JP2008101478A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device in which the low accuracy of fuel injection amount is quickly eliminated. <P>SOLUTION: In a priority learning cylinder setting treatment S110, a cylinder in which the difference between an actual injection amount and an instruction injection amount is large is set as a priority learning cylinder for which a corrected injection amount must be preferentially calculated (injection amount learning). In an injection correction amount calculating treatment S120, a single injection is performed for the set priority learning cylinder to acquire a predetermined quantity of learned values. Based on the acquired learned values, a corrected injection amount is obtained. This is repeated until the injection correction amount calculating treatment is performed for all the cylinders S130. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection control device that controls fuel injection in an internal combustion engine having multiple cylinders.

  Conventionally, in an internal combustion engine such as a gasoline engine or a diesel engine, the difference between the command injection amount for the injector and the actual injection amount is acquired as a learned value, and the actual injection amount matches the command injection amount based on the acquired learned value. 2. Description of the Related Art There is known a fuel injection control device that obtains an injection correction amount for causing an injector to drive an injector according to a command injection amount corrected by the injection correction amount (see, for example, Patent Documents 1 and 2).

  In these conventional apparatuses described in Patent Documents 1 and 2, fuel is supplied only to the injector of a specific cylinder of the internal combustion engine when the command injection amount to the injector is zero or less (for example, at the time of shift change or deceleration). The injection (hereinafter referred to as “single injection”) is performed, and the actual injection amount is estimated from the fluctuation amount of the engine speed generated by the single injection.

FIG. 7 is a schematic diagram showing changes in the engine speed ω [rpm] when single injection is performed when the engine is not loaded. However, the points in the figure are the injection timings of the respective cylinders, and the figure shows the case where the single injection is performed at the injection timing of the cylinder # 1.
JP 2005-133678 A JP 2005-139951 A

  By the way, in an internal combustion engine having multiple cylinders, the fuel injection amount of each cylinder varies from cylinder to cylinder due to the influence of the characteristics of the individual injectors, and even the same cylinder is influenced by the operating environment. Variations occur from time to time. For this reason, the above-described injection amount learning not only needs to be performed individually for each cylinder, but also reduces variation such as collecting a plurality of learning data for each cylinder and averaging the collected learning data. It is necessary to take measures. Therefore, a lot of learning data must be collected in the injection amount learning.

  In particular, in order to mitigate the influence of the operating environment, learning should be collected when determining the injection correction amount for each operating environment (for example, the magnitude of the common rail pressure for a diesel engine) even in the same cylinder. Data further increases.

  Further, in the conventional devices described in Patent Documents 1 and 2, when the learning condition is satisfied, the cylinder at the injection timing immediately after that becomes the specific cylinder. That is, the specific cylinder that performs the single injection is stochastically determined by the course of operation, and learning data for all the cylinders is collected in parallel.

  As a result, it takes a long time to collect all of the learning data necessary for calculating the injection correction amount. During this time, the deviation between the command injection amount and the actual injection amount is large, that is, the injection amount accuracy is high. There was a problem that the low state continued.

  In order to solve the above-described problems, an object of the present invention is to provide a fuel injection control device capable of quickly eliminating a state where the accuracy of the injection amount is low.

  In the fuel injection control device of the present invention made to achieve the above object, the command injection amount setting means sets a command injection amount that is a fuel amount to be injected into an injector provided in each cylinder of an internal combustion engine having multiple cylinders. The correction unit corrects the command injection amount using a previously obtained injection correction amount, and the drive unit drives the injector according to the corrected command injection amount.

  Further, the correction amount calculation means performs a single injection that causes the injector of any one cylinder of the internal combustion engine to perform fuel injection during a learning period in which a preset learning condition is satisfied, and performs this single injection The actual injection amount that is the fuel amount actually injected by the injector or the actual injection correlation amount that has a correlation with the actual injection amount is acquired as a learning value based on the fluctuation in the rotational speed of the internal combustion engine. Based on this, the above-described injection correction amount is calculated.

  In particular, in the present invention, the priority learning cylinder setting means determines the difference between the command injection amount and the actual injection amount for each cylinder, sets the cylinder having the largest difference as the priority learning cylinder, and the correction amount calculation means The learning value is acquired for the set priority learning cylinder.

  Therefore, according to the fuel injection control device of the present invention, when the priority learning cylinder is set, the learning value is acquired intensively for the priority learning cylinder, so that it is necessary to calculate the injection correction amount of the priority learning cylinder. The time required to acquire a large number of learning values, and thus the time required for the learning result (injection correction amount) to be reflected in the fuel injection control, is significantly larger than that of a conventional device that does not set a priority learning cylinder. Can be shortened.

  In addition, according to the fuel injection control device of the present invention, learning is performed in order from the cylinder with the largest determination value, that is, the cylinder with the lowest accuracy of the injection amount, and each time learning for one cylinder is completed. Therefore, the accuracy of the average injection amount for all the cylinders can be quickly improved.

  In the fuel injection control device of the present invention, the priority learning cylinder setting means, for example, as described in claim 2, performs single injection once for all the cylinders for which the injection correction amount needs to be calculated. The determination value (difference between the command injection amount and the actual injection amount) may be obtained from the result.

  In other words, it is not possible to obtain a highly accurate determination value from the result of one single injection, but it is possible to set a priority learning cylinder as long as it is possible to determine the magnitude relationship between the determination values among the cylinders. It is not always necessary to obtain the determination value with accuracy as in the case of obtaining the correction amount.

  Further, in the fuel injection control device of the present invention, the priority learning cylinder setting means is configured to perform a single injection for a required number of times within one learning period, as described in claim 3. It is desirable.

  That is, the result of the single injection changes depending on the usage environment (fuel pressure, ambient temperature, etc.) at that time even in the same cylinder. However, since it is unlikely that the operating environment will change significantly during a single learning period, the cylinders that should be prioritized are more accurate than when single injection is performed for all cylinders over multiple learning periods. Can be specified.

  Further, in the fuel injection control device of the present invention, the correction amount calculation means uses at least a command injection amount as zero or less as a learning condition as described in claim 4, or according to claim 5. As described, it is desirable that the learning condition is that at least the command injection amount is zero or less and the transmission is in the neutral state.

  In this way, by performing single injection at the time of non-injection, it is possible to accurately detect fluctuations in the rotational speed of the internal combustion engine caused by single injection. In particular, if the transmission is in a neutral state, the rotational inertia force of the internal combustion engine (the number of revolutions when single injection is not performed) can be accurately grasped, so that fluctuations in the number of revolutions can be detected more accurately. Can do.

Embodiments of the present invention will be described below with reference to the drawings.
<Overall configuration>
FIG. 1 is an overall configuration diagram showing a fuel injection system applied to a four-cylinder diesel engine (hereinafter referred to as “engine”) 1.

  As shown in FIG. 1, the fuel injection system includes a common rail 2 that stores high-pressure fuel, a fuel supply pump 4 that pressurizes fuel pumped from a fuel tank 3 and supplies the fuel to the common rail 2, and high-pressure fuel supplied from the common rail 2. Is injected into the cylinder (combustion chamber 1a) of the engine 1 and an electronic control unit (hereinafter referred to as "ECU") 6 for electronically controlling the system.

  The common rail 2 has a target rail pressure set by the ECU 6 and accumulates the high-pressure fuel supplied from the fuel supply pump 4 to the target rail pressure. The common rail 2 includes a pressure sensor 7 that detects the accumulated fuel pressure (hereinafter referred to as rail pressure) and outputs it to the ECU 6, and a pressure limiter that limits the rail pressure so as not to exceed a preset upper limit value. 8 is attached.

  The fuel supply pump 4 includes a camshaft 9 that is driven by the engine 1 to rotate, a feed pump 10 that is driven by the camshaft 9 to pump fuel from the fuel tank 3, and a cylinder 11 in synchronization with the rotation of the camshaft 9. It has a plunger 12 that reciprocates inside and an electromagnetic metering valve 14 that regulates the amount of fuel drawn from the feed pump 10 into the pressurizing chamber 13 in the cylinder 11.

  In the fuel supply pump 4, when the plunger 12 moves in the cylinder 11 from the top dead center toward the bottom dead center, the fuel fed from the feed pump 10 is metered by the electromagnetic metering valve 14, and the suction valve 15 is pushed open and sucked into the pressurizing chamber 13. Thereafter, when the plunger 12 moves in the cylinder 11 from the bottom dead center to the top dead center, the fuel in the pressurizing chamber 13 is pressurized by the plunger 12, and the pressurized fuel passes through the discharge valve 16. Pushed open and pumped to the common rail 2.

  The injector 5 is mounted for each cylinder of the engine 1 and is connected to the common rail 2 via a high-pressure pipe 17. The injector 5 includes an electromagnetic valve 5a that operates based on a command from the ECU 6, and a nozzle 5b that injects fuel when the electromagnetic valve 5a is energized.

  The solenoid valve 5a opens and closes a low-pressure passage (not shown) that leads from the pressure chamber (not shown) to which the high-pressure fuel of the common rail 2 is applied to the low-pressure side. Shut off the low pressure passage.

  The nozzle 5b incorporates a needle (not shown) that opens and closes the nozzle hole, and the fuel pressure in the pressure chamber urges the needle in the valve closing direction (direction in which the nozzle hole is closed). Accordingly, when the low pressure passage is opened by energization of the electromagnetic valve 5a and the fuel pressure in the pressure chamber decreases, the needle rises in the nozzle 5b and opens (opens the nozzle hole), thereby being supplied from the common rail 2. High pressure fuel is injected from the nozzle hole. On the other hand, when the low pressure passage is blocked by stopping energization of the electromagnetic valve 5a and the fuel pressure in the pressure chamber rises, the needle descends in the nozzle 5b and closes, thereby terminating the injection.

  The ECU 6 includes a rotation speed sensor 18 that detects an engine rotation speed (rotation speed per minute), an accelerator opening sensor (not shown) that detects an accelerator opening (engine load), and a pressure sensor that detects a rail pressure. 7. A neutral detection sensor (not shown) for detecting whether or not the transmission is in the neutral state is connected.

The neutral detection sensor may be any sensor that detects that the clutch is in the OFF state, that is, the engine power is cut off from the drive wheels.
Then, as shown in FIG. 2, the ECU 6 shows an injection command indicating the target rail pressure of the common rail 2 and the injection timing and the injection amount suitable for the operating state of the engine 1 based on the sensor information detected by these sensors. Target value generation processing 21 as command injection amount setting means for generating (normal injection) and correction means for correcting an injection amount (hereinafter referred to as “command injection amount”) indicated in the injection command by a correction injection amount described later. In accordance with the injection amount correction process 23, the drive means for generating a drive signal for driving the electromagnetic metering valve 14 of the fuel supply pump 4 and the electromagnetic valve 5a of the injector 5 according to the corrected command injection amount and the target rail pressure. An injection command for performing single injection based on the command injection amount indicated by the injection command generated by the drive signal generation processing 25 and the sensor information and the target value generation processing 21 Form, according to the result of the single-shot injection, performing at least the injection quantity learning process 27 as the correction amount calculating means and the high-priority learning setting means obtains the correction injection amount to be used in the injection amount correction process 23.

  However, the ECU 6 performs control so that a minimum amount of pilot injection is performed by the injector 5 prior to main injection in normal injection performed according to the operating state of the engine 1, and in the injection learning processing, The injection amount is learned.

Of the above-described processes, the target value generation process 21, the injection amount correction process 23, and the drive signal generation process 25 are well known and will not be described. The following description relates to the main part of the present invention. The injection amount learning process will be described in detail.
<Injection amount learning process>
FIG. 3 is a flowchart showing the contents of the injection amount learning process.

  This process is started when an external start command is issued. However, the present invention is not limited to this, and it may be configured to start every time a predetermined period (for example, one year) elapses or every time a predetermined distance (for example, 10,000 km) travels.

  As shown in FIG. 3, when this process is started, first, in S110, priority learning as priority learning cylinder setting means for setting a cylinder for which calculation of injection correction amount (injection amount learning) should be preferentially performed as a priority learning cylinder. In step S120, the cylinder setting process is executed, and in step S120, injection correction as a correction amount calculation unit that obtains a learning value to be used when determining the correction injection amount for the priority learning cylinder specified in step S110 and calculates the injection correction amount. The amount calculation process is executed.

In S130, it is determined whether or not the injection correction amount calculation process has been executed for all the cylinders. If there is a cylinder that has not been executed, the process returns to S110, and the cylinders for which the injection correction amount calculation process has not been completed are returned. Steps S110 to S120 are repeated. On the other hand, if the injection correction amount calculation process has been completed for all the cylinders, this process is terminated.
<Priority learning cylinder setting process>
Next, FIG. 4 is a flowchart showing the processing contents in the priority learning cylinder setting processing executed in S110.

  As shown in FIG. 4, when this process is started, first, in S210, it is determined whether or not the number of learning incomplete cylinders that have not executed the injection correction amount calculation process is 1, and the number of learning incomplete cylinders is determined. If it is 1, the process proceeds to S220, the learning incomplete cylinder is set as the priority learning cylinder, and this process is terminated.

On the other hand, if it is determined in S210 that the number of incomplete learning cylinders is not 1 (that is, 2 or more), the process proceeds to S230, and it is determined whether or not a learning condition is satisfied.
Specifically, it is a non-injection time when the command injection amount indicated in the injection command (normal injection) generated in the target value generation process 21 is zero or less, and a transmission for a vehicle equipped with the fuel injection system Is a neutral condition (for example, at the time of a shift change) and that a predetermined range of rail pressure is maintained as learning conditions.

  Note that one or two of the three learning conditions described above may be used as the learning condition. Further, when an EGR device, a diesel throttle, a variable turbo, or the like is installed, the opening degree of the EGR valve, the opening degree of the diesel throttle, the opening degree of the variable turbo, etc. may be added to the learning conditions.

  If it is determined in S230 that the learning condition is not satisfied, the process waits by repeating the same step (S230). If it is determined that the learning condition is satisfied, the process proceeds to S240, and the injection timing of the incomplete learning cylinder is determined. It is determined whether or not. The injection timing can be specified by a known method based on the output of a crank sensor or a cam sensor (not shown).

  If it is determined in S240 that it is not the injection timing of the incomplete learning cylinder, the process waits by repeating the same step (S240), and if it is determined that it is the injection timing of the learning incomplete cylinder, the process proceeds to S250, By generating an injection command for injection, single injection is performed, and the process proceeds to S260.

  In S260, based on the output of the rotational speed sensor 18, the engine rotational speed fluctuation amount due to the single injection is detected. The engine speed fluctuation amount is obtained by obtaining a difference between the engine speed (estimated value) when the single injection is not performed and the engine speed obtained from the output of the rotational speed sensor 18 after the single injection is performed. It is obtained by. Since the engine speed decreases monotonously when there is no injection, the engine speed when single injection is not performed is simply estimated from the engine speed immediately before single injection and the rate of change. (See FIG. 6).

In subsequent S270, it is determined whether or not the sum of the learning completion cylinder number and the single injection execution completion cylinder number is equal to the total cylinder number.
If a negative determination is made in S270, assuming that there is an incomplete learning cylinder that has not performed single injection, the process returns to S240 and repeats the processing of S240 to S260, thereby performing single injection for the incomplete learning cylinder. To do.

  If an affirmative determination is made in S270, it is determined that single injection has been completed for all cylinders, and the flow proceeds to S280, and the processing in S250 to S260 (single injection, engine speed fluctuation amount detection) for all cylinders is performed as a learning condition. Whether or not under the condition (one learning period to be continued), that is, during the above process, normal injection control may be resumed or the rail pressure may change significantly. It is determined whether or not there was.

If the learning condition is not satisfied during the above process and a negative determination is made in S280, the engine speed variation obtained by the single injection is discarded, and the process returns to S230.
On the other hand, if an affirmative determination is made in S280, it is assumed that all single injections have been performed under the same conditions, and the process proceeds to S290, and engine torque generated by the execution of the single injection is performed for all cylinders that have performed single injection. A characteristic value (torque equivalent amount) proportional to (hereinafter referred to as “generated torque”) is calculated.

  This characteristic value Tp is obtained from the product of the engine speed fluctuation amount Δω calculated in S260 and the engine speed ω0 when the single injection is performed. The torque T of the engine 1 generated by the single injection is ( 1) It has the relationship shown to Formula.

T = K · Tp = K · Δω · ω0 (1)
K: Proportional constant In the engine 1 of this embodiment, that is, the diesel engine, the generated torque T and the actual injection amount are proportional to each other. Therefore, the characteristic value Tp calculated in S290 is also proportional to the actual injection amount.

  In subsequent S300, the fuel injection amount (actual injection amount) actually injected from the injector 5 by single injection is estimated from the characteristic value calculated in S290, and the difference between the actual injection amount and the command injection amount in single injection is estimated. Is calculated as a determination value.

In the subsequent S310, the cylinder having the largest determination value obtained in S300, that is, the cylinder having the largest difference between the actual injection amount and the designated injection amount is set as the priority learning cylinder, and this processing is terminated.
In FIG. 6, assuming that the injection timings of the cylinders # 1 to # 4 appear in the order of # 1 → # 3 → # 4 → # 2 → # 1 →. It is a schematic diagram which illustrates a mode that an engine speed changes when implemented, and the implementation timing of single injection. The points in the figure indicate the injection timing of each cylinder as in FIG.
<Injection correction amount calculation processing>
Next, FIG. 5 is a flowchart showing the processing contents in the injection correction amount calculation processing executed in S120.

  As shown in FIG. 5, when this process is started, first, in S410, as in the previous S210, it is determined whether or not the learning condition is satisfied. If the learning condition is not satisfied, the same step ( The process waits by repeating S410), and proceeds to 420 when the learning condition is satisfied.

  In S420, it is determined whether or not it is the injection timing of the priority learning cylinder set in S110. If it is not the injection timing of the priority learning cylinder, the process waits by repeating the same step (S420), and the injection of the priority learning cylinder is performed. If it is timing, the process proceeds to S430.

  In S430 and S440, as in the previous S250 and S260, single injection is performed by generating an injection command for single injection (S430), and single injection is performed based on the output of the rotation speed sensor 18 The engine speed fluctuation amount due to this is detected.

  In subsequent S450, it is determined whether or not the processing of S430 to S440 (single injection, engine speed fluctuation amount detection) was performed under the condition that the learning condition is satisfied (one continuous learning period), If a negative determination is made, the engine speed fluctuation amount obtained by the single injection is discarded, and the process returns to S410. On the other hand, if a positive determination is made, the process proceeds to S460.

  In S460, a characteristic value (torque equivalent amount) Tp proportional to the torque generated by the single injection is calculated based on the engine speed fluctuation amount detected in S440 as in the previous S290.

  In the subsequent S470, as in the previous S300, the fuel injection amount (actual injection amount) actually injected from the injector 5 by single injection is estimated from the characteristic value calculated in S460, and the actual injection amount and single injection are calculated. The difference from the command injection amount is calculated as a learning value.

  In subsequent S480, it is determined whether or not a predetermined (for example, 10) learning value has been acquired for the currently set priority learning cylinder. If a negative determination is made, the process returns to S410 and the acquisition of the learning value is repeated. If a positive determination is made, the process proceeds to S490.

In S490, based on a predetermined number of learning values acquired for the priority learning cylinder, an average value of these learning values is calculated as an injection correction amount, and this process is terminated.
That is, in this process, when the learning condition is satisfied, single injection is performed to start acquisition of the learning value, and while the learning condition is satisfied, acquisition of the learning value is repeated. However, it is not necessary to acquire a predetermined number of learning values in one learning period, and the injection correction amount is calculated using a predetermined number of learning values acquired over a plurality of learning periods.

The injection correction amount calculated by this processing is supplied to the injection amount correction processing 23 and used for correction of the command injection amount (addition with the command injection amount in the present embodiment). This is supplied to the drive signal generation process 25.
<Effect>
As described above, according to the fuel injection control device of the present embodiment, the determination value consisting of the difference between the actual injection amount and the command injection amount is obtained for all the cylinders, and the cylinder having the largest determination value is determined as the priority learning cylinder. The learning value is acquired intensively for the set priority learning cylinder.

  Therefore, according to the fuel injection control device of the present embodiment, the time required to acquire the number of learning values necessary for calculating the injection correction amount for one cylinder, and hence the injection correction amount calculated from the acquired learning value. Can be significantly reduced as compared with the conventional apparatus in which the priority learning cylinder is not set.

  Further, according to the fuel injection control device of the present embodiment, learning is completed in order from a cylinder with a large determination value (difference between the actual injection amount and the command injection amount) from time to time, that is, a cylinder with low injection amount accuracy. Since the accuracy is improved, the accuracy of the average injection amount for all the cylinders can be quickly improved.

  Furthermore, according to the fuel injection control device of the present embodiment, the determination value necessary for setting the priority learning cylinder (the amount of deviation between the command injection amount and the actual injection amount) is calculated for all the injection correction amounts that need to be calculated. Since it is obtained based on the result of performing single injection once for each cylinder, the priority learning cylinder can be set in a short time.

  Further, according to the fuel injection control device of the present embodiment, when the determination value necessary for setting the priority learning cylinder is obtained, the single injection for the required number of times is performed within one learning period. Therefore, the determination values acquired under substantially the same conditions are compared, and the cylinder to be preferentially learned can be set more accurately.

Furthermore, according to the fuel injection control device of the present embodiment, as the learning condition for performing the injection amount learning, at least, there is no injection and the transmission is in the neutral state. A fluctuation in the rotational speed of the engine 1 caused by a single injection can be accurately detected, and as a result, learning accuracy can be improved.
[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the above-described embodiment, every time learning of the priority learning cylinder is completed, that is, every time learning of one cylinder is completed, the priority learning cylinder setting process is re-executed for the incomplete learning cylinder, and each time priority is given. The learning cylinder is set, but once the priority learning cylinder setting process is executed, the learning order of all cylinders is determined, and when learning is completed for one cylinder, the priority learning cylinder specifying process is not re-executed. The learning may be performed for other cylinders.

  In the above embodiment, the injection correction amount calculation process is configured to obtain one injection correction amount for each cylinder. However, even for a single cylinder, a plurality of injection correction amounts divided according to conditions such as rail pressure. You may comprise so that it may obtain | require.

  In the priority learning cylinder setting process of the above-described embodiment, the single injection is performed once for each cylinder to obtain the determination value. However, when the variation in the engine speed variation is large, multiple single injections are performed for each cylinder. The determination value may be obtained by performing the operation one by one. In this case, the difference between the actual injection amount obtained as the determination value when setting the priority learning cylinder and the command injection amount may also be used as the learning value.

1 is an overall configuration diagram of a fuel injection device. The block diagram which shows the structure of the process which ECU performs. The flowchart which shows the content of the injection quantity learning process. The flowchart which shows the detail of a priority learning cylinder setting process. The flowchart which shows the detail of an injection correction amount calculation process. Explanatory drawing which shows the operation | movement in a priority learning cylinder setting process. Explanatory drawing which shows how to obtain | require the fluctuation | variation of the engine speed by implementation of single injection, and an engine speed fluctuation amount.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Common rail 3 ... Fuel tank 4 ... Fuel supply pump 5 ... Injector 7 ... Pressure sensor 8 ... Pressure limiter 9 ... Cam shaft 10 ... Feed pump 12 ... Plunger 13 ... Pressurizing chamber 14 ... Electromagnetic metering valve 15 ... Suction valve 16 ... Discharge valve 17 ... High-pressure piping 18 ... Rotational speed sensor 21 ... Target value generation process 23 ... Injection amount correction process 25 ... Drive signal generation process 27 ... Injection quantity learning process

Claims (5)

Command injection amount setting means for setting a command injection amount that is a fuel amount to be injected into an injector provided in each cylinder of an internal combustion engine having multiple cylinders;
Correction means for correcting the command injection amount set by the command injection amount setting means using a previously determined injection correction amount;
Drive means for driving the injector in accordance with the command injection amount corrected by the correction means;
The number of revolutions of the internal combustion engine by performing the single injection that causes the injector of any one cylinder of the internal combustion engine to perform fuel injection during the learning period in which the preset learning condition is satisfied, and performing the single injection The actual injection amount, which is the amount of fuel actually injected by the injector, or the actual injection correlation amount that has a correlation with the actual injection amount is acquired as a learning value based on the fluctuation of the actual injection amount. A correction amount calculating means for calculating the injection correction amount so that the injection amount and the command injection amount coincide;
In a fuel injection control device comprising:
A priority learning cylinder setting unit that obtains a difference between the command injection amount and the actual injection amount as a determination value for each cylinder and sets a cylinder having the largest determination value as a priority learning cylinder is provided,
The fuel injection control device, wherein the correction amount calculation means acquires the learning value for the priority learning cylinder set by the priority learning cylinder setting means.   The said priority learning cylinder setting means calculates | requires the said determination value from the result of having implemented the said single injection once for all the cylinders which need to calculate the said injection correction amount. Fuel injection control device.   3. The fuel injection control device according to claim 2, wherein the priority learning cylinder setting unit performs the single injection for a required number of times within one learning period.   The fuel injection control apparatus according to any one of claims 1 to 3, wherein the correction amount calculation means uses at least the command injection amount as zero or less as the learning condition.   The fuel injection according to any one of claims 1 to 3, wherein the correction amount calculation means uses the learning condition that at least the command injection amount is equal to or less than zero and the transmission is in a neutral state. Control device.

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