 and supplied to the fuel injection valve 20 of each cylinder.

  A spark plug 31 is attached to the cylinder head of the engine 10 for each cylinder. This spark discharge by the spark plug 31 ignites the air-fuel mixture in the combustion chamber 21.

  The exhaust pipe 12 is provided with an oxygen concentration sensor 32 that detects the oxygen concentration in the exhaust gas. In the exhaust pipe 12, a catalyst 33 such as a three-way catalyst for purifying exhaust gas is provided on the downstream side of the oxygen concentration sensor 32.

  In addition, the engine 10 outputs a coolant temperature sensor 35 that detects the coolant temperature, a load sensor 36 that detects an engine load such as an intake air amount and intake pipe negative pressure, and a rectangular signal for each predetermined crank angle of the engine. A crank angle sensor 37 and the like are provided. Further, the engine speed is detected based on the output signal of the crank angle sensor 37.

  As is well known, the ECU 40 is mainly composed of a microcomputer composed of a CPU, ROM, RAM, and the like, and executes various control programs stored in the ROM, so that various controls of the engine 10 are performed according to the engine operating state each time. To implement. That is, the ECU 40 receives detection signals from the various sensors described above, calculates the fuel injection amount, ignition timing, and the like based on the various detection signals, and based on the calculation results, the fuel injection valve 20 and the ignition device. Control the drive.

  FIG. 3 is a block diagram showing the configuration of the ECU 40. As shown in FIG. 3, the ECU 40 includes a microcomputer 41 (microcomputer) for engine control and an injector drive circuit 42 for driving the fuel injection valve 20. The microcomputer 41 determines the fuel injection amount per cylinder required in one combustion cycle (intake stroke → compression stroke → expansion stroke → exhaust stroke) of the engine 10 according to the engine operating state (engine load, engine speed, etc.). Calculated as the required injection amount Q. Then, the microcomputer 41 divides the calculated required injection amount Q into the required injection amount Qa of the fuel injection valve 20A and the required injection amount Qb of the fuel injection valve 20B (Q = Qa + Qb).

  The microcomputer 41 calculates the injection time Ta of the fuel injection valve 20A according to the required injection amount Qa of the fuel injection valve 20A, and the injection time of the fuel injection valve 20B according to the required injection amount Qb of the fuel injection valve 20B. Tb is calculated. The injection times Ta and Tb are the time lengths of the injection pulses. Then, the microcomputer 41 outputs an injection pulse generated based on the calculated injection times Ta and Tb of the fuel injection valves 20A and 20B to the injector drive circuit 42. The injector drive circuit 42 opens and drives the fuel injection valve 20A by the injection pulse of the fuel injection valve 20A, and opens the fuel injection valve 20B by the injection pulse of the fuel injection valve 20B. Thereby, the fuel for the required injection amount Qa is injected by the fuel injection valve 20A, and the fuel for the required injection amount Qb is injected by the fuel injection valve 20B.

  The microcomputer 41 corresponds to a “fuel injection control device”, and the injector drive circuit 42 corresponds to a “drive circuit”.

  A battery 45 is connected to the injector drive circuit 42. The injector drive circuit 42 includes a booster circuit 43 that boosts the voltage (battery voltage) supplied from the battery 45 to a voltage higher than the battery voltage. In the booster circuit 43, the battery voltage can be boosted continuously and continuously. In this embodiment, the battery voltage is rated at 12 V, and the battery voltage can be continuously boosted to 40 V by the booster circuit 43.

  The injector drive circuit 42 energizes the fuel injectors 20A and 20B (specifically, the coils of the fuel injectors 20A and 20B) by applying the voltage boosted by the booster circuit 43 to the fuel injectors 20A and 20B. Then, by energization, the fuel injection valves 20A and 20B are driven to open.

  The microcomputer 41 has a setting function for variably setting the boost amount ΔV by the booster circuit 43 (for example, the boost amount ΔV with respect to the battery voltage Vo). The microcomputer 41 causes the boosting circuit 43 to perform boosting with the set boosting amount ΔV. Thus, the boosted voltage V is applied to each fuel injection valve 20A, 20B by the injector drive circuit 42, and each fuel injection valve 20A, 20B is driven to open (V = Vo + ΔV). That is, the voltage V boosted by the booster circuit 43 is a drive voltage for the fuel injectors 20A and 20B, in other words, a power supply voltage for the injector drive circuit 42. The boosted voltage V corresponds to the “power supply voltage of the drive circuit”.

  The voltage of the battery 45 is detected by the voltage sensor 46. Detection signals from the voltage sensor 46 are sequentially input to the ECU 40.

  By the way, when the fuel injection is performed by each of the two fuel injection valves 20A and 20B, the injection time per one time becomes shorter than that when the fuel injection is performed by one fuel injection valve. As a result, there is a concern that the spray particle size increases and inconveniences such as deterioration of exhaust emission occur. FIG. 4 is a diagram showing the relationship between the fuel particle size and the injection period after the fuel injection valve 20 is opened. According to FIG. 4, immediately after the fuel injection valve 20 is opened, that is, when the injection time is short. It can be confirmed that the fuel particle size is increased. Therefore, in the present embodiment, the power supply voltage of the injector drive circuit 42 is variably set based on the injection time of each fuel injection valve 20A, 20B, and each fuel injection valve 20A, 20B by the injector drive circuit 42 is set based on the power supply voltage. It is supposed to be driven.

  Next, the fuel injection control process executed by the microcomputer 41 of the ECU 40 will be described based on the flowchart shown in FIG. This process is repeatedly executed at a predetermined cycle.

  As shown in FIG. 5, first, in step S11, a required injection amount Q per cylinder is calculated based on the engine operating state. In the subsequent step S12, the required injection amount Q is divided into the required injection amounts Qa and Qb of the fuel injection valves 20A and 20B. In this case, the required injection amount Q is divided so that the required injection amount Qa of the fuel injection valve 20A and the required injection amount Qb of the fuel injection valve 20B become the same amount (Qa = Qb).

  In step S13, the injection times Ta and Tb of the fuel injection valves 20A and 20B are calculated based on the required injection amounts Qa and Qb of the fuel injection valves 20A and 20B. In this case, the injection times Ta and Tb of the fuel injection valves 20A and 20B are calculated with the same time (Ta = Tb).

  In step S14, the boost amount ΔV in the booster circuit 43 is set based on the injection times Ta and Tb of the fuel injectors 20A and 20B. In the present embodiment, the relationship between the injection times Ta and Tb and the pressure increase amount Δ is stored in advance in the ROM as a map, and the pressure increase amount Δ is set using the map. FIG. 6 (a) shows an example of such a map. According to FIG. 6 (a), the pressure increase amount Δ is set to a larger value as the injection time is shorter. Thereby, the drive voltage applied to each fuel injection valve 20A, 20B, in other words, the power supply voltage V of the injector drive circuit 42 is variably set.

  Thereafter, in step S15, the engine coolant temperature detected by the coolant temperature sensor 35 and the battery voltage detected by the voltage sensor 46 are acquired. In the subsequent step S16, the boost amount ΔV is corrected based on the engine coolant temperature and the battery voltage. In this case, the relationship shown in FIG. 6B is defined as the relationship between the engine coolant temperature and the pressure increase ΔV, and the relationship is used to correct the pressure increase ΔV based on the engine coolant temperature. According to FIG. 6B, the pressure increase amount ΔV is set to a larger value as the engine coolant temperature is lower. The relationship in FIG. 6B may be stored in advance in the ROM as a map.

  Further, the battery voltage has a correlation with the remaining capacity (SOC) of the battery 45. Specifically, there is a relationship that the battery voltage decreases as the remaining capacity of the battery 45 decreases. For this reason, in step S16, the boost amount ΔV is corrected based on the remaining capacity of the battery 45 by correcting the boost amount ΔV based on the battery voltage. In this case, the relationship shown in FIG. 6C is defined as the relationship between the battery voltage and the boost amount ΔV, and the boost amount ΔV is corrected based on the battery voltage using the relationship. According to FIG. 6C, the lower the battery voltage, in other words, the smaller the remaining capacity of the battery 45, the smaller the boost amount ΔV is set. The relationship shown in FIG. 6C is preferably stored in advance in the ROM as a map. Note that the processing in steps S14 to S16 corresponds to processing as a “voltage setting unit”.

  In subsequent step S17, the booster circuit 43 boosts the battery voltage Vo based on the boost amount ΔV.

  Thereafter, in step S18, the fuel injection valves 20A and 20B are driven to open by the injection pulses generated based on the injection times Ta and Tb of the fuel injection valves 20A and 20B. At this time, the boosted power supply voltage V (drive voltage) is applied to the fuel injection valves 20A and 20B by the injector drive circuit 42, and the fuel injection valves 20A and 20B are driven to open. Thereby, fuel injection is performed by each fuel injection valve 20A, 20B. In this embodiment, the fuel injection valves 20A and 20B are driven to open at the same timing, and therefore, fuel injection is simultaneously performed (started) from the fuel injection valves 20A and 20B. After the completion of step S18, the control process is terminated. Note that the processing in steps S17 and S18 corresponds to processing as a “drive control unit”.

  As mentioned above, according to the structure of this embodiment explained in full detail, the following outstanding effects are acquired.

  When fuel injection is performed in each of the fuel injection valves 20A and 20B during one combustion cycle, the power supply voltage V of the injector drive circuit 42 is variably set based on the injection times Ta and Tb. According to this configuration, when fuel injection is performed by the fuel injection valves 20A and 20B, that is, when fuel is divided and injected by the fuel injection valves 20A and 20B, the fuel of the fuel injection valves 20A and 20B The fuel injection valves 20A and 20B can be driven while taking into account that the injection time is shortened. That is, at the beginning of the opening of the fuel injection valves 20A and 20B, it is conceivable that the particle size of the fuel spray varies depending on the power supply voltage V. In this case, by setting the power supply voltage V to a high voltage, the dead time until the fuel injection valves 20A and 20B are opened is shortened, and the increase in the particle size immediately after the opening is suppressed. As a result, in a fuel injection system in which a plurality of fuel injection valves 20A and 20B are provided for one cylinder, it is possible to suppress deterioration in fuel consumption and emission.

  The power supply voltage V is variably set so that the power supply voltage V becomes higher as the injection times Ta and Tb of the fuel injection valves 20A and 20B are shorter. As a result, when the injection times Ta and Tb of the fuel injection valves 20A and 20B are short, that is, when the fuel injection valves 20A and 20B are easily affected by the increase in particle size immediately after opening, the power supply voltage V of the injector drive circuit 42 is increased. The fuel injection valves 20A and 20B can be driven with a high power supply voltage V. For this reason, deterioration of fuel consumption and emission can be suitably suppressed.

  Further, when the injection times Ta and Tb are relatively long, the power supply voltage V is set lower, so that boosting is performed as necessary. For this reason, it is possible to suppress excessive consumption of the energy stored in the battery 45.

  Since the fuel is difficult to vaporize when the engine 10 is at a low temperature, problems such as deterioration in fuel consumption accompanying an increase in the particle size during fuel injection tend to occur. In that respect, in the above embodiment, the power supply voltage V of the injector drive circuit 42 is set based on the engine coolant temperature. In this case, the fuel injection valves 20A and 20B can be driven by setting the power supply voltage V of the injector drive circuit 42 high when the temperature of the engine 10 at which the fuel is difficult to vaporize is low. For this reason, even under a temperature condition in which the fuel is difficult to vaporize, it is possible to suitably suppress deterioration of fuel consumption.

  Further, the power supply voltage V of the injector drive circuit 42 is set based on the battery voltage, in other words, based on the remaining capacity of the battery 45 (remaining battery capacity). Thereby, when the battery remaining amount is low, the power supply voltage V is set low, so that it is possible to avoid a situation in which the battery remaining amount is significantly reduced.

  The present invention is not limited to the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, the boost amount ΔV by the booster circuit 43 is set using the relationships shown in FIGS. 6A to 6C. However, the boost amount Δ need not necessarily be set using these relationships. For example, when the pressure increase ΔV is set based on the injection times Ta and Tb of the fuel injection valves 20A and 20B, the pressure increase ΔV is set based on whether or not the injection times Ta and Tb are shorter than a predetermined time. Also good. Specifically, when the injection times Ta and Tb are equal to or longer than the predetermined time, the pressure increase amount ΔV is set to α (fixed value), and when the injection time Ta, Tb is shorter than the predetermined time, the pressure increase amount ΔV is set to β ( It is conceivable to set a fixed value. In this case, the power supply voltage V of the injector drive circuit 42 is set in two stages, large and small, according to the injection times Ta and Tb of the fuel injection valves 20A and 20B.

  The power supply voltage V can be variably set based on the correlation between the operating state of the engine 10 and the injection times Ta and Tb of the fuel injection valves 20A and 20B. Specifically, it is determined that the predetermined low load state including the idling operation state, and in the low load state, the power supply voltage V is set to a higher voltage than in the case where the load is higher than that. The configuration may be set.

  For example, a fuel pressure sensor that detects the pressure in the fuel pipe 26 that supplies fuel to the fuel injection valves 20A and 20B, that is, a fuel pressure, is provided, and the power supply voltage V of the injector drive circuit 42 is set based on the detection signal of the fuel pressure sensor You may make it do. In this case, it is conceivable that the power supply voltage V is set higher as the fuel pressure detected by the fuel pressure sensor is higher. When the fuel pressure is high, it is assumed that the opening times of the fuel injection valves 20A and 20B are shortened. In this case, it is considered that the fuel injection valves 20A and 20B are easily affected by the increase in the particle size immediately after the opening. In this regard, with the above configuration, when the fuel pressure is high and the valve opening time is shortened, the power supply voltage V of the injector drive circuit 42 is set high and the valve opening time is shortened. It becomes possible.

  In the above embodiment, the power supply voltage V of the injector drive circuit 42 is set based on the engine coolant temperature. For example, the power supply voltage V is based on the intake air temperature detected by the intake air temperature sensor (corresponding to the temperature sensor). May be set. Since the intake air temperature is the temperature in the engine 10, in this case as well, it is possible to obtain an effect of suitably suppressing deterioration of fuel consumption and the like by setting the power supply voltage V high when the engine temperature is low, where the fuel is difficult to vaporize. .

  Instead of the intake air temperature sensor, an outside air temperature sensor (corresponding to a temperature sensor) may be used. Since the intake air temperature depends on the outside air temperature, the intake air temperature (and hence the engine temperature) can be indirectly detected in this case as well. The engine coolant temperature, the intake air temperature, and the outside air temperature all correspond to the temperature information of the engine 10.

  In the above embodiment, when the required injection amount Q is divided into the required injection amounts Qa and Qb of the fuel injection valves 20A and 20B, the required injection amounts Qa and Qb are divided so as to be the same amount (that is, Qa = Qb), this may be changed and divided so that the required injection amounts Qa and Qb are different amounts (Qa <Qb or Qa> Qb). In this case, it is conceivable to set the power supply voltage V of the injector drive circuit 42 based on the injection time calculated based on the required injection amount on the smaller side of the required injection amounts Qa and Qb.

  In the above embodiment, the fuel injection is performed simultaneously by the fuel injection valves 20A and 20B. For example, the fuel injection is first performed from one fuel injection valve 20A among the fuel injection valves 20A and 20B, and then the other fuel injection valve 20A and 20B. A case where fuel is injected from the fuel injection valve 20B is also conceivable. Therefore, the present invention may be applied in such a case. In short, the present invention can be applied if fuel injection is performed by each of the fuel injection valves 20A and 20B in one combustion cycle.

  The injector drive circuit 42 may be provided outside the ECU 40. For example, it is conceivable to provide the injector drive circuit 42 in the fuel injection valve 20 (for example, a control device for the fuel injection valve 20). Similarly, the booster circuit 43 may be provided outside the ECU 40.

  In the above embodiment, the present invention is applied to a fuel injection system (dual injection system) in which two fuel injection valves 20 are provided for one cylinder, but three fuel injection valves 20 are provided for one cylinder. The present invention may be applied to a fuel injection system provided. That is, the present invention may be applied to a system in which three intake ports 18 are provided for one cylinder, and fuel injection valves 20 are provided in the respective intake ports 18. Further, the present invention may be applied to a system in which four or more fuel injection valves 20 are provided for one cylinder.

  DESCRIPTION OF SYMBOLS 10 ... Engine (internal combustion engine), 18 ... Intake port, 20 ... Fuel injection valve, 40 ... ECU, 41 ... Microcomputer (voltage setting part, drive control part), 42 ... Injector drive circuit.

Claims (4)

A plurality of fuel injection valves (20) provided corresponding to each of the intake ports in an internal combustion engine (10) provided with a plurality of intake ports (18) for one cylinder;
A drive circuit (42) for driving each of the fuel injection valves by energization of the plurality of fuel injection valves, and a fuel injection system comprising:
A voltage setting unit that sets a power supply voltage of the drive circuit based on an injection time of each fuel injection valve when fuel injection is performed by each of the fuel injection valves in one combustion cycle of the internal combustion engine;
A drive control unit for driving each fuel injection valve by the drive circuit with the power supply voltage set by the voltage setting unit;
A fuel injection control device (41).   The fuel injection control device according to claim 1, wherein the voltage setting unit variably sets the power supply voltage so that the power supply voltage becomes higher as the injection time is shorter. A temperature acquisition unit for acquiring temperature information of the internal combustion engine;
The fuel injection control device according to claim 1, wherein the voltage setting unit sets the power supply voltage based on temperature information acquired by the temperature acquisition unit. The drive circuit can generate the power supply voltage higher than the battery voltage by boosting the voltage of the battery (45),
The fuel injection control device according to any one of claims 1 to 3, wherein the voltage setting unit sets the power supply voltage based on a remaining capacity of the battery.

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