JP7419143B2 - Fuel injection control device and control method for the fuel injection control device - Google Patents

Description

The present invention relates to a fuel injection control device and a control method for the fuel injection control device for injecting fuel into the cylinders of an engine. In particular, the present invention relates to a fuel injection control device and a method of controlling the fuel injection control device that maintains constant fuel injection start timing in each cylinder of an engine.

BACKGROUND ART Conventionally, as a device for injecting fuel into the cylinders of an engine, a pressure accumulation type fuel injection control device has been used, which includes a common rail for temporarily storing fuel pressurized by a high-pressure pump. A fuel injection valve is connected to the common rail, and the fuel is injected into the cylinder of the engine by controlling the energization of the fuel injection valve while high-pressure fuel is supplied to the fuel injection valve.

How to control fuel injection in an engine is an important issue that greatly affects the operating performance of the engine, and various control methods have been proposed and put into practical use. For example, it is well known that pilot injection is performed in diesel engines in order to moderate combustion, reduce engine vibration during combustion, and purify exhaust gas.

In order to ensure sufficient and reliable effects as described above, such pilot injection requires precise control of the minute injection amount. There are variations in characteristics, and it is inevitable that a deviation will occur between the instructed injection amount and the actual injection amount. Therefore, in pilot injection control to eliminate the above-described deviation in injection amount, correction control of the injection amount is generally performed.

As techniques for correcting the pilot injection amount, for example, the following methods are known. In other words, while the accelerator pedal is released and the fuel injection amount is zero, and the vehicle is coasting, multiple small injections are performed while changing the energization time, and the resulting fluctuation in crankshaft angular velocity is Based on this, the estimated value of the injection amount that would have actually been injected at that time (estimated injection amount) is calculated, and the energization time is corrected based on the difference between the estimated injection amount and a preset reference injection amount ( For example, see Patent Document 1).

JP2013-15076

The timing to start energizing the fuel injection valve when injecting fuel is set as a predetermined crank angle based on the compression top dead center of the piston for each engine model and for each operating condition. However, due to the above-mentioned variations in fuel injection valves, even if the energization start timing is the same, the actual fuel injection start timing may differ for each cylinder of the engine.

If the fuel injection start timing differs depending on the cylinder, combustion will occur under different conditions such as cylinder internal pressure and piston position at the time of fuel injection, so the energy generated by combustion will differ depending on the cylinder. If the fuel injection amount is corrected using the technique disclosed in Patent Document 1 in such a state, the amount of fluctuation in the angular velocity of the crankshaft due to the minute injection becomes uniform in each cylinder of the engine, but the injection amount in each cylinder becomes There may be deviations.

If the engine is operated with the fuel injection start timings being shifted depending on the cylinders, there is a possibility that the injection amounts of things other than pilot injection, such as main injection and post injection, may also be shifted depending on the cylinders.

The present invention was developed in view of this situation, and is an object of the present invention to improve the accuracy of fuel injection control by correcting variations in fuel injection start timing between cylinders using correction control of minute injection amounts. The present invention provides a fuel injection control device and a control method for the fuel injection control device.

In order to solve the above issues,
A fuel injection control device for an engine having multiple cylinders,
An estimated injection amount that is estimated to have been injected during the micro injection is calculated based on the amount of fluctuation in the angular velocity of the crankshaft when the micro injection, which is a fuel injection with a small injection amount, is performed multiple times while changing the energization time, and the The difference between the energization time when the estimated injection amount becomes the target injection amount and a predetermined reference energization time is obtained as a differential energization time learning value, and the energization time of the minute injection is determined by the difference energization time learning value. a minute injection amount correction section that performs correction;
a first angular velocity that obtains a relationship between an angular velocity fluctuation amount of the crankshaft caused by a corrected microinjection, which is a microinjection corrected by the differential energization time learning value obtained in the microinjection amount correction unit, and the engine rotation speed; A fluctuation amount acquisition unit,
A second angular velocity fluctuation that performs the corrected micro-injection while changing the energization start timing to the fuel injection valve, and obtains the relationship between the energization start timing, the angular velocity fluctuation amount of the crankshaft, and the engine rotation speed at that time. A quantity acquisition unit;
The relationship between the angular velocity fluctuation amount of the crankshaft and the engine rotation speed acquired by the first angular velocity fluctuation amount acquisition unit, and the energization start timing and the angular velocity of the crankshaft acquired by the second angular velocity fluctuation amount acquisition unit The relationship between the energization start timing and the angular velocity fluctuation amount of the crankshaft, which excludes a deviation in the angular velocity fluctuation amount of the crankshaft caused by the difference in the engine rotation speed, based on the relationship between the fluctuation amount and the engine rotation speed. an engine rotation speed influence correction section that obtains the
Based on the relationship between the energization start timing and the angular velocity fluctuation amount of the crankshaft acquired by the engine rotation speed influence correction unit, the maximum value of the angular velocity fluctuation amount of the crankshaft and the angular velocity fluctuation amount of the crankshaft are an angular velocity variation maximum value acquisition unit that acquires the energization start timing that is the maximum value;
Based on the energization start timing at which the angular velocity variation of the crankshaft reaches the maximum value, the fuel for each cylinder is adjusted such that the angular velocity variation of the crankshaft due to fuel injection in each cylinder reaches the maximum value. an energization start timing correction unit that makes fuel injection start timing constant for each of the cylinders by correcting the energization start timing for the injector;
A fuel injection control device is provided.

In addition, in order to solve the above problems,
A method of controlling a fuel injection control device for an engine having a plurality of cylinders, the method comprising:
The minute injection amount correction unit estimates that the fuel was injected during the minute injection based on the amount of fluctuation in the angular velocity of the crankshaft when the minute injection, which is fuel injection with a minute injection amount, is executed multiple times while changing the energization time. Calculate the estimated injection amount, obtain the difference between the energization time when the estimated injection amount becomes the target injection amount and a predetermined reference energization time as a differential energization time learning value, and use the differential energization time learning value. a step of correcting the energization time of the micro-injection;
The first angular velocity fluctuation amount acquisition unit determines the angular velocity fluctuation amount of the crankshaft and the engine rotation speed caused by the corrected minute injection, which is the minute injection corrected by the differential energization time learning value acquired by the minute injection amount correction unit. a step of obtaining a relationship with
The second angular velocity fluctuation amount acquisition unit performs the corrected micro-injection while changing the energization start timing to the fuel injector, and at that time, the energization start timing, the angular velocity fluctuation amount of the crankshaft, and the engine rotation speed. a step of obtaining the relationship of
The engine rotational speed influence correction unit calculates the relationship between the angular velocity fluctuation amount of the crankshaft and the engine rotational speed acquired by the first angular velocity fluctuation amount acquisition unit, and the energization acquired by the second angular velocity fluctuation amount acquisition unit. Based on the relationship between the start timing, the angular velocity variation of the crankshaft, and the engine rotational speed, the energization start timing and the crankshaft are determined by eliminating a deviation in the angular velocity variation of the crankshaft caused by the difference in the engine rotational speed. obtaining a relationship with the angular velocity variation of the shaft ;
An angular velocity variation maximum value acquisition unit obtains a maximum value of the angular velocity variation of the crankshaft based on the relationship between the energization start timing and the angular velocity variation of the crankshaft acquired by the engine rotation speed influence correction unit , and acquiring the energization start timing at which the angular velocity fluctuation amount of the crankshaft reaches the maximum value ; and the energization start timing correction section determines each of the energization start timings at which the angular velocity fluctuation amount of the crankshaft reaches the maximum value. Starting fuel injection for each cylinder by correcting the energization start timing for the fuel injection valve for each cylinder so that the angular velocity fluctuation amount of the crankshaft due to fuel injection in the cylinder becomes the maximum value . a step of keeping the timing constant;
A method of controlling a fuel injection control device is provided.

According to the present invention, the accuracy of injection amount control can be improved by making the fuel injection start timing constant between cylinders of the engine.

1 is a diagram showing a configuration example of a fuel injection control device in an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a portion of the electronic control unit that constitutes the fuel injection control device, which is related to the implementation of the present invention. FIG. 3 is a diagram showing the relationship between engine rotation speed and crankshaft angular velocity fluctuation amount. FIG. 3 is a diagram showing the relationship between the timing of starting energization to a fuel injection valve and the amount of fluctuation in angular velocity of the crankshaft. FIG. 3 is a diagram showing the relationship between the energization start timing and the angular velocity fluctuation amount of the crankshaft, excluding the influence of the engine rotation speed. FIG. 3 is a diagram showing a difference in the maximum value of the angular velocity fluctuation amount of the crankshaft between cylinders. FIG. 7 is a diagram showing the relationship between the energization start timing and the angular velocity fluctuation amount of the crankshaft in each cylinder. It is a subroutine flowchart showing an example of the operation of the electronic control unit in the embodiment of the present invention.

Embodiments of the present invention will be described below with appropriate reference to the drawings. Note that the members, arrangement, etc. described below do not limit the present invention, and can be variously modified within the scope of the spirit of the present invention. Further, in each figure, the same reference numerals indicate the same elements, and the description thereof will be omitted as appropriate.

FIG. 1 shows the overall configuration of a fuel injection control device 10 according to this embodiment. The fuel injection control device 10 according to this embodiment is a pressure accumulation type fuel injection control device. The fuel injection control device 10 is a device for injecting fuel into a cylinder of an engine (not shown) mounted on a vehicle, and includes a fuel tank 1, a low pressure pump 11, a fuel filter 12, a high pressure pump 13, The main elements include a flow rate control valve 19, a common rail 15, a pressure control valve 23, a fuel injection valve 17, an electronic control unit 50 (ECU), and the like.

The low pressure pump 11 and the high pressure pump 13 are connected by a low pressure fuel passage 31, and the high pressure pump 13 and the common rail 15, and the common rail 15 and the fuel injection valve 17 are connected by high pressure fuel passages 33 and 35, respectively. Furthermore, return passages 37, 38, and 39 are connected to the high-pressure pump 13, the common rail 15, and the fuel injection valve 17, respectively, for returning surplus fuel that is not injected from the fuel injection valve 17 to the fuel tank 1.

The low-pressure pump 11 sucks up and pressure-feeds the fuel in the fuel tank 1, and supplies the fuel to the high-pressure pump 13 via the low-pressure fuel passage 31. This low-pressure pump 11 is an in-tank type electric pump provided in the fuel tank 1, and is operated by electric current supplied from a battery. However, the low pressure pump 11 may be provided outside the fuel tank 1, or may be provided integrally with the high pressure pump 13.

A flow control valve 19 is provided at the low-pressure fuel inlet portion of the high-pressure pump 13 to adjust the discharge amount of the high-pressure pump. The flow rate control valve 19 is an electromagnetic proportional control valve in which the stroke amount of the valve member is variable depending on the supplied current value, and the area of the fuel passage can be adjusted.

The high-pressure pump 13 pressurizes the fuel introduced via the flow control valve 19 by the low-pressure pump 11 and pumps it to the common rail 15 via the high-pressure fuel passage 33.

The common rail 15 accumulates high-pressure fuel pressurized by the high-pressure pump 13 and supplies the fuel to each fuel injection valve 17 connected via a high-pressure fuel passage 35. A rail pressure sensor 25 and a pressure control valve 23 are attached to this common rail 15.

The rail pressure sensor 25 detects the pressure within the common rail 15 (rail pressure). The sensor signal of the rail pressure sensor 25 is sent to the electronic control unit 50.

The pressure control valve 23 is used to adjust the rail pressure by adjusting the flow rate of high-pressure fuel returned from the common rail 15 to the fuel tank 1. The pressure control valve 23 is an electromagnetic proportional control valve in which the stroke amount of a valve member for opening and closing a fuel passage is variable depending on the amount of electricity supplied, and the area of the fuel passage can be adjusted. Furthermore, instead of the pressure control valve 23, a mechanical safety valve that opens when a predetermined pressure is reached may be used.

The fuel injection valve 17 includes a nozzle body provided with an injection hole, and a nozzle needle that opens and closes the injection hole by moving forward and backward. In the fuel injection valve 17, the injection hole is closed by applying back pressure to the rear end side of the nozzle needle, and the injection hole is opened by releasing the applied back pressure. As the back pressure control means for the fuel injection valve 17, an electrostrictive actuator equipped with a piezo element or an electromagnetic solenoid actuator is used.

The electronic control unit 50 is mainly composed of a microcomputer with a known configuration, and has storage elements such as RAM and ROM, and has a drive circuit for driving the fuel injection valve 17, a flow control valve 19, and a pressure control valve 23. Equipped with an energizing circuit for energizing. In addition to inputting the detection signal of the rail pressure sensor 25 to the electronic control unit 50, various detection signals such as engine rotation speed, accelerator opening, and fuel temperature are used for engine operation control and fuel injection control. It is intended to be entered in order to serve the user. Furthermore, the electronic control unit 50 includes various control sections according to the implementation of the present invention, as shown in FIG.

Next, a configuration example of the electronic control unit 50 for implementing the present invention will be described with reference to FIG. 2. FIG. 2 is a block diagram schematically showing the configuration of a portion of the electronic control unit 50 related to implementation of the present invention.

The electronic control unit 50 includes a minute injection amount correction section 500, a learning condition setting section 510, a correction energization time changing section 520, a first angular velocity fluctuation amount acquisition section 530, a second angular velocity fluctuation amount acquisition section 540, and an engine control unit 50. It includes a rotational speed influence correction section 550, an angular velocity variation maximum value acquisition section 560, a minute injection amount re-correction section 570, and an energization start timing correction section 580.

The micro injection amount correction unit 500 executes micro injection, which is fuel injection with a small injection amount, multiple times while changing the energization time when the accelerator opening is zero and the vehicle is coasting. The injection amount of the pilot injection is corrected based on the amount of variation in the angular velocity of the crankshaft that occurs. This injection amount correction has been conventionally performed.

Specifically, the micro-injection amount correction unit 500 calculates an estimated injection amount, which is an estimated value of the injection amount that would have been injected at that time, based on the amount of variation in the angular velocity of the crankshaft caused by the micro-injection. Then, if the estimated injection amount calculated for the first time exceeds a predetermined target injection amount, the micro injection amount correction unit 500 performs micro injection in the micro injection so that the estimated injection amount approaches the target injection amount. The estimated injection amount is repeatedly acquired while decreasing the amount. On the other hand, if the estimated injection amount calculated for the first time is less than a predetermined target injection amount, the micro injection amount correction unit 500 performs micro injection in the micro injection so that the estimated injection amount approaches the target injection amount. The estimated injection amount is repeatedly acquired while increasing the amount. Then, the difference ΔET between the energization time ET and the reference energization time when the estimated injection amount becomes the target injection amount becomes the differential energization time learning value. Note that a predetermined tolerance range may be set for the target injection amount, and the range within the tolerance range may be treated as the target injection amount in this process.

In this embodiment, the minute injection amount correction unit 500 calculates a value obtained by subtracting the reference energization time from the energization time ET when the estimated injection amount reaches the target injection amount as the differential energization time learning value ΔET. Here, the reference energization time is stored in advance in an appropriate area of the electronic control unit 50.

The differential energization time learning value ΔET is stored in an appropriate area of the electronic control unit 50, and is used hereafter mainly for correcting the energization time of pilot injection. The differential energization time learning value ΔET can take both positive and negative values. When the differential energization time learning value ΔET is a positive value, the small injection amount correction unit 500 increases the pilot injection energization time by ΔET with respect to the reference energization time. On the other hand, when the differential energization time learning value ΔET is a negative value, the pilot injection energization time is decreased by ΔET with respect to the reference energization time.

Calculation of the differential energization time learning value ΔET in the small injection amount correction unit 500 is performed under various operating conditions while changing the rail pressure and engine rotation speed. Further, the target injection amount of the minute injection executed in the minute injection amount correction unit 500 can be predetermined for each operating condition, or can be set as the pilot injection amount when the engine is actually operated under each operating condition. You can also.

Among the processes shown in FIG. 2, the processes other than those in the small injection amount correction section 500 are unique to the present invention. That is, the present invention corrects the fuel injection start timing using data obtained in the processing of the small injection amount correction section 500. In addition, in processes other than those in the minute injection amount correction section 500, all minute injections are performed when the vehicle is coasting, with the accelerator opening being zero.

The learning condition setting unit 510 sets learning conditions for fuel injection start timing correction in the present invention. Specifically, the learning condition setting unit 510 sets the cylinder and rail pressures for obtaining the maximum value of the angular velocity fluctuation amount of the crankshaft, which will be described later. As an example, in the present embodiment, the learning condition initially set in the learning condition setting section 510 will be described assuming that the first cylinder and the rail pressure are 60 [MPa].

The corrected energization time change unit 520 reflects the differential energization time learning value ΔET obtained by the minute injection amount correction unit 500 on the end timing of the energization time of the minute injection under each operating condition. Specifically, when the differential energization time learning value ΔET is a positive value, the corrected energization time changing unit 520 delays the timing of the end of energization of the minute injection under the operating condition by ΔET. On the other hand, when the differential energization time learning value ΔET is a negative value, the timing at which the energization of the minute injection ends under the relevant operating condition is advanced by ΔET.

As a conventional method for correcting the energization time for pilot injection, it is common to correct the energization start timing for pilot injection using a differential energization time learning value ΔET. However, the purpose of the present invention is to make the fuel injection start timing of the fuel injection valve 17 in each cylinder uniform. Therefore, in the corrected energization time changing section 520, the correction amount obtained in the minute injection amount correction section 500 is reflected in the timing of ending energization. In other words, the correction amount obtained by the small injection amount correction unit 500 is used to make the small injection amount substantially uniform under each operating condition, and the variation in fuel injection start timing in each cylinder is The state caused by the variation in is maintained.

The first angular velocity fluctuation amount acquisition unit 530 executes a minute injection while changing the engine speed at a predetermined rail pressure, and acquires the relationship shown in FIG. 3. In FIG. 3, the horizontal axis shows the engine rotational speed, and the vertical axis shows the amount of variation in the angular velocity of the crankshaft. Incidentally, the amount of fluctuation in the angular velocity of the crankshaft is the difference between the angular velocity ω1 [rad/s] before the minute injection and the angular velocity ω2 [rad/s] after the minute injection, Δω = (ω2 - ω1) [rad/s] It can be done. Further, as the angular velocity fluctuation amount of the crankshaft, a value obtained by performing predetermined signal processing in the electronic control unit 50 on the above ω1 and ω2 or Δω can also be used.

In the first angular velocity fluctuation amount acquisition unit 530, the minute injection executed to acquire the image shown in FIG. 3 is performed during the energization time in which the energization end timing has been corrected in the corrected energization time changing unit 520. Further, the same applies to the minute injection in the second angular velocity fluctuation amount acquisition section 540, which will be described later.

FIG. 3 shows data obtained by performing a minute injection at a predetermined energization start timing at a rail pressure of 60 [MPa]. As can be seen from FIG. 3, even if the rail pressure and energization start timing are the same, the amount of angular velocity fluctuation of the crankshaft differs when the engine speed differs. This is thought to be due to the fact that even if the engine is in a small injection under the same operating conditions, the cylinder internal pressure, piston position, etc. during combustion will differ if the engine speed differs.

In implementing the present invention, the relationships shown in FIG. 3 are stored in appropriate areas of the electronic control unit 50. Further, this information is used in an engine rotation speed influence correction unit 550, which will be described later.

The second angular velocity fluctuation amount acquisition unit 540 executes a small injection while changing the energization start timing to the fuel injection valve 17 while the vehicle is coasting, and acquires the engine rotation speed and the angular velocity fluctuation amount of the crankshaft at that time. .

Here, the relationship between the energization start timing for the fuel injection valve 17 and the angular velocity fluctuation amount of the crankshaft in microinjection will be explained using FIG. 4 as an example. In FIGS. 4A and 4B, the horizontal axis shows the current supply start timing, and the vertical axis shows the angular velocity fluctuation amount of the crankshaft. Note that the horizontal axis represents the retard side from the compression top dead center, and 0 [deg] corresponds to the compression top dead center. As an example, FIG. 4(a) shows the relationship between the energization start timing and the angular velocity fluctuation amount when the rail pressure is 60 [MPa] and the engine speed is 1400 [rpm], and FIG. The relationship between the energization start timing and the angular velocity fluctuation amount at [MPa] and engine speed 2200 [rpm] is shown.

In FIG. 4A, when the rail pressure is 60 [MPa] and the engine speed is 1400 [rpm], the angular velocity variation peaks when the current supply start timing is around 10 [deg] after compression top dead center. Further, in FIG. 4(b), when the rail pressure is 60 [MPa] and the engine speed is 2200 [rpm], the angular velocity fluctuation amount reaches its peak when the current supply start timing is around 13 [deg] after the compression top dead center. In other words, FIG. 4 shows that even if the rail pressure is the same, if the engine speed is different, the timing at which the energization starts at which the angular velocity variation due to the minute injection reaches its peak differs.

The engine rotational speed influence correction unit 550 corrects the influence of the engine rotational speed on the angular velocity variation of the crankshaft obtained in the process of the second angular velocity variation acquisition unit 540 using FIG. 3 .

Specifically, the engine rotation speed influence correction unit 550 performs the following processing. First, the engine speed influence correction section 550 reads a reference engine speed from the electronic control unit 50. This can be set in advance at the development stage. The present embodiment will be described with reference to 1400 [rpm] as an example.

In FIG. 3, the angular velocity fluctuation amount of the crankshaft at an engine speed of 1400 [rpm] is set as A1400, the angular speed fluctuation amount of the crankshaft at an engine speed of 1600 [rpm] is set as A1600, and the value obtained by dividing A1600 by A1400 is set as A1600_cor. . That is,
A1600/A1400=A1600_cor
Therefore, by dividing the angular velocity fluctuation amount A1600 at the engine speed of 1600 [rpm] by A1600_cor, it is possible to correct the variation in the angular speed fluctuation amount at the engine speed of 1600 [rpm] due to the engine speed. That is, A1600/A1600_cor becomes equal to A1400.

Using a similar method, the engine rotation speed influence correction unit 550 calculates the engine rotation Variations due to numbers can be corrected. In other words, the engine rotational speed influence correction unit 550 eliminates the deviation in the angular velocity variation caused by the difference in engine rotational speed from the angular velocity variation at the reference engine rotational speed of 1400 [rpm].

Note that, prior to executing this process, the engine speed influence correction unit 550 performs a filtering process on the angular velocity fluctuation amount of the crankshaft obtained in the processing of the second angular velocity fluctuation amount acquisition unit 540 to eliminate abnormalities such as noise. Remove value.

Through this process, the engine rotational speed influence correction unit 550 acquires data indicating the relationship between the energization start timing and the angular velocity fluctuation amount, which is independent of the engine rotational speed, at a rail pressure of 60 [MPa].

The maximum angular velocity variation acquisition unit 560 obtains the maximum value of the angular velocity variation of the crankshaft and the angular velocity variation of the crankshaft at a rail pressure of 60 [MPa] from the data obtained by the engine rotation speed influence correction unit 550. Obtain the energization start timing when is the maximum. Specifically, the angular velocity variation maximum value acquisition unit 560 approximates the data obtained by the engine rotation speed influence correction unit 550, which indicates the relationship between the energization start timing and the angular velocity variation of the crankshaft, with a curve. , a diagram shown in FIG. 5 is created, and the maximum value D60 of the angular velocity fluctuation amount and the current energization start timing T60_1 are obtained from FIG.

The minute injection amount re-correction unit 570 determines whether the maximum value D60 of the angular velocity fluctuation amount of the crankshaft acquired by the angular velocity fluctuation maximum value acquisition unit 560 is within a predetermined target range, and corrects the angular velocity fluctuation. If the maximum value D60 of the amount is not within the target range, the corrected energization time changing unit 520 further corrects the energization end timing of the corrected energization time ET.

Specifically, if the maximum value D60 of the angular velocity variation amount acquired by the angular velocity variation maximum value acquisition unit 560 exceeds the upper limit of the target range, the minute injection amount re-correction unit 570 adjusts the amount after the correction by the correction energization time change unit 520. The energization end timing of the energization time ET is advanced by a predetermined amount. In addition, if the maximum value D60 of the angular velocity variation amount acquired by the angular velocity variation maximum value acquisition unit 560 is below the lower limit of the target range, the minute injection amount re-correction unit 570 controls the energization time after correction by the correction energization time change unit 520. The ET energization end timing is delayed by a predetermined amount.

FIG. 6 is a diagram for explaining the processing by the minute injection amount re-correction section 570. In FIG. 6, two types of cases ex_1 and ex_2 are depicted as examples showing the relationship between the energization start timing and the angular velocity fluctuation amount in two certain cylinders. Although the processing in the small injection amount re-correction section 570 is actually performed on all cylinders, only two cylinders are illustrated in FIG. 6 for ease of understanding. T0 is the energization start timing at which the process of the small injection amount correction unit 500 is executed. ω0 represents the target injection amount in the processing of the small injection amount correction unit 500 as a corresponding angular velocity fluctuation amount. Due to the processing in the small injection amount correction unit 500, the angular velocity fluctuation amount at the energization start timing T0 is set to ω0 for both ex_1 and ex_2.

Further, ex_1 indicates the maximum value D60_1 of the angular velocity variation amount at timing T1 where the energization start timing is different from T0, and ex_2 indicates the maximum value D60_1 of the angular velocity variation amount when the energization start timing is T2 different from T0 or T1. The value D60_2 is shown.

That is, in both ex_1 and ex_2, the angular velocity fluctuation amount is ω0 at the energization start timing T0, but the angular velocity fluctuation amount reaches the maximum value at the energization start timing different from T0.

In case ex_2, the maximum value D60_2 of the angular velocity variation exceeds the upper limit of the target range D60_trg defined by the minute injection amount re-correction unit 570. Therefore, the minute injection amount re-correction section 570 performs re-correction so as to advance the energization end timing of the energization time ET after correction by the corrected energization time changing section 520 by a predetermined amount.

On the other hand, in case ex_1, the maximum value D60_2 of the angular velocity fluctuation amount is within the target range D60_trg defined by the minute injection amount re-correction unit 570. Therefore, the re-correction by the small injection amount re-correction section 570 is not performed.

Further, if the maximum value D60_1 of the angular velocity fluctuation amount is less than the lower limit of the target range D60_trg due to the influence of deterioration etc., for example in the case of ex_1, the minute injection amount re-correction unit 570 adjusts the correction energization time change unit 520 to Re-correction is performed so that the energization end timing of the corrected energization time ET is delayed by a predetermined amount.

This is based on the following points of view. That is, the correction in the small injection amount correction section 500 is performed at a predetermined energization start timing T0. However, in each cylinder, even if the injection amount is corrected based on the angular velocity fluctuation amount at the energization start timing T0, the maximum value of the angular velocity fluctuation amount, that is, the injection amount, may deviate at other energization start timings. Alternatively, the maximum value of the angular velocity fluctuation amount may deviate because the above-described processing in the corrected energization time changing section 520 is executed after the correction in the small injection amount correction section 500 is executed. Furthermore, after the correction in the small injection amount correction section 500 is executed, the maximum value of the angular velocity fluctuation amount may deviate due to deterioration of the fuel injection valve.

In the small injection amount re-correction section 570, these deviations are corrected. That is, in the minute injection amount re-correction section 570, correction is performed so that the maximum value of the angular velocity fluctuation amount falls within the target range D60_trg. Thereafter, by correcting the energization start timing, which will be described later, it is possible to correct variations in injection amount among the cylinders with higher accuracy.

Note that the target range for the maximum value of the angular velocity fluctuation amount in the processing by the minute injection amount re-correction unit 570 and the above-mentioned predetermined amount when further correcting the energization time ET after correction by the correction energization time changing unit 520 are determined by the test. The injection amount is determined in advance through a simulation or simulation, and is stored in the minute injection amount re-correction section 570.

Further, acquisition of the maximum value of the angular velocity variation amount by the angular velocity variation maximum value acquisition unit 560 is executed for a predetermined number of rail pressures in all cylinders. The predetermined number of rail pressures is set in advance and stored in the learning condition setting unit 510.

The energization start timing correction unit 580 corrects the energization start timing of each fuel injector 17 after the maximum value of the angular velocity fluctuation amount of the crankshaft and the current energization start timing for each cylinder and each rail pressure are acquired.

The energization start timing correction unit 580 creates a diagram showing the relationship between the angular velocity fluctuation amount of the crankshaft and the energization start timing in each cylinder for each rail pressure. FIG. 7 shows, as an example, the relationship between the energization start timing at a rail pressure of 60 [MPa] and the angular velocity fluctuation amount of the crankshaft in each cylinder. In FIG. 7, the solid line indicates the first cylinder, the broken line indicates the second cylinder, the one-dot chain line indicates the fourth cylinder, and the two-dot chain line indicates the third cylinder.

In FIG. 7, the energization start timings at which the angular velocity fluctuation amount during minute injection peaks in the first, second, third, and fourth cylinders are respectively depicted as T60_1, T60_2, T60_3, and T60_4. There is. T60_1 is the most advanced angle side, and from there, T60_2, T60_4, and T60_3 go to the retarded side in that order. Here, the reason why the peaks of the angular velocity fluctuation amounts in each cylinder are substantially the same is because the processing by the minute injection amount re-correction section 570 has been performed.

In this embodiment, the energization start timing correction unit 580 corrects the energization start timings of other cylinders with the first cylinder as a reference. Comparing the first cylinder and the second cylinder, the energization start timing at which the angular velocity variation peaks is delayed in the second cylinder by (T60_2) - (T60_1) = ΔT2[deg] than in the first cylinder. Shifted to the side. Therefore, the energization start timing correction unit 580 performs a correction to shift the energization start timing of the second cylinder during fuel injection toward the advance side by ΔT2.

Similarly, the energization start timing correction unit 580 corrects the energization start timings for the third and fourth cylinders by shifting them toward the advance side by ΔT3 and ΔT4, respectively.

By performing this correction, it is possible to match the fuel injection start timings of each cylinder. This is based on the inventor's knowledge that the deviation in the energization start timing when the angular velocity fluctuation amount of the crankshaft due to minute injection reaches its peak coincides with the deviation in the fuel injection start timing.

In the above-described embodiment, the energization start timings of the other cylinders are corrected using the first cylinder as a reference, but the correction may be made using the other cylinders as a reference. Alternatively, the reference energization start timing may be determined in advance, and the energization start timing of each cylinder may be corrected in accordance with the deviation from the reference value.

Next, the procedure for implementing the present invention will be explained with reference to the subroutine flowchart shown in FIG. This subroutine flowchart is repeated at predetermined intervals while the vehicle is driving.

First, in step S102, the electronic control unit 50 determines whether the small injection amount learning conditions are satisfied and the differential energization time learning value ΔET is stored. The minute injection amount learning condition is a vehicle operating condition under which the minute injection amount correction performed by the minute injection amount correction section 500 can be executed. Specifically, the electronic control unit 50 determines whether or not the accelerator opening is zero and the vehicle is running by inertia. In addition to the above, another condition may be appropriately added as the small injection amount learning condition. Another condition may be, for example, that the gear of the vehicle is 3rd or higher, the cooling water temperature is higher than a predetermined value, and the vehicle speed is higher than a predetermined value.

Regarding whether or not the differential energization time learning value ΔET is stored, specifically, the differential energization time learning value ΔET calculated by the minute injection amount correction section 500 is stored in an appropriate area of the electronic control unit 50. It is determined whether or not. In other words, it is determined whether or not the small injection amount correction section 500 has performed correction in the past operation.

If the determination in step S102 is YES, the process advances to step S104. On the other hand, if the determination in step S102 is NO, it is assumed that the driving conditions of the vehicle are not in a state where the present invention can be executed, and the process returns to the main routine (not shown).

In step S104, the learning condition setting unit 510 sets conditions for implementing the present invention. Specifically, the cylinder and rail pressure to be subjected to the energization start timing correction of the present invention are set. The cylinder and rail pressures set in the learning condition setting unit 510 are selected from among the learning conditions for which small injection amount learning was performed in the past, which were confirmed in step S102. In this embodiment, as an example, the conditions set in the learning condition setting section 510 are the first cylinder and the rail pressure of 60 [MPa].

In the subsequent step S106, the corrected energization time changing section 520 performs a process of reflecting the differential energization time learning value ΔET calculated by the minute injection amount correction section 500 on the energization end timing of the minute injection. This is because, as described above, the differential energization time learning value ΔET calculated by the minute injection amount correction unit 500 is used to correct the energization start timing during minute injection before implementation of the present invention. In this step, the energization end timing of the minute injection is delayed or advanced by the differential energization time learning value ΔET.

In subsequent step S108, it is determined whether the first angular velocity variation acquisition unit 530 has acquired the relationship between the angular velocity variation of the crankshaft and the engine rotational speed Ne during minute injection. Specifically, in the first cylinder, a minute injection is performed at a predetermined number of engine revolutions under the condition of a rail pressure of 60 [MPa], and it is determined whether the angular velocity fluctuation amount of the crankshaft at that time has been acquired. be done.

If the determination is YES in step S108, the process proceeds to step S110, while if the determination is NO in step S108, the process proceeds to step S130.

In step S130, the first angular velocity variation acquisition unit 530 performs minute injection in the first cylinder at a predetermined number of engine speeds under the condition of a rail pressure of 60 [MPa], and at each engine speed at that time. The amount of angular velocity fluctuation of the crankshaft is obtained, and the diagram shown in FIG. 3 is created. After the diagram in FIG. 3 is created, the process returns to the main routine (not shown).

In step S110, the second angular velocity variation acquisition unit 540 executes a minute injection in the first cylinder under the condition of a rail pressure of 60 [MPa] while changing the energization start timing to the fuel injection valve 17. Obtain the amount of angular velocity fluctuation of the crankshaft. Since the second angular velocity variation acquisition unit 540 executes minute injections during coasting, the engine rotation speed at each minute injection is different. Therefore, the second angular velocity fluctuation amount acquisition unit 540 records the energization start timing, the crankshaft angular velocity fluctuation amount, and the engine rotation speed for each microinjection, and this data is used in the engine rotation speed influence correction unit 550 (described later). used.

In step S112, the engine speed influence correction section 550 adjusts the engine speed in the relationship between the energization start timing and the crankshaft angular speed fluctuation amount in each microinjection obtained by the second angular speed fluctuation amount acquisition section 540. The influence is corrected using FIG. 3 obtained in the process of the first angular velocity fluctuation amount acquisition unit 530. Note that, prior to executing this process, the engine speed influence correction unit 550 performs a filtering process on the angular velocity fluctuation amount of the crankshaft obtained in the processing of the second angular velocity fluctuation amount acquisition unit 540 to eliminate abnormalities such as noise. Remove value. Since the specific contents of the correction executed by the engine rotation speed influence correction section 550 have already been explained, the explanation will not be repeated here.

In the subsequent step S114, the angular velocity variation maximum value acquisition unit 560 creates the diagram of FIG. The maximum value D60 (peak value) of the angular velocity fluctuation amount of the crankshaft is obtained. The angular velocity variation maximum value obtaining unit 560 also obtains the energization start timing (T60_1) when the angular velocity variation of the crankshaft reaches the maximum value D60.

In the subsequent step S116, the minute injection amount re-correction unit 570 determines whether the maximum value D60 of the angular velocity fluctuation amount acquired by the angular velocity fluctuation maximum value acquisition unit 560 is within a predetermined target range. Specifically, in step S116, the small injection amount re-correction unit 570 determines whether the maximum value D60 of the angular velocity fluctuation amount of the crankshaft acquired in step S114 exceeds a predetermined upper limit threshold. If the determination is YES in step S116, the process proceeds to step S118, while if the determination is NO in step S116, the process proceeds to step S120.

In step S118, the minute injection amount re-correction section 570 performs re-correction so as to advance the energization end timing of the energization time ET after correction by the corrected energization time changing section 520 by a predetermined amount, and the process returns to step S106.

In step S120, the minute injection amount re-correction unit 570 determines whether the maximum value D60 of the angular velocity fluctuation amount of the crankshaft acquired in step S114 is below a predetermined lower limit threshold. If the determination is YES in step S120, the process proceeds to step S122, while if the determination is NO in step S120, the process proceeds to step S124.

In step S122, the minute injection amount re-correction section 570 performs re-correction so as to delay the energization end timing of the energization time ET after correction by the corrected energization time changing section 520 by a predetermined amount.

In step S124, the angular velocity variation maximum value acquisition unit 560 sets the energization start timing (T60_1) when the angular velocity variation of the crankshaft reaches the maximum value, obtained in step S114, to an appropriate value of the electronic control unit 50. Save to area.

In the subsequent step 126, the angular velocity variation maximum value acquisition unit 560 sets the energization start timing when the angular velocity variation of the crankshaft reaches the maximum value, which is obtained in step S124, to all cylinders and the preset timing. It is determined whether all the rail pressures have been acquired. If the determination in step S126 is YES, the process advances to step S128. On the other hand, if the determination in step S126 is NO, the process returns to the main routine (not shown), and the above-described process is repeated until the determination in S126 becomes YES.

In step S128, the energization start timing correction unit 580 corrects the energization start timing for each cylinder and each rail pressure. The specific correction procedure has already been explained in the description regarding the energization start timing correction section 580, so the explanation will not be repeated here.

As described above, according to the present invention, the precision of fuel injection control is improved by correcting variations in fuel injection start timing between cylinders using conventionally performed correction control of minute injection amount. can be improved.

10: fuel injection control device, 17: fuel injection valve, 50: electronic control unit, 500: minute injection amount correction section, 510: learning condition setting section, 520: correction energization time changing section, 530: first angular velocity fluctuation amount acquisition 540: Second angular velocity variation acquisition unit, 550: Engine speed influence correction unit, 560: Maximum angular velocity variation acquisition unit, 570: Minute injection amount re-correction unit, 580: Energization start timing correction unit

Claims (6)

A fuel injection control device for an engine having multiple cylinders,
An estimated injection amount that is estimated to have been injected during the micro injection is calculated based on the amount of fluctuation in the angular velocity of the crankshaft when the micro injection, which is a fuel injection with a small injection amount, is performed multiple times while changing the energization time, and the The difference between the energization time when the estimated injection amount becomes the target injection amount and a predetermined reference energization time is obtained as a differential energization time learning value, and the energization time of the minute injection is determined by the difference energization time learning value. a minute injection amount correction section that performs correction;
a first angular velocity that obtains a relationship between an angular velocity fluctuation amount of the crankshaft caused by a corrected microinjection, which is a microinjection corrected by the differential energization time learning value obtained in the microinjection amount correction unit, and the engine rotation speed; A fluctuation amount acquisition unit,
A second angular velocity fluctuation that performs the corrected micro-injection while changing the energization start timing to the fuel injection valve, and obtains the relationship between the energization start timing, the angular velocity fluctuation amount of the crankshaft, and the engine rotation speed at that time. A quantity acquisition unit;
The relationship between the angular velocity fluctuation amount of the crankshaft and the engine rotation speed acquired by the first angular velocity fluctuation amount acquisition unit, and the energization start timing and the angular velocity of the crankshaft acquired by the second angular velocity fluctuation amount acquisition unit The relationship between the energization start timing and the angular velocity fluctuation amount of the crankshaft, which excludes a deviation in the angular velocity fluctuation amount of the crankshaft caused by the difference in the engine rotation speed, based on the relationship between the fluctuation amount and the engine rotation speed. an engine rotation speed influence correction section that obtains the
Based on the relationship between the energization start timing and the angular velocity fluctuation amount of the crankshaft acquired by the engine rotation speed influence correction unit, the maximum value of the angular velocity fluctuation amount of the crankshaft and the angular velocity fluctuation amount of the crankshaft are an angular velocity variation maximum value acquisition unit that acquires the energization start timing that is the maximum value;
Based on the energization start timing at which the angular velocity variation of the crankshaft reaches the maximum value, the fuel for each cylinder is adjusted such that the angular velocity variation of the crankshaft due to fuel injection in each cylinder reaches the maximum value. an energization start timing correction unit that makes fuel injection start timing constant for each of the cylinders by correcting the energization start timing for the injector;
including fuel injection control equipment. The energization start timing correction section adjusts each energization start timing based on the amount of deviation between the reference energization start timing stored in advance in the electronic control unit and the energization start timing at which the angular velocity fluctuation amount of the crankshaft reaches the maximum value . The fuel injection control device according to claim 1 , wherein the energization start timing for the fuel injection valve of each cylinder is corrected so that the angular velocity fluctuation amount of the crankshaft due to fuel injection in the cylinder becomes the maximum value. . The energization start timing correction unit corrects the energization start timing of the reference cylinder so that the angular velocity fluctuation amount of the crankshaft in a predetermined reference cylinder becomes the maximum value, and
The energization start timing at which the angular velocity variation of the crankshaft in the reference cylinder reaches the maximum value, and the energization start timing at which the angular velocity variation of the crankshaft reaches the maximum value in other cylinders other than the reference cylinder. and correcting the energization start timing for the fuel injection valve of each of the other cylinders so that the amount of angular velocity fluctuation of the crankshaft due to fuel injection in each of the other cylinders becomes the maximum value, based on the amount of deviation. The fuel injection control device according to claim 1. If the maximum value of the angular velocity variation of the crankshaft acquired by the maximum angular velocity variation acquisition unit is not within a target range, the maximum value of the angular velocity variation of the crankshaft is within the target range. 4. The fuel injection control device according to claim 1, further comprising a minute injection amount re-correction section that further corrects the differential energization time learning value calculated by the minute injection amount correction section. Any one of claims 1 to 4, further comprising a corrected energization time changing unit that sets the energization end timing in the corrected micro-injection by correcting the energization end timing before the correction in the micro-injection using the differential energization time learning value. 2. The fuel injection control device according to item 1. A method of controlling a fuel injection control device for an engine having a plurality of cylinders, the method comprising:
The minute injection amount correction unit estimates that the fuel was injected during the minute injection based on the amount of fluctuation in the angular velocity of the crankshaft when the minute injection, which is fuel injection with a minute injection amount, is executed multiple times while changing the energization time. Calculate the estimated injection amount, obtain the difference between the energization time when the estimated injection amount becomes the target injection amount and a predetermined reference energization time as a differential energization time learning value, and use the differential energization time learning value. a step of correcting the energization time of the micro-injection;
The first angular velocity fluctuation amount acquisition unit determines the angular velocity fluctuation amount of the crankshaft and the engine rotation speed caused by the corrected minute injection, which is the minute injection corrected by the differential energization time learning value acquired by the minute injection amount correction unit. a step of obtaining a relationship with
The second angular velocity fluctuation amount acquisition unit performs the corrected minute injection while changing the energization start timing to the fuel injector, and at that time, the energization start timing, the angular velocity fluctuation amount of the crankshaft, and the engine rotation speed are determined . a step of obtaining the relationship of
The engine rotational speed influence correction unit calculates the relationship between the angular velocity fluctuation amount of the crankshaft and the engine rotational speed acquired by the first angular velocity fluctuation amount acquisition unit, and the energization acquired by the second angular velocity fluctuation amount acquisition unit. Based on the relationship between the start timing, the angular velocity variation of the crankshaft, and the engine rotational speed, the energization start timing and the crankshaft are determined by eliminating a deviation in the angular velocity variation of the crankshaft caused by the difference in the engine rotational speed. a step of obtaining a relationship with the angular velocity fluctuation amount of the shaft ;
An angular velocity variation maximum value acquisition unit obtains a maximum value of the angular velocity variation of the crankshaft based on the relationship between the energization start timing and the angular velocity variation of the crankshaft acquired by the engine rotation speed influence correction unit , and acquiring the energization start timing at which the angular velocity fluctuation amount of the crankshaft reaches the maximum value ; the energization start timing correcting unit determines each of the energization start timings at which the angular velocity fluctuation amount of the crankshaft reaches the maximum value; Starting fuel injection for each cylinder by correcting the energization start timing for the fuel injector for each cylinder so that the angular velocity fluctuation amount of the crankshaft due to fuel injection in the cylinder becomes the maximum value . a step of keeping the timing constant;
A control method for a fuel injection control device, including:

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