WO2017099064A1 - 燃料噴射制御装置 - Google Patents

燃料噴射制御装置 Download PDF

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Publication number
WO2017099064A1
WO2017099064A1 PCT/JP2016/086198 JP2016086198W WO2017099064A1 WO 2017099064 A1 WO2017099064 A1 WO 2017099064A1 JP 2016086198 W JP2016086198 W JP 2016086198W WO 2017099064 A1 WO2017099064 A1 WO 2017099064A1
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WIPO (PCT)
Prior art keywords
injection
injection rate
rate
maximum
fuel
Prior art date
Application number
PCT/JP2016/086198
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English (en)
French (fr)
Japanese (ja)
Inventor
和史 富田
Original Assignee
株式会社デンソー
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Priority to DE112016005640.0T priority Critical patent/DE112016005640B4/de
Publication of WO2017099064A1 publication Critical patent/WO2017099064A1/ja

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/08—Injectors peculiar thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0406—Intake manifold pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/028—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the combustion timing or phasing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present disclosure relates to a fuel injection control device that controls fuel injection into a combustion chamber of an internal combustion engine by a fuel injection valve having a variable injection rate waveform.
  • Diesel engines ignite fuel by compression in the cylinder, so the compression ratio is higher than in gasoline engines, and the in-cylinder pressure generated by combustion is also higher. In order to increase the output, it is necessary to increase the amount of combustion per cycle, which further increases the in-cylinder pressure.
  • the fuel injection amount is controlled so as not to exceed an allowable maximum in-cylinder pressure.
  • the gas density is calculated from the supply manifold pressure and temperature, and the maximum in-cylinder pressure is estimated from the relationship between the gas density and the maximum in-cylinder pressure.
  • the fuel injection amount exceeds the estimated maximum in-cylinder pressure, the fuel injection amount is reduced to reduce the in-cylinder pressure.
  • the fuel injection control described in Patent Document 1 merely controls the fuel injection amount so as not to exceed the maximum in-cylinder pressure, and cannot increase the in-cylinder pressure to increase the output. Further, since the maximum in-cylinder pressure that the engine can tolerate is determined from the strength of the engine itself, it is necessary to increase the engine strength in order to increase the maximum in-cylinder pressure. However, there is a problem that the weight of the engine itself increases due to the strength increase and the manufacturing cost increases.
  • the present disclosure has been made in view of the above-described problems, and an object thereof is to provide a fuel injection control device capable of improving the output while suppressing the in-cylinder pressure to be equal to or less than the maximum in-cylinder pressure.
  • one aspect of the present disclosure includes an ignition acquisition unit that acquires the degree of ignition delay in a cylinder, and any one of a plurality of injection rate waveforms according to an output request to the internal combustion engine.
  • a control unit that controls fuel injection using two injection rate waveforms, and a plurality of injection rate waveforms includes a constant pressure injection rate waveform for controlling the in-cylinder pressure in the combustion chamber to be equal to or less than the maximum in-cylinder pressure.
  • the injection is performed in two stages, the first stage injection and the second stage injection, and includes a constant pressure injection rate waveform in which the rate of change in the injection rate in the first stage injection is larger than the ratio of the change in the second stage injection.
  • the injection rate waveform has a portion in which the injection rate increases from the start of the preceding injection and reaches the maximum injection rate, and a portion in which the injection rate decreases from the maximum injection rate. Injection rate is greater than 0,
  • the control unit has a portion where the injection rate increases from the beginning and reaches the maximum injection rate, and a portion where the injection rate decreases from the maximum injection rate, the control unit, the degree of ignition delay acquired by the ignition acquisition unit is smaller than the threshold, And when the output request
  • the degree of ignition delay when the degree of ignition delay is smaller than the threshold value and the output request to the internal combustion engine is high output, control is performed so that the injection is performed with an isobaric injection rate waveform.
  • the degree of ignition delay is small, it is easy to burn, so heat generation can be made to follow the injection rate.
  • the degree of ignition delay is large, it is difficult to burn, and heat generation does not follow the injection rate. Therefore, even if the injection rate is controlled, heat generation cannot be controlled.
  • the in-cylinder pressure since it is controlled by the isobaric injection rate waveform when it is easy to burn, the in-cylinder pressure can be controlled with high accuracy.
  • the output request to the internal combustion engine is high output, it is necessary to increase the in-cylinder pressure. Therefore, in the case of a high output demand, the in-cylinder pressure is controlled to be close to the maximum in-cylinder pressure while making the in-cylinder pressure below the maximum in-cylinder pressure using the isobaric injection rate waveform.
  • the isobaric injection rate waveform is an injection rate waveform for controlling the in-cylinder pressure in the combustion chamber to be equal to or less than the maximum in-cylinder pressure.
  • the isobaric injection rate waveform is an injection rate waveform in which injection is performed in two stages, upstream injection and downstream injection, and the rate of change in the injection rate increase in upstream injection is greater than the rate of change in downstream injection.
  • the first-half injection with a large rate of change causes the injection rate to rise rapidly to the maximum injection rate, and the in-cylinder pressure is increased to the maximum in-cylinder pressure in a short time. Thereafter, the in-cylinder pressure can be prevented from exceeding the maximum in-cylinder pressure by lowering the injection rate from the maximum injection rate. Furthermore, since the injection rate is greater than 0 at the start of the post-stage injection, it is possible to prevent the in-cylinder pressure from being lowered by excessively lowering the injection rate. In addition, it is possible to prevent the in-cylinder pressure from being increased or decreased excessively by the gradual increase in the rate of change of the injection rate in the subsequent injection. The injection rate is maintained at the maximum injection rate in order to reach a predetermined injection amount, and then the injection rate is lowered from the maximum injection rate.
  • the in-cylinder pressure can be controlled to be close to the maximum in-cylinder pressure below the maximum in-cylinder pressure without exceeding the maximum in-cylinder pressure. Therefore, it is possible to satisfy a high output requirement without increasing the strength of the internal combustion engine.
  • the drawing It is a figure which shows the outline
  • the fuel injection control device is applied to a multi-cylinder diesel engine equipped with a common rail fuel injection device.
  • the engine 10 shown in FIG. 1 is mounted on a vehicle as an in-vehicle main engine, and is a four-cycle engine including intake, compression, expansion, and exhaust strokes.
  • an air flow meter 12 that detects an intake air amount
  • an intercooler 13 that cools intake air supercharged by a turbocharger 16
  • a throttle valve device in order from the upstream side. 14 is provided.
  • the throttle valve device 14 adjusts the opening degree of the throttle valve 14a by an actuator such as a DC motor.
  • a combustion chamber 10 a of each cylinder of the engine 10 is connected to the downstream side of the throttle valve device 14 in the intake passage 11 via a surge tank 15.
  • the combustion chamber 10 a is partitioned by a cylinder 10 b and a piston 17 of the engine 10.
  • the engine 10 is provided with a fuel injection valve 18 having a tip projecting into the combustion chamber 10a.
  • High pressure fuel specifically light oil, is supplied to the fuel injection valve 18 from a common rail 19 serving as a pressure accumulator. Fuel is pumped from the fuel pump 20 to the common rail 19. In FIG. 1, only one cylinder is shown.
  • the fuel injection valve 18 includes a needle 39 that is a valve body, and a body 41 in which a plurality of circular injection holes 40 for injecting fuel are formed at the tip, and the needle 39 is accommodated therein. I have. Between the inner surface of the body 41 and the outer surface of the needle 39, an annular fuel passage 42 extending in the axial direction of the body 41 and through which the fuel supplied from the common rail 19 passes is formed. A seating surface 41 a on which the tip of the needle 39 is seated is formed on the inner surface of the tip of the body 41. In this configuration, when the needle 39 is seated on the seating surface 41a, the fuel passage 42 and the injection hole 40 are blocked, and fuel injection is stopped.
  • the fuel passage 42 and the injection hole 40 are communicated with each other by separating the needle 39 from the seating surface 41a by energization operation.
  • the fuel in the fuel passage 42 is directly injected and supplied from the nozzle hole 40 to the combustion chamber 10a.
  • the fuel injection valve 18 is configured to be able to variably control the injection rate waveform.
  • the injection rate waveform is a waveform showing a change in the injection rate over time.
  • the fuel injection valve 18 is configured to freely control the lift amount of the needle 39 so as to variably control the injection rate waveform.
  • the fuel injection valve 18 is configured such that the injection rate waveform can be changed by speed control of the needle 39 that opens and closes the injection hole 40.
  • the fuel injection valve 18 adjusts the area of the fuel passage 42 by an actuator 43 having a piezo element to inject fuel.
  • the fuel injection valve 18 can change the fuel injection rate waveform.
  • the fuel injection rate in the main injection can be varied over time.
  • the actuator 43 of the fuel injection valve 18 includes, for example, a piezo stack.
  • 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 43 controls the position of the needle 39 using the displacement of the piezo stack.
  • the needle 39 when no voltage is applied to the piezo stack, the needle 39 is in a closed state and fuel injection is not performed.
  • a voltage is applied to the piezo stack, the piezo stack expands, and with the expansion as a motive power, the needle 39 is pushed up and fuel injection is started.
  • the voltage applied to the piezo stack is turned off, it discharges and the piezo stack contracts. As a result, the needle 39 is pushed down to stop fuel injection.
  • the voltage supplied to the actuator 43 By controlling the voltage supplied to the actuator 43, the amount of expansion of the piezo stack can be controlled. Therefore, by controlling the voltage, the valve opening speed of the needle 39 can be adjusted in a plurality of stages, so that the injection seal can be freely controlled.
  • the intake port and the exhaust port of each cylinder of the engine 10 are opened and closed by the intake valve 21 and the exhaust valve 22, respectively.
  • the intake air cooled by the intercooler 13 by opening the intake valve 21 and the external EGR gas are introduced into the combustion chamber 10a.
  • the fuel injection valve 18 into the combustion chamber 10a with intake air or the like introduced the fuel self-ignites due to compression of the combustion chamber 10a, and energy is generated by combustion. This energy is taken out as rotational energy of the crankshaft 23 of the engine 10 via the piston 17.
  • the gas used for combustion is discharged as exhaust into the exhaust passage 24 by opening the exhaust valve 22.
  • a crank angle sensor 25 that detects the rotation angle of the crankshaft 23 is provided in the vicinity of the crankshaft 23.
  • the vehicle is provided with a turbocharger 16.
  • the turbocharger 16 includes an intake air compressor 16a provided in the intake passage 11, an exhaust turbine 16b provided in the exhaust passage 24, and a rotating shaft 16c that connects these. Specifically, the exhaust turbine 16b is rotated by the energy of the exhaust gas flowing through the exhaust passage 24, and the rotational energy is transmitted to the intake compressor 16a via the rotary shaft 16c, and the intake air is compressed by the intake compressor 16a. That is, the intake air is supercharged by the turbocharger 16.
  • the turbocharger 16 can adjust the supercharging pressure of intake air by an energization operation.
  • a purification device 26 for purifying exhaust gas is provided on the downstream side of the turbocharger 16.
  • a part of the exhaust discharged to the exhaust passage 24 is returned to the intake passage 11 via the EGR passage 27.
  • the upstream side of the exhaust turbine 16 b in the exhaust passage 24 is connected to the surge tank 15 via the EGR passage 27.
  • An EGR valve device 28 is provided in the EGR passage 27.
  • the EGR valve device 28 adjusts the opening degree of the EGR valve 28a by an actuator such as a DC motor.
  • a part of the exhaust discharged to the exhaust passage 24 is cooled by the EGR cooler 29 and then supplied to the surge tank 15 as external EGR gas.
  • the ECU30 which is an electronic control apparatus which makes an engine system a control object runs the program memorize
  • the ECU includes at least one arithmetic processing unit (CPU) and a storage medium that stores programs and data.
  • the ECU is realized, for example, by a microcomputer having a storage medium readable by a computer (hereinafter also referred to as “microcomputer”).
  • the storage medium is a non-transitional physical storage medium that stores a computer-readable program and data in a non-temporary manner.
  • the memory is realized by a semiconductor memory or a magnetic disk.
  • the ECU 30 includes an intake pressure sensor 31, an intake temperature sensor 32, an exhaust temperature sensor 33, an in-cylinder pressure sensor 34, an oxygen concentration sensor 38, a fuel pressure sensor 35, a water temperature sensor 36, an accelerator sensor 37, an air flow meter 12, and a crank angle sensor 25.
  • the detected value is input.
  • the intake pressure sensor 31 detects the gas pressure in the surge tank 15 as the intake pressure.
  • the intake air temperature sensor 32 detects the gas temperature in the surge tank 15 as intake sound.
  • the exhaust temperature sensor 33 detects the temperature of the exhaust discharged from the combustion chamber 10a as exhaust sound.
  • the in-cylinder pressure sensor 34 detects the pressure in the combustion chamber 10a as the in-cylinder pressure.
  • the oxygen concentration sensor 38 is attached to the intake passage 11 and detects the oxygen concentration in the intake air.
  • the intake air to be detected is a mixture of fresh air and EGR gas.
  • the fuel pressure sensor 35 detects the fuel pressure in the common rail 19.
  • the water temperature sensor 36 detects the cooling water temperature of the engine 10.
  • the crank angle sensor 25 detects the engine speed that is the rotational speed of the crankshaft 23 that is rotationally driven by the piston 17 and that is the rotational speed of the crankshaft 23 per unit time.
  • the accelerator sensor 37 detects the accelerator operation amount of the accelerator operation member of the driver, and specifically detects the depression amount of the accelerator pedal.
  • the ECU 30 includes a fuel injection control of the fuel injection valve 18, a drive control of the fuel pump 20, a drive control of the EGR valve device 28, and a supercharging pressure control by the turbocharger 16 based on detection values of various sensors. Combustion control is performed. With these controls, the combustion state in the engine 10 included in the combustion system is controlled to a desired state. Therefore, the ECU 30 functions as a control unit that controls the injection rate.
  • the injection mode there are two injection modes, a normal combustion mode and an isobaric combustion mode, and switching control for switching the injection mode under a predetermined condition is performed.
  • the combustion mode is used in the same meaning as the injection rate waveform.
  • the normal injection mode the advance angle is indicated by a broken line, and the advance angle is indicated by a solid line.
  • the injection rate waveform is rectangular as shown in FIG.
  • the maximum in-cylinder pressure may not exceed the maximum in-cylinder pressure before advance.
  • injection control cannot be performed in the normal injection mode after advance.
  • the isobaric combustion mode is an isobaric injection rate waveform, and is an injection rate waveform for controlling the in-cylinder pressure in the combustion chamber 10a to be equal to or lower than the maximum in-cylinder pressure.
  • the in-cylinder pressure is not more than the maximum in-cylinder pressure, and the in-cylinder pressure is maintained for a longer time within a predetermined range that is not more than the maximum in-cylinder pressure.
  • the injection rate waveform is injected into two stages of the front injection and the rear injection, and the rate of change in the injection rate in the front injection is higher than the rate of change in the rear injection. large.
  • the isobaric combustion mode has a front-stage injection that rises quickly to the maximum injection rate and a post-stage injection that rises slowly to the maximum injection rate.
  • the injection rate waveform of the pre-stage injection consists of the part where the injection rate increases from the start of the pre-stage injection and reaches the maximum injection rate, the part that maintains the maximum injection rate for a predetermined time after reaching the maximum injection rate, and the maximum injection rate A descending portion.
  • the injection rate at the start of the subsequent injection is greater than zero.
  • the injection rate waveform of the post-injection includes a portion where the injection rate increases from the start of the post-injection and reaches the maximum injection rate, a portion that maintains the maximum injection rate for a predetermined period after reaching the maximum injection rate, and a maximum injection And a portion descending from the rate.
  • the change in the in-cylinder pressure during the isobaric combustion mode is maintained at the maximum in-cylinder pressure for a predetermined period after reaching the maximum in-cylinder pressure without exceeding the maximum in-cylinder pressure.
  • the constant pressure combustion mode may have a longer period during which the in-cylinder pressure is higher than the normal combustion mode before advancement. Recognize. In the normal combustion mode after advance, the maximum in-cylinder pressure is exceeded and cannot be used in actual injection control. Therefore, in the isobaric combustion mode, the output can be increased more than in the normal combustion mode before and after advance.
  • the switching control shown in FIG. 9 is control that is repeatedly performed when the internal combustion engine is driven.
  • step S11 the operating condition is acquired, and the process proceeds to step S12.
  • the operating conditions are, for example, the engine speed Ne, the accelerator opening ⁇ ac, and the intake pressure Pim.
  • the ECU 30 acquires the accelerator opening degree ⁇ ac from the accelerator sensor 37, acquires the engine speed Ne from the crank angle sensor 25, and acquires the intake pressure Pim that is the in-cylinder pressure from the in-cylinder pressure sensor 34.
  • the intake pressure Pim has a correlation with the degree of ignition delay in the cylinder. Therefore, the ECU 30 functions as an ignition acquisition unit that acquires the degree of ignition delay in the cylinder.
  • the ECU 30 functions as an intake pressure acquisition unit that acquires the intake pressure Pim.
  • step S12 it is determined whether or not there is a high output request from the acquired operating condition. If it is a high output request, the process proceeds to step S13, and if it is not a high output request, the process proceeds to step S16. Whether it is a high output request is determined by whether it is an output request higher than a predetermined output. Whether or not the request is a high output is determined from, for example, the engine speed Ne and the accelerator opening ⁇ ac. When the required injection amount is obtained from the accelerator opening ⁇ ac and the calculated injection amount exceeds the threshold indicated by the broken line in FIG.
  • step S13 it is determined whether or not the intake pressure Pim is greater than or equal to a predetermined intake pressure determination threshold value ⁇ . If the intake pressure determination threshold value ⁇ is greater than or equal to the intake pressure determination threshold value ⁇ , the process proceeds to step S14. Control goes to step S16.
  • the intake pressure determination threshold value ⁇ is determined so that the ignition delay becomes smaller than a predetermined time as shown in FIG. If the ignition delay becomes longer, the maximum in-cylinder pressure Pmax may be exceeded at the time of initial combustion. Therefore, when the intake pressure is such that heat generation follows the injection rate, the process proceeds to step S14.
  • step S14 the target injection pressure and timing are set from the engine speed Ne, the accelerator opening ⁇ ac, and the intake pressure Pim, and the process proceeds to step S15.
  • step S15 since it is a high output request and the intake pressure Pim is equal to or higher than the intake pressure determination threshold value ⁇ , the isobaric injection mode is set, and the process proceeds to step S17.
  • step S16 since it is not a high output request or the intake pressure Pim is not equal to or higher than the intake pressure determination threshold value ⁇ , the normal combustion mode is set, and the process proceeds to step S17.
  • step S17 injection is performed in the set injection mode, and this flow is terminated.
  • the isobaric combustion mode is set. Therefore, the high output requirement can be satisfied by the high output in the isobaric combustion mode.
  • the normal combustion mode is set. Thus, the isobaric combustion mode is performed at a necessary timing, and the normal combustion mode is performed when it is not necessary.
  • variable injection rate is realized by the speed control of the needle 39.
  • speed control is performed on the needle 39 in this manner, cavitation is likely to occur in the nozzle hole 40, and erosion, also called erosion, occurs in the nozzle hole 40 along with the collapse of the cavitation, which may cause excessive injection. Therefore, in order to detect an abnormality in the nozzle hole 40, the monitoring control shown in FIG. 10 is repeatedly performed when the internal combustion engine is driven.
  • step S21 the injection amount at the time of injection according to a predetermined injection instruction is acquired, and the process proceeds to step S22.
  • the injection amount is an injection amount when being injected into the cylinder from the injection hole 40 in a predetermined injection period, injection pressure, and injection rate waveform.
  • the ECU 30 detects the fluctuation amount of the engine speed Ne when the fuel is injected according to a predetermined injection instruction, for example.
  • the ECU 30 calculates engine torque from the fluctuation amount of the engine speed, and calculates the injection amount from the engine torque.
  • ECU30 may acquire the injection quantity from the injection quantity sensor which detects injection quantity, for example. Therefore, the ECU 30 functions as an injection amount acquisition unit that acquires the injection amount.
  • step S22 it is determined whether or not the injection amount has suddenly increased. If the injection amount has suddenly increased, the process proceeds to step S23. If the injection amount has not suddenly increased, this flow is terminated.
  • the case of sudden increase is, for example, a value that exceeds the fluctuation range of the injection amount due to secular change, and the injection amount is increased from the previous injection amount.
  • step S24 assuming that an abnormality has occurred in the nozzle hole 40, control is performed so as to prohibit the isobaric combustion mode, and the process proceeds to step S25.
  • the normal combustion mode is set instead of the isobaric combustion mode even if the process proceeds to step S15 in FIG. If the constant pressure combustion mode is already set, the normal combustion mode is set.
  • step S25 assuming that an abnormality has occurred in the nozzle hole 40, the output is limited and this flow is terminated.
  • the control is performed so that the output is not a high output as required, but a predetermined limit output or less.
  • the monitoring control the increase in the injection amount under the same injection instruction condition is monitored, and when the sudden increase in the injection amount is confirmed, the implementation of the isobaric combustion mode is prohibited and the output is limited. .
  • the fuel injection control device has the constant pressure combustion mode when the intake pressure Pim is equal to or higher than the predetermined intake pressure determination threshold value ⁇ and the output request to the engine 10 is a high output. It is controlled to inject at.
  • the intake pressure Pim is higher than the intake pressure determination threshold value ⁇
  • the degree of ignition delay is small, and heat generation can be made to follow the injection rate.
  • the degree of ignition delay is large and heat generation cannot be made to follow the injection rate, heat generation cannot be controlled with high accuracy even if the injection rate is controlled with high accuracy.
  • the in-cylinder pressure can be controlled with high accuracy by the isobaric combustion mode.
  • the in-cylinder pressure can be made close to the maximum in-cylinder pressure while keeping the in-cylinder pressure below the maximum in-cylinder pressure Pmax.
  • the isobaric combustion mode is an injection rate waveform for controlling the in-cylinder pressure in the combustion chamber 10a to be equal to or less than the maximum in-cylinder pressure Pmax.
  • the isobaric combustion mode is an injection rate waveform in which injection is performed in two stages, upstream injection and downstream injection, and the rate of change in the injection rate increase in upstream injection is greater than the rate of change in downstream injection.
  • the first half injection with a large change rate causes the injection rate to rapidly increase to the maximum injection rate, and the in-cylinder pressure is increased to the maximum in-cylinder pressure Pmax in a short time. Thereafter, the in-cylinder pressure can be prevented from exceeding the maximum in-cylinder pressure Pmax by lowering the injection rate from the maximum injection rate. Furthermore, since the injection rate is greater than 0 at the start of the post-stage injection, it is possible to prevent the in-cylinder pressure from being lowered by excessively lowering the injection rate. In addition, it is possible to prevent the in-cylinder pressure from being increased or decreased excessively by the gradual increase in the rate of change of the injection rate in the subsequent injection. The injection rate is maintained at the maximum injection rate in order to reach a predetermined injection amount, and then the injection rate is lowered from the maximum injection rate.
  • the in-cylinder pressure can be controlled to be close to the maximum in-cylinder pressure Pmax that is equal to or less than the maximum in-cylinder pressure Pmax without exceeding the maximum in-cylinder pressure Pmax. This ensures maximum work. Therefore, the high output requirement can be satisfied without increasing the strength of the engine 10.
  • the isobaric combustion mode is effective in order to maximize the output performance in the engine 10 in which the maximum in-cylinder pressure Pmax is determined.
  • the injection rate waveform is set so that the target in-cylinder pressure profile preset in the engine 10 matches the actual in-cylinder pressure profile.
  • the target in-cylinder pressure profile is a profile that can maintain the maximum in-cylinder pressure at the maximum in-cylinder pressure Pmax and has a large output.
  • the injection rate waveform is determined so as to obtain such a target in-cylinder pressure profile.
  • pre-stage injection and post-stage injection are performed, but the injection rate is greater than 0 at the start of the post-stage injection.
  • the injection rate at the start of the subsequent stage is larger than 0 as in the present embodiment, the influence of the throttle generated when the valve is closed can be reduced to prevent the smoke from getting worse.
  • the injection rate at the time of subsequent disclosure is preferably such that the flow area of the throttle generated when the needle 39 is opened is larger than the flow area of the nozzle hole 40.
  • the injection in the isobaric combustion mode is prohibited, and the injection is controlled in the normal combustion mode that is another injection rate waveform. Yes. Accordingly, when the injection amount changes suddenly and an abnormality occurs in the nozzle hole 40, it is possible to prevent the isobaric combustion mode from being performed. When an abnormality occurs in the nozzle hole 40, when the isobaric combustion mode is performed, the time during which the maximum in-cylinder pressure is reached is long, so that the influence on the injection amount due to the abnormality in the nozzle hole 40 may be increased.
  • the normal combustion mode in which the in-cylinder pressure is lower than the isobaric combustion mode it is possible to suppress the influence caused by the abnormality of the nozzle hole 40. Further, when an abnormality occurs in the nozzle hole 40, the user may be notified that the abnormality has occurred.
  • the intake pressure Pim when the intake pressure Pim is equal to or higher than the intake pressure determination threshold value ⁇ and the output request to the engine 10 is a high output, control is performed so that the injection is performed in the isobaric combustion mode.
  • the intake pressure Pim is equal to or higher than the intake pressure determination threshold value ⁇
  • the ignition delay is small and combustion is easy.
  • heat generation can follow the injection rate waveform.
  • the isobaric combustion mode when the isobaric combustion mode is performed, the actual in-cylinder pressure profile can be brought close to the target in-cylinder pressure profile.
  • FIG. 13 a second embodiment will be described using FIG. 13 and FIG.
  • the present embodiment is characterized in that not the intake pressure Pim but the oxygen concentration O2im is used to determine the inflammability in the cylinder.
  • the injection mode switching control of this embodiment will be described.
  • the switching control shown in FIG. 13 is control that is repeatedly performed when the internal combustion engine is driven.
  • step S31 as in step S11, the operating conditions are acquired, and the process proceeds to step S32.
  • the operating conditions include the oxygen concentration O2im. Therefore, the ECU 30 functions as an oxygen concentration acquisition unit that acquires the oxygen concentration of the intake air.
  • step S32 similarly to step S12, it is determined whether or not a high output request is made based on the obtained operating condition. If the request is a high output request, the process proceeds to step S33, and if not, the process proceeds to step S36. .
  • step S33 it is determined whether or not the oxygen concentration O2im is equal to or greater than a predetermined oxygen concentration determination threshold ⁇ . If the oxygen concentration determination threshold ⁇ is equal to or greater than step S34, the process proceeds to step S34. Control goes to step S36.
  • the oxygen concentration determination threshold value ⁇ is determined so that the ignition delay becomes smaller than a predetermined time as shown in FIG.
  • step S34 similarly to step S14, the target injection pressure and timing are set from the engine speed Ne, the accelerator opening ⁇ ac, and the intake pressure Pim, and the process proceeds to step S35.
  • step S35 since it is a high output request and the oxygen concentration O2im is equal to or higher than the oxygen concentration determination threshold value ⁇ , the isobaric injection mode is set, and the process proceeds to step S37.
  • step S36 it is not a high output request or the oxygen concentration O2im is not equal to or higher than the oxygen concentration determination threshold value ⁇ , so the normal combustion mode is set, and the process proceeds to step S37.
  • step S37 as in step S17, injection is performed in the set injection mode, and this flow ends.
  • the isobaric combustion mode in the case of a high output demand, a condition where the oxygen concentration is high, the ignition delay is small, and combustion is easy, the isobaric combustion mode is set.
  • the high output requirement can be satisfied by the high output in the isobaric combustion mode.
  • the normal combustion mode is set.
  • the isobaric combustion mode is performed at a necessary timing, and the normal combustion mode is performed when it is not necessary.
  • the oxygen concentration of the intake air is acquired by the oxygen concentration sensor 38, but is not limited to the oxygen concentration sensor 38, and the oxygen concentration is estimated from a correlated numerical value, for example, an EGR rate. Also good.
  • the oxygen concentration O2im is used to determine the ignition delay, but without determining only the oxygen concentration O2im, the degree of ignition delay is acquired by both the intake pressure Pim and the oxygen concentration O2im, You may judge the flammability. This makes it possible to determine the easiness of burning with higher accuracy.
  • injection rate waveforms are switched.
  • the present invention is not limited to two injection rate waveforms, and three or more injection rate waveforms may be switched.
  • the control is not limited to switching between the isobaric combustion mode and the normal combustion mode, but may be control switching between the isobaric combustion mode and another injection mode.
  • Other injection modes include, for example, an injection rate waveform having a boot shape, a ⁇ shape, a trapezoidal shape, and a staircase shape.
  • the actuator 43 of the fuel injection valve 18 uses a piezoelectric element, but is not limited to such a configuration. Any configuration capable of adjusting the valve opening speed may be used. 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 adjusted by switching these chambers.
  • the combustion is likely to occur when the degree of the ignition delay is smaller than the threshold value.
  • the intake pressure Pim and the oxygen concentration O2im it is not limited to the intake pressure Pim and the oxygen concentration O2im.
  • the EGR rate may be used, or may be determined using other values.
  • the functions realized by the ECU 30 may be realized by hardware and software different from those described above, or a combination thereof.
  • the ECU 30 may realize each functional block such as a control unit that performs injection control by one processor.
  • the ECU 30 may communicate with, for example, another control device, and the other control device may execute part or all of the processing.
  • the ECU 30 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.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
PCT/JP2016/086198 2015-12-10 2016-12-06 燃料噴射制御装置 WO2017099064A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10259753A (ja) * 1997-03-18 1998-09-29 Denso Corp 燃料噴射制御方法及び燃料噴射制御装置
JP2009085117A (ja) * 2007-10-01 2009-04-23 Mazda Motor Corp ディーゼルエンジンの制御装置
JP2013209943A (ja) * 2012-03-30 2013-10-10 Toyota Motor Corp エンジンの燃料性状推定装置
JP2014227905A (ja) * 2013-05-22 2014-12-08 トヨタ自動車株式会社 内燃機関の熱発生率波形作成装置および燃焼状態診断装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69739267D1 (de) 1997-12-31 2009-04-02 St Microelectronics Srl Methode und Schaltung zur Verbesserung der Eigenschaften eines ESD-Schutzes für integrierte Halbleiterschaltungen
JP2011153579A (ja) 2010-01-27 2011-08-11 Mitsubishi Heavy Ind Ltd ディーゼルエンジンの制御装置
JP6447434B2 (ja) 2015-09-15 2019-01-09 株式会社デンソー 燃料噴射制御装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10259753A (ja) * 1997-03-18 1998-09-29 Denso Corp 燃料噴射制御方法及び燃料噴射制御装置
JP2009085117A (ja) * 2007-10-01 2009-04-23 Mazda Motor Corp ディーゼルエンジンの制御装置
JP2013209943A (ja) * 2012-03-30 2013-10-10 Toyota Motor Corp エンジンの燃料性状推定装置
JP2014227905A (ja) * 2013-05-22 2014-12-08 トヨタ自動車株式会社 内燃機関の熱発生率波形作成装置および燃焼状態診断装置

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DE112016005640B4 (de) 2022-08-25

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