JP2017106419A - Fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device that can reduce fuel noise even when having a simple configuration.SOLUTION: In a fuel injection control device, correction amount for correcting a variation of a fuel injection valve 15 caused by a device difference is stored in a memory 80b beforehand. Specifically, the correction amount is a value for correcting an instruction valve opening time so that actual injection amount at instruction valve opening time corresponds to instruction injection amount. In addition, the correction amount is correction amount relative to instruction injection amount to a position where a needle 15a reaches a maximum injection rate after injection into a cylinder is started. By using the correction amount, the instruction valve opening time is corrected, and based on the corrected instruction correction valve opening time, instruction fuel pressure is corrected. Therefore, since the instruction injection amount during the operation of the needle 15a is corrected, an error of instruction valve opening speed is corrected. Due to this, a device difference of the injection rate is corrected, so that a variation of the injection rate caused by the device difference can be reduced.SELECTED DRAWING: Figure 16

Description

  The present invention relates to a fuel injection control device that controls a fuel injection valve used for fuel injection into a combustion chamber of an internal combustion engine.

  When the injection rate is controlled by the fuel injection device, combustion noise can be reduced. Specifically, when the gradient of the injection rate is made gentle, the change in the heat generation rate becomes gentle, so that combustion noise can be reduced.

  A technique for controlling the inclination of the injection rate is disclosed in Patent Document 1. In the fuel injection device described in Patent Document 1, an electrostrictive actuator that controls the lift amount by voltage is used to vary the needle speed and control the gradient of the injection rate.

Japanese Patent Laid-Open No. 11-200981

  As in the fuel injection device described in Patent Document 1 described above, if the degree of freedom in adjusting the injection rate inclination is set too high, the structure becomes complicated and the productivity and cost effectiveness deteriorate. In view of this, it is conceivable to adopt a simple configuration in which the degree of freedom of adjustment of the gradient of the injection rate is two or three. In such a case, on the contrary, fine adjustment of the inclination of the injection rate becomes impossible, and there has been a problem that combustion noise deteriorates due to the difference in the fuel injection device.

  Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection control device that can reduce fuel noise even with a simple configuration.

  The present invention employs the following technical means in order to achieve the aforementioned object.

  The present invention corrects the valve opening time based on the storage unit (80b) storing the correction amount for correcting the valve opening time, and the correction amount stored in the storage unit, and opens the valve after the correction. A correction unit (85f) that corrects the indicated fuel pressure according to time, an opening and closing that controls the speed adjusting unit based on the indicated valve opening speed, the indicated corrected fuel pressure corrected by the correcting unit, and the indicated corrected valve opening time. And a control unit (80), and the correction amount is instructed to open the valve so that the actual injection amount that has been injected by the fuel injection valve during the instructed valve opening time from the valve opening time instructing unit matches the instructed injection amount. This is a fuel injection control device that is a value that corrects the time and is a correction amount for the commanded injection amount from the start of injection into the cylinder to the position at which the valve body reaches the maximum injection rate.

  According to the present invention as described above, the storage unit stores in advance a correction amount for correcting variation in machine difference. Specifically, the correction amount is a value for correcting the command valve opening time so that the actual injection amount at the command valve opening time matches the command injection amount. Further, the correction amount is a correction amount with respect to the commanded injection amount from the start of injection into the cylinder to the position where the valve body reaches the maximum injection rate. Then, the command valve opening time is corrected using the correction amount, and the command fuel pressure is corrected by the corrected command correction valve opening time. Therefore, since the command injection amount during the operation of the valve body is corrected, the error of the command valve opening speed is corrected. As a result, the machine difference in the injection rate is corrected, so that variations in the injection rate due to the machine difference can be reduced. Therefore, it is possible to realize an injection rate with reduced combustion noise by controlling the injection rate at a plurality of stages and not by controlling the injection rate with high accuracy. Even with such a simple fuel injection device, combustion noise can be reduced.

  In addition, the code | symbol in the bracket | parenthesis of each above-mentioned means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a figure explaining the combustion system of the internal combustion engine of a 1st embodiment. It is a figure explaining the piping composition of an internal-combustion engine. It is a figure explaining operation | movement of a needle. It is a graph explaining an injection rate. It is a graph explaining a heat release rate. It is a graph which shows the relationship between an initial stage injection rate and performance. It is a graph explaining a heat release rate. It is a graph which shows the relationship between the injection rate height and performance. It is a graph which shows the relationship between electricity supply time and injection quantity. It is a graph which shows the relationship between electricity supply time and injection quantity. It is a flowchart which shows a learning process. It is a figure which shows the map of correction amount. It is a flowchart which shows a fuel-injection process. It is a graph for demonstrating the injection quantity Qadj for correction | amendment. It is a graph for calculating | requiring correction amount (DELTA) Pc. It is a graph which shows the waveform of an injection rate. It is a figure which shows the relationship between pilot injection quantity and performance. It is a figure which shows the relationship between an after injection amount and performance. It is a flowchart which shows the fuel-injection control of 2nd Embodiment. It is a flowchart which shows the fuel-injection control of 3rd Embodiment. It is a graph which shows a basic combustion speed. It is a graph which shows the relationship between an injection pressure and a correction coefficient.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described using a plurality of embodiments with reference to the drawings. In some embodiments, portions corresponding to the matters described in the preceding embodiments may be given the same reference numerals, or one letter may be added to the preceding reference numerals, and overlapping descriptions may be omitted. In addition, when a part of the configuration is described in each embodiment, the other parts of the configuration are the same as those of the embodiment described in advance. In addition to the combination of parts specifically described in each embodiment, the embodiments may be partially combined as long as the combination does not hinder the combination.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The fuel injection control device of the first embodiment is provided by an electronic control device (hereinafter also referred to as “ECU”) 80 shown in FIG. The ECU 80 executes a program stored in the memory 80b, which is a storage medium, and controls each unit. The ECU 80 includes at least one arithmetic processing unit (CPU) and a storage medium that stores programs and data. The ECU 80 is realized by, for example, a microcomputer (hereinafter, also referred to as “microcomputer”) 80a including a computer-readable storage medium. The memory 80b is a non-transitional tangible storage medium that stores a computer-readable program and data in a non-temporary manner. The memory 80b is realized by a semiconductor memory or a magnetic disk.

  The microcomputer 80a controls the operation of the fuel injection valve 15, the fuel pump 15p, the EGR valve 17a, the temperature control valve 17d, and the like included in the combustion system by executing a predetermined program stored in the memory 80b. By these controls, the combustion state in the internal combustion engine 10 included in the combustion system is controlled to a desired state. The combustion system and ECU 80 are mounted on the vehicle. The vehicle travels using the output of the internal combustion engine 10 as a drive source.

  The internal combustion engine 10 includes a cylinder block 11, a cylinder head 12, a piston 13, and the like. The cylinder head 12 is provided with an intake valve 14in, an exhaust valve 14ex, a fuel injection valve 15, and an in-cylinder pressure sensor 21 serving as a combustion sensor.

The internal combustion engine 10 is a compression self-ignition diesel engine, and has a plurality of cylinders 110 as shown in FIG. A fuel injection valve 15 is attached to each cylinder 110, and fuel injected from the fuel injection valve 15 into the cylinder 110 is compressed by a piston 13 (not shown) and self-ignited and combusted. In the example of FIG. 2, it is a four-cylinder engine.
The fuel pump 15p pumps the fuel in the fuel tank to the common rail 15c. The common rail 15c functions as a pressure accumulating unit that stores fuel supplied to the fuel injection valve 15 in a high pressure state. As the ECU 80 controls the operation of the fuel pump 15p, the fuel in the common rail 15c is stored in the common rail 15c while being maintained at the target pressure Ptrg. The common rail 15c distributes the accumulated fuel to the fuel injection valve 15 of each cylinder 110.

  The fuel injection valve 15 has a needle 15a that is a valve body, and directly injects fuel into the cylinder 110 of the internal combustion engine 10 by opening and closing the needle 15a. The fuel injected from the fuel injection valve 15 is mixed with the intake air in the combustion chamber 11a to form an air-fuel mixture, and the air-fuel mixture is compressed by the piston 13 and self-ignited. Therefore, the internal combustion engine 10 is a compression self-ignition type diesel engine, and light oil is used as fuel.

  The fuel injection valve 15 is configured by accommodating an actuator 15b and a needle 15a inside a body 15d. When the ECU 80 turns on the energization of the actuator 15b, the actuator 15b opens a leak passage in a back pressure chamber (not shown). Then, as the back pressure is lowered, the needle 15a is opened to open the nozzle hole 15e formed in the body 15d, and fuel is injected from the nozzle hole 15e. When energization is turned off, the needle 15a is closed to stop fuel injection.

  The actuator 15b is configured to be able to adjust the valve opening speed of the needle 15a over a plurality of stages. The actuator 15b includes a piezo stack, for example. The piezo stack is a stacked body in which layers called PZT (PbZrTiO 3) and thin electrode layers are alternately stacked, and expands and contracts by applying a voltage due to the reverse piezoelectric effect which is a characteristic of the piezo element. The actuator 15b controls the position of the needle 15a using the displacement of the piezo stack.

  For example, in a state where no voltage is applied to the piezo stack, as shown in FIG. 3, the needle 15a is closed and fuel injection is not performed. When a voltage is applied to the piezo stack, the piezo stack expands, and with the expansion as a power, the needle 15a is pushed up, and fuel injection is started as shown in FIG. When the voltage applied to the piezo stack is turned off, it discharges and the piezo stack contracts. As a result, the needle 15a is pushed down and fuel injection stops. By controlling the voltage supplied to the actuator 15b, the amount of expansion of the piezo stack can be controlled. Therefore, by controlling the voltage, the valve opening speed of the needle 15a can be adjusted in a plurality of stages. Therefore, the actuator 15b functions as a speed adjustment unit.

  The internal combustion engine 10 further includes an intake pipe 16in, an intake distribution pipe 160, an exhaust pipe 16ex, an exhaust collecting pipe 161, and an EGR pipe 17, as shown in FIG. An intake pipe 160 and an exhaust collecting pipe 161 are connected to the intake port 12in and the exhaust port 12ex formed in the cylinder head 12. The intake pipe 16 in distributes intake air (fresh air) toward the cylinder 110. The intake pipe 160 is connected to the downstream end of the intake pipe 16in and distributes intake air to the plurality of cylinders 110. The exhaust collecting pipe 161 collects the exhaust discharged from each cylinder 110. The exhaust pipe 16ex distributes the collected exhaust to an exhaust purification device (not shown).

  The EGR pipe 17 constitutes an exhaust gas recirculation device, and a part of the exhaust gas is recirculated as EGR gas and introduced into the intake air. The EGR gas is also called a reflux gas. The downstream end of the EGR pipe 17 is connected to the intake distribution pipe 160 or the intake pipe 16in. Thus, the EGR gas cooled by the EGR cooler 17b is mixed with fresh air, and the intake air mixed with the EGR gas and fresh air is distributed to each cylinder 110 by the intake air distribution pipe 160.

  An EGR valve 17 a is attached to the EGR pipe 17. When the ECU 80 controls the operation of the EGR valve 17a, the opening degree of the EGR pipe 17 is controlled, and the EGR amount that is the flow rate of the EGR gas is controlled. Therefore, the ECU 80 functions as an exhaust control unit that controls the recirculation amount by the exhaust gas recirculation device.

  Further, an EGR cooler 17b for cooling the EGR gas, a bypass pipe 17c, and a temperature control valve 17d are attached to the EGR pipe 17 upstream of the EGR valve 17a. The bypass pipe 17c forms a bypass channel through which EGR gas bypasses the EGR cooler 17b. The temperature control valve 17d adjusts the opening degree of the bypass flow path, thereby adjusting the ratio of the EGR gas flowing through the EGR cooler 17b and the EGR gas flowing through the bypass flow path. As a result, the temperature of the EGR gas flowing into the intake pipe 16in is adjusted.

  Here, the intake air flowing into the intake port 12in includes fresh air and EGR gas that are external air flowing in from the intake pipe 16in. Therefore, adjusting the temperature of the EGR gas by the temperature control valve 17d corresponds to adjusting the intake manifold temperature that is the temperature of the intake air flowing into the intake port 12in. Further, as shown in FIG. 2, a throttle valve 29 is attached to the intake pipe 16in, and the flow rate of fresh air contained in the intake air is adjusted by adjusting the opening of the throttle valve 29.

  The shape of the intake pipe 160 is set so that the intake air is evenly distributed to each cylinder 110. However, it is difficult to evenly distribute the EGR gas to the respective cylinders 110, and distribution variation occurs due to the position where the downstream end of the EGR pipe 17 is connected, the shape of the intake pipe 160, and the like. . That is, the EGR gas concentration of the intake air flowing into each cylinder 110 varies. The arrows in FIG. 2 indicate the flow of EGR gas flowing into each cylinder 110. In the example of FIG. 2, the layout is such that the EGR gas is most likely to flow into the cylinder 110 closest to the intake pipe 16in.

  The ECU 80 receives detection signals from various sensors such as the in-cylinder pressure sensor 21, the oxygen concentration sensor 22, the rail pressure sensor 23, the crank angle sensor 24, and the accelerator pedal sensor 25.

  The in-cylinder pressure sensor 21 outputs a detection signal corresponding to the in-cylinder pressure that is the pressure in the combustion chamber 11a. The in-cylinder pressure sensor 21 includes a temperature detection element 21a in addition to the pressure detection element, and also outputs a detection signal corresponding to the in-cylinder temperature that is the temperature of the combustion chamber 11a.

  The oxygen concentration sensor 22 is attached to the intake pipe 16in, and outputs a detection signal corresponding to the oxygen concentration in the intake air. The intake air to be detected is a mixture of fresh air and EGR gas. The rail pressure sensor 23 is attached to the common rail 15c, and outputs a detection signal corresponding to the rail pressure that is the pressure of the accumulated fuel.

  The crank angle sensor 24 outputs a detection signal corresponding to the rotational speed of the crankshaft that is rotationally driven by the piston 13 and corresponding to the engine rotational speed that is the rotational speed of the crankshaft per unit time. The accelerator pedal sensor 25 outputs a detection signal corresponding to the amount of depression of the accelerator pedal that is depressed by the vehicle driver, that is, the engine load.

  The ECU 80 controls the operation of the fuel injection valve 15, the fuel pump 15p, the EGR valve 17a, and the temperature control valve 17d based on these detection signals. Thereby, the fuel injection start timing, the injection amount, the injection pressure, the EGR gas flow rate, and the intake manifold temperature are controlled.

  The microcomputer 80a when controlling the operation of the fuel injection valve 15 functions as an injection control unit 85a that controls the fuel injection start timing, the injection amount, and the number of injection stages related to multistage injection. Therefore, the injection control unit 85a functions as a fuel injection control device that controls the fuel injection device. The microcomputer 80a when controlling the operation of the fuel pump 15p functions as a fuel pressure control unit 85b that controls the injection pressure. The microcomputer 80a when controlling the operation of the EGR valve 17a functions as an EGR control unit 85c for controlling the EGR gas flow rate. The microcomputer 80a when controlling the operation of the temperature control valve 17d functions as an intake manifold temperature control unit 85e that controls the intake manifold temperature.

  The upper part of FIG. 4 shows the voltage supplied to the actuator 15b. Energization to the fuel injection valve 15 is controlled according to the voltage waveform. Specifically, energization is started at time t1, and energization is continued during energization time Tq. In short, the injection start timing is controlled by the ON timing. Further, the injection period is controlled by the energization time Tq, and consequently the injection amount is controlled.

  The middle part of FIG. 4 shows the position of the needle 15a. There is a time lag from the time t1 when the energization starts to the time t2 when the needle 15a rises. There is also a time lag from when the energization ends until the needle 15a actually reaches the reference position.

  The lower part of FIG. 4 shows the change in the state of fuel injection from the nozzle hole 15e. Specifically, it shows the change in the injection amount of fuel injected per unit time, that is, the injection rate. As illustrated, a time lag occurs as in the needle position, and the amount of change in the needle position, that is, the valve opening speed of the needle 15a and the injection rate are correlated. When the valve opening speed is high, the change in the injection rate becomes large, and when the valve opening speed is low, the change in the injection rate becomes small. The period Tq1 during which injection is actually performed is controlled by the energization time Tq.

  Next, the relationship between the injection rate and the heat generation rate will be described with reference to FIG. The injection shown in FIG. 5 is multi-stage injection, and pilot injection is performed before main injection. In the upper part of FIG. 5, pilot injection has the same injection rate, and three patterns of main injection are shown. In the main injection, the valve opening speed changes in two stages until the needle 15a reaches the maximum displacement position. And the valve opening speed of the first half is larger than the valve opening speed of the second half. In FIG. 5, the valve opening speed at the latter stage is changed to three patterns, and the heat generation rate at that time is shown in the lower stage of FIG.

  The lower part of FIG. 5 shows the change in the combustion state of the injected fuel in the combustion chamber 11a. Specifically, it shows the change in the amount of heat per unit time, that is, the heat generation rate, which occurs when the mixture of injected fuel and intake air undergoes self-ignition combustion. As shown in the figure, there is a time lag from the start of injection to the time when combustion is actually started. The heat release rate changes more as the valve opening speed is higher.

  Next, the relationship between the injection rate, fuel consumption, smoke, and fuel noise will be described with reference to FIG. FIG. 6 corresponds to the valve opening speeds of the three patterns shown in FIG. 5. For example, an injection rate with the highest valve opening speed is excellent in all of fuel consumption, smoke, and combustion noise. However, at the valve opening speed indicated by the solid line in FIG. 5, the combustion noise is worse than the allowable limit. Therefore, if the valve opening speed differs depending on the machine difference, the combustion noise may exceed the allowable limit, so control of the valve opening speed is important.

  Next, the case where the valve opening speed is the same will be described with reference to FIGS. As shown in the upper part of FIG. 7, three patterns of main injection are shown. The main injection has the same injection amount and the same valve opening speed, but the maximum injection rate to be maintained is different. Then, as shown in the lower part of FIG. 7, the heat generation rate is equal to each other in the three patterns because the slopes of the heat generation rates are equal to each other as shown in FIG. 8 where the injection rate corresponds to the height c. is there. The waveform with the highest injection rate is excellent in fuel consumption and smoke. In other words, if the valve opening speed is the same, a higher injection rate is preferable.

  Next, the relationship between the injection amount and the energization time will be described with reference to FIGS. 9 and 10. FIG. 9 shows three patterns of valve opening speed waveforms. The injection amount and the energization time are in a directly proportional relationship. And when it is the same energization time, it turns out that the amount of injection is so large that the valve opening speed is quick.

  As shown in FIG. 10, an error occurs due to a machine difference in the actual injection with respect to a waveform having no theoretical error between the energization time and the injection amount. In order to maintain the injection amount, the energization time may be adjusted. In other words, the error can be corrected by adjusting the energization time.

  Therefore, control for learning a correction amount for correcting an error will be described with reference to FIGS. 11 and 12. The flow shown in FIG. 11 is performed by the ECU 80 at the time of factory shipment, for example. When the learning process shown in FIG. 11 is started by a user's instruction, in step S11, the injection pressure to be learned is set, and the process proceeds to step S12. In step S12, the target injection amount to be learned is set, and the process proceeds to step S13. In step S13, the valve opening speed to be learned, that is, the needle raising speed to be learned is set, and the process proceeds to step S14.

  In step S14, an energization period is calculated from the set injection pressure and target injection amount, and the process proceeds to step S15. In step S15, the actual injection amount injected over the energization period calculated with the set injection pressure is measured, and the process proceeds to step S16.

  In step S16, it is determined whether or not the deviation between the actual injection amount and the injection amount without error is within a predetermined value. If it is within the predetermined value, the process proceeds to step S17, and if not within the predetermined value, the process proceeds to step S18. Move. In step S18, the energization period is finely adjusted, and the process returns to step S15.

  In step S17, since the deviation is within the predetermined value, the adjustment amount of the energization period is stored in the memory 80b as a storage unit, and the process proceeds to step S19. The adjustment amount of the energization period is a correction amount, and is a value for correcting the command valve opening time so that the actual injection amount that is injected by the fuel injection valve 15 during the command valve opening time matches the command injection amount.

  In step S19, it is determined whether learning for the needle ascending speed is completed. If learning is completed, the process proceeds to step S110. If learning is not completed, the process returns to step S13. Thus, a correction amount that is an adjustment amount is stored for the valve opening speed used for the control.

  In step S110, it is determined whether learning for the injection amount is completed. If learning is completed, the process proceeds to step S111. If learning is not completed, the process returns to step S12. Thus, the correction amount is stored for the injection amount used for control.

  In step S111, it is determined whether or not learning for the injection pressure has been completed. If learning has been completed, this flow is terminated. If learning has not been completed, the process returns to step S11. Thereby, the correction amount is stored for the injection pressure used for the control.

  By such learning processing, a map as shown in FIG. 12 is stored in the memory 80b. In the map, for example, for each predetermined injection pressure, a correction amount for a predetermined valve opening speed and a predetermined target injection amount is stored. The valve opening speed is, for example, three stages of High, Mid, and Low.

  Next, fuel injection control using such a correction amount will be described with reference to FIGS. The fuel injection control shown in FIG. 13 is control that is repeatedly performed in a short time while the engine is driven.

  In step S21, the injection amount Q, the injection pressure Pc, and the needle ascending speed mode Md (H, M, L) are calculated based on the detected engine speed and accelerator opening, and the process proceeds to step S22. Here, the ascending speed mode has three patterns. Therefore, in step S22, the ECU 80 functions as a fuel pressure instruction unit that instructs a fuel pressure that is an injection pressure based on an output request to the internal combustion engine 10. Further, by step S22, the ECU 80 also functions as an injection amount instruction unit that instructs a fuel amount that is an injection amount injected from the fuel injection valve 15 based on the output request.

In step S22, the correction injection amount Qadj is calculated based on the injection pressure Pc and the needle ascending speed mode Md, and the process proceeds to step S23. Here, the correction injection amount will be described with reference to FIG. In FIG. 14, as in FIG. 4, the voltage, needle position, and injection rate are shown in the upper three stages. In the lowest stage, the relationship between the injection amount and time is shown, and the injection amount gradually increases as the injection rate increases. The injection amount from when the needle 15a is fully raised to the maximum position is the correction injection amount Qadj. This is shown by the following equation (1).
Qadj = g (Pc, Md) (1)

In step S23, the energization period TQadj is calculated using the following equation (2) from the correction injection amount Qadj, the injection pressure Pc, and the needle ascending speed mode Md, and the process proceeds to step S24. By step S23, the ECU 80 functions as a valve opening time instruction unit for instructing the valve opening time of the needle 15a based on the commanded fuel pressure, the commanded injection amount, and the commanded valve opening speed.
TQadj = f (Qadj, Pc, Md) (2)

In step S24, for each of the injection pressures Pc−Δ and Pc + Δ, the negative energization period TQm and the positive energization period TQp are calculated by Expressions (3) and (4) in the correction injection amount Qadj and the needle ascending speed mode Md. Further, for each of the injection pressures Pc−Δ and Pc + Δ, the correction injection amount Qadj, the negative energization correction amount ΔTQm, and the positive energization correction amount ΔTQp in the needle ascending speed mode Md are stored as shown in the equations (5) and (6). Read from 80b, then go to step S25. Here, Δ is a fixed value.
TQm = f (Qadj, Pc−Δ, Md) (3)
TQp = f (Qadj, Pc + Δ, Md) (4)
ΔTQm = h (Qadj, Pc−Δ, Md) (5)
ΔTQp = h (Qadj, Pc + Δ, Md) (6)

In step S25, a pressure correction amount ΔPc is calculated, and the process proceeds to step S26. Here, a method of calculating the pressure correction amount ΔPc will be described with reference to FIG. In order to calculate the pressure correction amount ΔPc corresponding to the calculated energization period TQadj, the energization period and the pressure correction amount are assumed to change by a linear function as shown in FIG. Specifically, it is obtained by Expression (7) which is an interpolation expression based on FIG.

In step S26, the energization period TQ is calculated using the equation (8) with the corrected injection pressure Pc + ΔPc, needle ascending speed mode Md, and injection amount Q. Further, the energization period correction amount ΔTQ is read from the memory 80b as shown in the equation (9) by the corrected injection pressure Pc + ΔPc, needle ascending speed mode Md, and injection amount Q, and the process proceeds to step S27. Through step S25 and step S26, the ECU 80 corrects the valve opening time based on the correction amount stored in the memory 80b, and corrects the indicated fuel pressure according to the corrected valve opening time. Function as.
TQ = f (Q, Pc + ΔPc, Md) (8)
ΔTQ = h (Q, Pc + ΔPc, Md) (9)

  In step S27, injection is performed with the corrected injection pressure Pc + ΔPc, the needle ascending speed mode Md, and the corrected energization period TQ + ΔTQ, and this flow ends. By step S27, the ECU 80 functions as an open / close control unit that controls the speed adjustment unit based on the command valve opening speed, the command correction fuel pressure corrected by the correction unit 85f, and the command correction valve opening time.

  Accordingly, the ECU 80 controls the common rail 15c based on the commanded fuel pressure, and thus functions as a fuel pressure control unit that controls the fuel pressure. Further, since the ECU 80 controls the actuator 15b based on the output request, the ECU 80 functions as a valve opening speed instruction unit that instructs the valve opening speed of the needle 15a.

  By such fuel injection control, correction is made from the state before pressure correction as shown in FIG. In the corrected injection rate waveform, the correction amount is used so that the needle ascending speed mode Md becomes equal. As a result, the injection period is shorter than before the correction, but the maximum value of the injection rate is increased accordingly to secure the injection amount. As a result, the corrected waveform is brought closer to the waveform with no error, so that combustion noise is prevented from increasing.

  On the other hand, in the comparative example, correction for shortening the injection period is performed without considering the injection rate. As a result, since the injection rate becomes moderate, the combustion noise becomes smaller than necessary, and as shown in FIG. 6, smoke and fuel consumption are deteriorated.

  As described above, in the fuel injection control apparatus according to the present embodiment, the memory 80b stores in advance a correction amount for correcting variations in machine differences of the fuel injection valves 15. Specifically, the correction amount is a value for correcting the command valve opening time so that the actual injection amount at the command valve opening time matches the command injection amount. Furthermore, the correction amount is a correction amount for the command injection amount when the needle 15a is at a position equal to or less than the displacement amount at which the injection rate into the cylinder, which is injected from the fuel injection valve 15, reaches the maximum. In other words, the correction amount is a correction amount for the instructed injection amount from the start of injection into the cylinder to the position where the needle 15a reaches the maximum injection rate. Then, the command valve opening time is corrected using the correction amount, and the command fuel pressure is corrected by the corrected command correction valve opening time. Therefore, since the command injection amount during operation of the needle 15a is corrected, the error of the command valve opening speed is corrected. As a result, the machine difference in the injection rate is corrected, so that variations in the injection rate due to the machine difference can be reduced. Therefore, the injection rate with reduced combustion noise can be realized by the control of the injection rate in a plurality of stages, in this embodiment, in two stages, and the valve opening time control, instead of the highly accurate control. Even with such a simple fuel injection device, combustion noise can be reduced.

  Further, in the present embodiment, the actuator 15b adjusts the valve opening speed in two stages, and the ECU 80 sets the valve opening speed in the first half to the valve opening speed in the latter half of the valve opening speed until the displacement of the needle 15a reaches the maximum. It is controlled so as to be larger. As a result, the first half can quickly reduce the occurrence time of the sheet squeeze, and the second half can suppress combustion noise with a gentle rise. Since the time during which the sheet restriction is formed is shortened, the period during which the injected fuel having a relatively large particle diameter is injected is shortened, and the atomization of the injected fuel can be improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that fuel injection control is performed in multistage injection. Multi-stage injection refers to injecting fuel a plurality of times in one combustion cycle in the same cylinder 110. For multiple injections, main injection for exerting combustion torque, pilot injection for injecting a smaller amount of fuel than main injection before main injection, and a smaller amount of fuel than main injection are injected after main injection After-injection is included. NOx reduction can be achieved by pilot combustion related to pilot injection. The amount of smoke can be reduced by after-combustion related to after-injection.

  Next, the relationship between the pilot injection amount and the performance will be described with reference to FIG. When the pilot injection amount is increased as indicated by a broken line, the main injection amount is decreased. As a result, the heat generation rate increases gently. When the pilot injection amount is increased, it becomes too quiet, the combustion noise is worsened, and the smoke is also worsened.

  Next, the relationship between the after injection amount and the performance will be described with reference to FIG. When the after injection amount is increased as indicated by a broken line, the main injection amount is decreased. This increases the change in heat generation rate. Increasing the after-injection amount improves the smoke amount, but worsens the fuel consumption.

  Next, fuel injection control in such multistage injection will be described with reference to FIG. The fuel injection control shown in FIG. 19 is control that is repeatedly performed in a short time while the engine is driven.

  In step S31, as in step S21, the injection amount Q, the pilot injection amount Qpl, the after injection amount Qaf, the injection pressure Pc, and the needle ascending speed mode Md (H, M, L) is calculated, and the process proceeds to step S32. The pilot injection amount Qpl and the after injection amount Qaf are set so that the combustion noise falls within a predetermined range.

  In step S32, as in step S22, the correction injection amount Qadj is calculated based on the injection pressure Pc and the needle ascending speed mode Md, and the process proceeds to step S33. In step S33, as in step S23, the energization period TQadj is calculated using equation (2) from the correction injection amount Qadj, the injection pressure Pc, and the needle ascending speed mode Md, and the process proceeds to step S34.

In step S34, as in step S24, the correction energization amount Qadj and the negative energization period TQm and the plus energization period TQp are calculated for the injection pressures Pc−Δ and Pc + Δ, respectively, using the equations (3) and (4). ). For each of the injection pressures Pc−Δ and Pc + Δ, for each cylinder 110, the correction injection amount Qadj, the negative energization correction amount ΔTQm (i) and the positive energization correction amount ΔTQp (i) in the needle ascending speed mode Md 10) and the equation (11), the data is read from the memory 80b, and the process proceeds to step S35. Here, i is the number 1 to 4 of the cylinder 110. Therefore, the correction amount is stored for each of the plurality of fuel injection valves 15 in the memory 80b.
ΔTQm (i) = h_i (Qadj, Pc−Δ, Md) (10)
ΔTQp (i) = h_i (Qadj, Pc + Δ, Md) (11)

  In step S35, as in step S25, a pressure correction amount ΔPc (i) is calculated for each cylinder 110, and the process proceeds to step S36. By step S36, the ECU 80 functions as a correction amount selection unit that selects the fuel injection valve 15 having the smallest correction amount. In step S36, the minimum value ΔPcMin of ΔPc (i) is calculated, and the process proceeds to step S37.

In step S37, the pilot injection correction amount ΔQpl (i) is calculated using the equation (12) based on the pressure deviation ΔPc (i) −ΔPcMin and the needle ascending speed mode Md, and the after injection correction amount ΔQaf (i) is calculated using the equation (12). Calculate using (13), then go to Step S38. Since there is an error in the pressure, the correction amount is calculated in order to correct the pilot injection amount and the after injection amount as well.
ΔQpl (i) = x (ΔPc (i) −ΔPcMin, Md) (12)
ΔQaf (i) = y (ΔPc (i) −ΔPcMin, Md) (13)

In step S38, the main injection amount Qm (i) is calculated using equation (14), and the process proceeds to step S39.
Qm (i) = Q−Qpl (i) −Qaf (i) (14)

  In step S39, as in step S26, the energization period of each stage is determined by the injection pressure Pc + ΔPcMin, the needle ascending speed mode Md, the pilot injection amount Qpl (i), the main injection amount Qm (i), and the after injection amount Qaf (i). The energization period correction amount is calculated, and the process proceeds to step S310.

  In step S310, as in step S27, the injection is performed with the corrected injection pressure Pc + ΔPcMin, the needle ascending speed mode Md, and the corrected energizing period, and this flow ends.

  As described above, in the present embodiment, the ECU 80 corrects at least one of the pilot injection amount and the after injection amount based on the deviation between the selected correction amount and the correction amount in each fuel injection valve 15. It functions as an injection amount correction unit. As a result, not only in the main injection but also in the pilot injection and the after injection, it is possible to approach a waveform having no error. As a result, the pilot injection amount and the after injection amount can be corrected to such an amount that the combustion noise falls within a predetermined range. Therefore, it is possible to improve the fuel consumption and suppress the generation of smoke while suppressing the deterioration of the combustion noise.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that fuel injection control is performed in consideration of the combustion speed for each cylinder 110. The fuel injection control considering such combustion speed will be described with reference to FIG. The fuel injection control shown in FIG. 20 is control that is repeatedly performed in a short time while the engine is driven.

  In step S41, as in step S21, the injection amount Q, the injection pressure Pc, and the needle ascending speed mode Md (H, M, L) are calculated based on the detected engine speed and accelerator opening, and the process proceeds to step S42. .

  In step S42, as in step S22, the correction injection amount Qadj is calculated based on the injection pressure Pc and the needle ascending speed mode Md, and the process proceeds to step S43.

  In step S43, as in step S23, the energization period TQadj is calculated using equation (2) from the correction injection amount Qadj, the injection pressure Pc, and the needle ascending speed mode Md, and the process proceeds to step S44.

  In step S44, as in step S34, the correction energization amount Qadj and the negative energization period TQm and the plus energization period TQp are calculated for the injection pressures Pc−Δ and Pc + Δ, respectively, using the equations (3) and (4). ). For each of the injection pressures Pc−Δ and Pc + Δ, for each cylinder 110, the correction injection amount Qadj, the negative energization correction amount ΔTQm (i) and the positive energization correction amount ΔTQp (i) in the needle ascending speed mode Md 10) and the expression (11), the data is read from the memory 80b, and the process proceeds to step S45.

  In step S45, as in step S35, a pressure correction amount ΔPc (i) is calculated for each cylinder 110, and the process proceeds to step S46. In step S46, the in-cylinder temperature Tcyl (i) for each cylinder 110 and the in-cylinder O2 concentration O2cyl (i) are calculated, and the process proceeds to step S47.

In step S47, the combustion speed for each cylinder 110 is calculated by the following equation (15), and the process proceeds to step S48.
v (i) = q (Tcyl (i), O2cyl (i)) * r (Pc + ΔPc (i))
... (15)

  The combustion speed can be obtained by multiplying the basic combustion speed and the correction coefficient. The basic combustion speed is determined from the in-cylinder temperature Tcyl and the in-cylinder O2 concentration O2cyl using the map shown in FIG. The map is stored in advance in the memory 80b. The correction coefficient is determined from the relationship with the injection pressure shown in FIG. The relationship between the correction coefficient and the injection pressure is also stored in the memory 80b. Therefore, the combustion speed v (i) can be obtained for each cylinder 110 by the equation (15). By step S47, the ECU 80 functions as the flammability estimation unit 85d that estimates the flammability of the fuel in each cylinder 110 in consideration of the variation amount of the exhaust gas sucked into each cylinder 110 for each cylinder 110.

  In step S48, the cylinder number n that maximizes the combustion speed v (i) is calculated, and the process proceeds to step S49. In step S49, the injection pressure correction amount ΔPcFin is set to the correction amount ΔPc (n) of the cylinder number selected in step S48, and the process proceeds to step S410. By step S410, the ECU 80 functions as a cylinder selection unit that selects the cylinder 110 having the highest combustion speed from the correction amount for each fuel injection valve 15 and the ease of burning by the estimation unit.

  In step S410, the energization period and the energization period correction amount are calculated from the injection pressure Pc + ΔPcFin, the needle ascending speed mode Md, and the injection amount Q, and the process proceeds to step S411.

  In step S411, as in step S310, the injection is performed with the corrected injection pressure Pc + ΔPcFin, the needle ascending speed mode Md, and the corrected energizing period, and this flow is finished.

  In this way, the correction is performed using the correction amount of the cylinder 110 that is most flammable in consideration of the combustion speed. In the flammable cylinder 110, an increase in error has a large influence on combustion noise. Therefore, in this embodiment, the error is corrected by the flammable cylinder 110, so that the combustion noise can be within an appropriate range.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  The structure of the above-described embodiment is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  In the first embodiment described above, the learning process is performed at the time of manufacture, but is not limited to the time of manufacture, and may be performed periodically. For example, it may be performed every predetermined traveling distance, or may be performed every time a predetermined period elapses.

  In the first embodiment described above, the actuator 15b of the fuel injection valve 15 uses a piezo stack, but is not limited to such a configuration. Any configuration may be used as long as the valve opening speed can be switched over a plurality of stages. For example, a configuration may be adopted in which a plurality of pressure chambers having different pressures are provided and the valve opening speed is switched by switching them.

  In the first embodiment described above, the functions realized by the ECU 80 may be realized by hardware and software different from those described above, or a combination thereof. For example, each function such as the correction unit 85f realized by the ECU 80 may be realized by one processor. The ECU 80 may communicate with, for example, another control device, and the other control device may execute part or all of the processing. When the ECU 80 is realized by an electronic circuit, it can be realized by a digital circuit including a large number of logic circuits or an analog circuit.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine 15a ... Needle (valve body) 15b ... Actuator (speed adjustment part)
15c ... Common rail (pressure accumulator) 16ex ... Exhaust pipe 16in ... Intake pipe 17 ... EGR pipe (exhaust gas recirculation device) 17a ... EGR valve 17c ... Bypass pipe 17d ... Temperature control valve 21 ... In-cylinder pressure sensor 22 ... Oxygen concentration sensor 23 ... Rail pressure sensor 24 ... Crank angle sensor 25 ... Accelerator pedal sensor 29 ... Throttle valve 80 ... ECU (fuel pressure indicator, fuel pressure controller, injection amount indicator, valve opening speed indicator, cylinder selector, estimator, exhaust Control unit, correction amount selection unit, opening / closing control unit, valve opening time instruction unit) 80a ... microcomputer 80b ... memory (storage unit) 85f ... correction unit (front and rear injection amount correction unit) 110 ... cylinder 160 ... intake distribution pipe 161 ... Exhaust collecting pipe

Claims (5)

A fuel injection valve (15) having a valve body (15a) for directly injecting fuel into the cylinder (110) of the internal combustion engine (10) by opening and closing the valve body, and high-pressure fuel supplied to the fuel injection valve And a pressure accumulating part (15c) for storing the fuel in the state of the fuel, and a fuel injection device for controlling a fuel injection device comprising: a speed adjusting part (15b) for adjusting the valve opening speed over a plurality of stages within the valve opening time as the valve body is opened and closed A control device,
A fuel pressure indicator (80) for instructing a fuel pressure of the pressure accumulator based on an output request to the internal combustion engine;
A fuel pressure control unit (80) for controlling the fuel pressure of the pressure accumulating unit based on the commanded fuel pressure from the fuel pressure commanding unit;
An injection amount instruction unit (80) for instructing an amount of fuel injected from the fuel injection valve based on the output request;
A valve opening speed instruction section (80) for instructing a valve opening speed of the valve body based on the output request;
A valve opening time instruction unit for instructing the valve opening time based on an instruction fuel pressure from the fuel pressure instruction unit, an instruction injection amount from the injection amount instruction unit, and an instruction valve opening speed from the valve opening speed instruction unit (80)
A storage unit (80b) storing a correction amount for correcting the valve opening time;
A correction unit (85f) that corrects the valve opening time based on the correction amount stored in the storage unit and corrects the indicated fuel pressure according to the valve opening time after correction;
An open / close control unit (80) for controlling the speed adjustment unit based on the command valve opening speed, the command correction fuel pressure corrected by the correction unit, and the command correction valve opening time,
The correction amount is a value for correcting the indicated valve opening time so that the actual injection amount that is injected by the fuel injection valve at the indicated valve opening time from the valve opening time instruction unit matches the indicated injection amount. A fuel injection control device that is a correction amount for the commanded injection amount from a start of injection into the cylinder to a position at which the valve body reaches a maximum injection rate. The internal combustion engine includes a plurality of the cylinders (110) and a plurality of the fuel injection valves (15) corresponding to the plurality of cylinders.
The storage unit stores the correction amount for each of the plurality of fuel injection valves,
The open / close control unit controls the speed adjustment unit to perform pilot injection, main injection, and after injection,
A correction amount selection unit (80) for selecting the smallest one of the plurality of fuel injection valves,
A front-rear injection amount correction unit (85f) that corrects at least one of a pilot injection amount and an after-injection amount based on a deviation between the selected correction amount and the correction amount in each fuel injection valve; The fuel injection control device according to claim 1, further comprising: The internal combustion engine includes a plurality of cylinders (110), a plurality of fuel injection valves (15) corresponding to the plurality of cylinders, and an exhaust gas that introduces a part of the exhaust gas of the internal combustion engine into the intake air to the cylinders. A recirculation device (17),
The storage unit stores the correction amount for each of the plurality of fuel injection valves,
An exhaust control unit (80) for controlling the recirculation amount by the exhaust gas recirculation device;
An estimation unit (80) for estimating the flammability of fuel in each cylinder in consideration of the variation amount of the exhaust gas sucked into each cylinder by the exhaust gas recirculation device for each cylinder;
A cylinder selection unit (80) for selecting the cylinder having the highest combustion speed from the correction amount for each fuel injection valve and the easiness of burning by the estimation unit,
The fuel injection control apparatus according to claim 1, wherein the correction amount used in the correction unit is the correction amount of the cylinder selected by the cylinder selection unit.   The fuel injection control device according to claim 2, wherein the front-rear injection amount correction unit corrects the pilot injection amount and the after-injection amount so that the combustion noise falls within a predetermined range. The speed adjusting unit adjusts the valve opening speed in two stages,
The opening / closing control unit controls the speed adjusting unit so that the valve opening speed in the first half is higher than the valve opening speed in the second half at the valve opening speed until the displacement amount of the valve body reaches the maximum. The fuel injection control device according to any one of claims 1 to 4.

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