WO2012108005A1 - セタン価推定装置 - Google Patents
セタン価推定装置 Download PDFInfo
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- WO2012108005A1 WO2012108005A1 PCT/JP2011/052656 JP2011052656W WO2012108005A1 WO 2012108005 A1 WO2012108005 A1 WO 2012108005A1 JP 2011052656 W JP2011052656 W JP 2011052656W WO 2012108005 A1 WO2012108005 A1 WO 2012108005A1
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- fuel
- cetane number
- fuel injection
- amount
- injection
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- 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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/04—Introducing corrections for particular operating conditions
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- 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
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
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- 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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1497—With detection of the mechanical response of the engine
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- 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
- F02D2200/021—Engine temperature
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- 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
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- 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
- F02D2200/06—Fuel or fuel supply system parameters
- F02D2200/0606—Fuel temperature
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- 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
- F02D2200/06—Fuel or fuel supply system parameters
- F02D2200/0611—Fuel type, fuel composition or fuel quality
- F02D2200/0612—Fuel type, fuel composition or fuel quality determined by estimation
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- 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
- F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
- F02D2200/101—Engine speed
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- 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
- F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
- F02D2200/1012—Engine speed gradient
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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
- F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
- F02M2200/95—Fuel injection apparatus operating on particular fuels, e.g. biodiesel, ethanol, mixed fuels
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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
- F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
- F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
- F02M47/027—Electrically actuated valves draining the chamber to release the closing pressure
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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
- F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
- F02M63/0012—Valves
- F02M63/0014—Valves characterised by the valve actuating means
- F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
- F02M63/0026—Valves characterised by the valve actuating means electrical, e.g. using solenoid using piezoelectric or magnetostrictive actuators
Definitions
- the present invention relates to a cetane number estimation device for estimating the cetane number of fuel supplied to a diesel engine.
- the fuel injected into the combustion chamber by the fuel injection valve is compressed and ignited after a predetermined time (so-called ignition delay) has elapsed since the injection.
- ignition delay a predetermined time
- a control device that controls the execution mode of engine control such as injection timing and injection amount for fuel injection is widely adopted in consideration of such ignition delay. Yes.
- Patent Document 1 proposes an apparatus that injects a small amount of fuel from a fuel injection valve and estimates the cetane number of the fuel based on the engine torque generated by the fuel injection.
- the relationship between the fuel injection amount and the output torque of the diesel engine changes according to the cetane number of the fuel.
- the cetane number of the fuel is estimated based on the relationship.
- Fuel light oil
- hydrocarbons hydrocarbons having various structures.
- various substances are added to the fuel in order to obtain certain characteristics. For this reason, it is considered that the hydrocarbon density in the fuel varies depending on the fuel production time and production location, and the generated heat quantity varies due to the density variation.
- An object of the present invention is to provide a cetane number estimation device capable of accurately estimating the cetane number of fuel.
- the present invention provides a cetane number estimation device that performs fuel injection at a predetermined injection amount in order to estimate the cetane number of fuel to be used for combustion of a diesel engine, An index value of the generated heat amount accompanying combustion of the engine is detected, an index value of the output torque of the diesel engine generated by the execution of fuel injection at the predetermined injection amount is calculated, and the cetane number is calculated based on these index values presume.
- the cetane number of the fuel is estimated in consideration of the effect of the change. Will be able to. Accordingly, the estimation error of the cetane number of the fuel due to the variation in the heat generation amount of the fuel can be suppressed to be small, and the cetane number of the fuel can be estimated with high accuracy.
- the apparatus stores in advance a relationship between an estimated value of cetane number and an index value of output torque, and corrects the relationship based on an index value of the amount of generated heat.
- An estimated value of the cetane number is calculated based on the relationship and the index value of the output torque.
- the device stores in advance a relationship between an estimated value of cetane number and an index value of output torque, corrects the index value of output torque based on the index value of generated heat, Based on the corrected index value and the relationship, an estimated value of the cetane number is calculated.
- the device performs fuel injection for estimating the cetane number based on the injection amount corrected according to the index value of the generated heat amount, and outputs torque calculated with the execution of the fuel injection. Estimate the cetane number based on the index value.
- the apparatus calculates the index value of the output torque of the diesel engine generated along with the execution of the fuel injection while performing the fuel injection at a predetermined injection amount so as to detect the heat generated by the fuel,
- the calculated index value is used as an index value for the amount of generated heat.
- the device further performs fuel injection for detecting the amount of generated heat based on the target injection amount, and further includes a pressure sensor that detects a fuel pressure that is an index of fuel pressure inside the fuel injection valve, The target injection amount is corrected based on the fluctuation waveform of the fuel pressure detected by the pressure sensor during fuel injection.
- the apparatus calculates an actual operating characteristic of the fuel injection valve based on the detected fluctuation waveform of the fuel pressure, and calculates a target injection amount based on a difference between the calculated actual operating characteristic and a predetermined basic operating characteristic. It is preferable to correct.
- the device detects the temperature of the fuel with a temperature sensor and corrects the target injection amount based on the detected fuel temperature. In a preferred aspect, the device performs the detection of the fuel temperature by the temperature sensor immediately before the start of the fuel injection for detecting the amount of generated heat.
- the apparatus performs fuel injection for estimating a cetane number based on a target fuel injection amount, and detects a fuel pressure that is an index of fuel pressure inside the fuel injection valve.
- a sensor is further provided, and the target fuel injection amount is corrected based on the fluctuation waveform of the fuel pressure detected by the pressure sensor during fuel injection.
- the apparatus calculates an actual operating characteristic of the fuel injection valve based on the detected fluctuation waveform of the fuel pressure, and based on a difference between the calculated actual operating characteristic and a predetermined basic operating characteristic. To correct the target fuel injection amount.
- the device performs fuel injection for estimating the cetane number based on a target fuel injection amount, detects the temperature of the fuel with a temperature sensor, and detects the detected fuel temperature. Based on this, the target fuel injection amount is corrected.
- the apparatus performs the detection of the fuel temperature by the temperature sensor immediately before the start of the fuel injection for estimating the cetane number.
- the pressure sensor is preferably attached to the fuel injection valve.
- the graph which shows the relationship between a rotation fluctuation amount, a rotational speed at the time of execution, and the cetane number of fuel The graph which shows the relationship between a rotation fluctuation amount, a rotational speed at the time of execution, and the execution time of fuel injection.
- the flowchart which shows the execution procedure of a detection control process Explanatory drawing explaining the calculation method of rotation fluctuation amount.
- a cetane number estimating device As shown in FIG. 1, a vehicle 1 is equipped with a diesel engine 10 as a drive source.
- the crankshaft 14 of the diesel engine 10 is connected to the wheels 4 via the clutch mechanism 2 and the manual transmission 3.
- a clutch operating member for example, a clutch pedal
- the clutch mechanism 2 enters an operating state in which the connection between the crankshaft 14 and the manual transmission 3 is released.
- An intake passage 12 is connected to the cylinder 11 of the diesel engine 10. Air is sucked into the cylinder 11 of the diesel engine 10 through the intake passage 12. Further, as the diesel engine 10, an engine having a plurality of (four [# 1 to # 4] in the present embodiment) cylinders 11 is employed. A direct injection type fuel injection valve 20 that directly injects fuel into the cylinder 11 is attached to the diesel engine 10 for each cylinder 11. The fuel injected by opening the fuel injection valve 20 is ignited and burned in contact with the intake air compressed and heated in the cylinder 11 of the diesel engine 10. In the diesel engine 10, the piston 13 is pushed down by the energy generated by the combustion of the fuel in the cylinder 11, and the crankshaft 14 is forcibly rotated. The combustion gas combusted in the cylinder 11 of the diesel engine 10 is discharged as exhaust gas into the exhaust passage 15 of the diesel engine 10.
- the diesel engine 10 is provided with an exhaust-driven supercharger 16.
- the supercharger 16 includes a compressor 17 attached to the intake passage 12 of the diesel engine 10 and a turbine 18 attached to the exhaust passage 15.
- the supercharger 16 pumps intake air that passes through the intake passage 12 by using the energy of the exhaust that passes through the exhaust passage 15 of the diesel engine 10.
- Each fuel injection valve 20 is individually connected to a common rail 34 via a branch passage 31a, and the common rail 34 is connected to a fuel tank 32 via a supply passage 31b.
- a fuel pump 33 that pumps fuel is provided in the supply passage 31b.
- the fuel boosted by the pumping by the fuel pump 33 is stored in the common rail 34 and supplied to each fuel injection valve 20.
- a return passage 35 is connected to each fuel injection valve 20, and each return passage 35 is connected to a fuel tank 32. Part of the fuel inside the fuel injection valve 20 is returned to the fuel tank 32 through the return passage 35.
- a needle valve 22 is provided inside the housing 21 of the fuel injection valve 20.
- the needle valve 22 is provided in a state capable of reciprocating in the housing 21 (moving up and down in the figure).
- a spring 24 that constantly urges the needle valve 22 toward the injection hole 23 (the lower side in the figure).
- a nozzle chamber 25 is formed in the housing 21 at a position on one side (lower side in the figure) with the needle valve 22 interposed therebetween, and on the other side (upper side in the figure).
- a pressure chamber 26 is formed.
- the nozzle chamber 25 has an injection hole 23 that communicates the inside with the outside of the housing 21, and fuel is supplied from the branch passage 31 a (common rail 34) through the introduction passage 27.
- the pressure chamber 26 is connected to the nozzle chamber 25 and the branch passage 31a (common rail 34) via a communication passage 28.
- the pressure chamber 26 is connected to a return passage 35 (fuel tank 32) via a discharge passage 30.
- a piezoelectric actuator 29 in which a piezoelectric element (for example, a piezo element) that expands and contracts by input of a drive signal is provided in the housing 21.
- a valve body 29 a is attached to the piezoelectric actuator 29, and the valve body 29 a is provided inside the pressure chamber 26. Then, through the movement of the valve element 29 a by the operation of the piezoelectric actuator 29, one of the communication path 28 (nozzle chamber 25) and the discharge path 30 (return path 35) is selectively communicated with the pressure chamber 26. It has become.
- the piezoelectric actuator 29 expands to move the valve element 29a, the communication between the communication passage 28 and the pressure chamber 26 is cut off, and the return passage. 35 and the pressure chamber 26 are in communication with each other.
- part of the fuel in the pressure chamber 26 is returned to the fuel tank 32 via the return passage 35 in a state where fuel outflow from the nozzle chamber 25 to the pressure chamber 26 is prohibited.
- the pressure of the fuel in the pressure chamber 26 decreases and the pressure difference between the pressure chamber 26 and the nozzle chamber 25 increases, and the pressure difference causes the needle valve 22 to move against the biasing force of the spring 24 and inject.
- the fuel injection valve 20 is in a state in which fuel is injected (opened state) at this time.
- a fuel sensor 41 that outputs a signal corresponding to the fuel pressure PQ inside the introduction passage 27 is integrally attached to the fuel injection valve 20. For this reason, for example, the fuel in a portion near the injection hole 23 of the fuel injection valve 20 as compared with a device that detects the fuel pressure at a position away from the fuel injection valve 20 such as the fuel pressure in the common rail 34 (see FIG. 1). The pressure can be detected, and the change in the fuel pressure inside the fuel injection valve 20 accompanying the opening of the fuel injection valve 20 can be detected with high accuracy.
- the fuel sensor 41 one that functions as a pressure sensor and also functions as a temperature sensor for detecting the fuel temperature (THQ) inside the introduction passage 27 is employed. Switching of the function of the fuel sensor 41 is performed by signal input from an electronic control unit 40 described later. Further, one fuel sensor 41 is provided for each fuel injection valve 20, that is, for each cylinder 11 of the diesel engine 10.
- the diesel engine 10 is provided with various sensors as peripheral devices for detecting the operating state.
- sensors in addition to the fuel sensor 41, for example, a supercharging pressure sensor 42 for detecting the pressure (supercharging pressure PA) in the intake passage 12 downstream of the compressor 17 in the intake flow direction, A crank sensor 43 for detecting the rotational phase (crank angle CA) and rotational speed (engine rotational speed NE) of the shaft 14 is provided.
- a water temperature sensor 44 for detecting the temperature (THW) of the cooling water of the diesel engine 10
- a storage amount sensor 45 for detecting the amount of fuel stored in the fuel tank 32
- an accelerator operating member for example, an accelerator pedal
- an accelerator operation amount sensor 46 for detecting the operation amount (accelerator operation amount ACC).
- a vehicle speed sensor 47 for detecting the traveling speed of the vehicle 1 and a clutch switch 48 for detecting whether or not the clutch operating member is operated are also provided.
- an electronic control unit 40 configured with a microcomputer.
- the electronic control unit 40 that functions as an estimation unit that estimates the cetane number of the fuel takes in the output signals of various sensors and performs various calculations based on the output signals, and the fuel injection valve 20 according to the calculation results.
- Various controls related to the operation of the diesel engine 10 such as operation control (fuel injection control) are executed.
- the fuel injection control of the present embodiment is basically executed as follows. First, a control target value (required injection amount TAU) for the fuel injection amount for engine operation based on the accelerator operation amount ACC, the engine rotational speed NE, the cetane number of the fuel (specifically, an estimated cetane number described later), and the like. Is calculated. Thereafter, a control target value for fuel injection timing (required injection timing Tst) and a control target value for fuel injection time (required injection time Ttm) are calculated based on the required injection amount TAU and the engine speed NE. Based on the required injection timing Tst and the required injection time Ttm, the valve opening drive of each fuel injection valve 20 is executed. Thus, an amount of fuel commensurate with the operation state of the diesel engine 10 at that time is injected from each fuel injection valve 20 and supplied into each cylinder 11 of the diesel engine 10.
- the operation control (rail pressure control) of the fuel pump 33 is executed in conjunction with the execution of the fuel injection control.
- This rail pressure control is executed to adjust the fuel pressure (rail pressure) in the common rail 34 in a manner corresponding to the operating state of the diesel engine 10.
- a control target value (required rail pressure Tpr) for the rail pressure is calculated based on the required injection amount TAU and the engine rotational speed NE. Then, the operation of the fuel pump 33 is controlled so that the required rail pressure Tpr matches the actual rail pressure, and the fuel pumping amount is adjusted.
- a detection time waveform of the fuel injection rate is generated based on the fuel pressure PQ detected by the fuel sensor 41.
- a correction process for correcting the required injection timing Tst and the required injection time Ttm based on the detected time waveform is performed. This correction process is executed separately for each cylinder 11 of the diesel engine 10.
- Such correction processing will be described in detail.
- the fuel pressure inside the fuel injection valve 20 is reduced when the fuel injection valve 20 is opened, and then increased when the fuel injection valve 20 is closed. It fluctuates with it. Therefore, the actual operating characteristics of the fuel injection valve 20 (for example, the timing when the valve opening operation is started or the timing when the valve closing operation is started) are monitored by monitoring the fluctuation waveform of the fuel pressure when the fuel injection is performed. It can be accurately grasped.
- FIG. 3 shows the relationship between the transition of the fuel pressure PQ and the detection time waveform of the fuel injection rate.
- valve opening operation start timing Tos the timing at which the fuel injection valve 20 opens (specifically, the movement of the needle valve 22 toward the valve opening side) starts (valve opening operation start timing Tos), When the fuel injection rate becomes maximum (maximum injection rate arrival time Toe), when the fuel injection rate starts to decrease (injection rate decrease start time Tcs), and when the fuel injection valve 20 closes (specifically, the needle valve 22) ) (The movement to the valve closing side) is completed (valve closing operation completion timing Tce).
- the average value of the fuel pressure PQ in the predetermined period T1 immediately before the start of the valve opening operation of the fuel injection valve 20 is calculated, and the average value is stored as the reference pressure Pbs.
- the reference pressure Pbs is used as a pressure corresponding to the fuel pressure inside the fuel injection valve 20 when the valve is closed.
- the predetermined pressure P1 corresponds to the change in the fuel pressure PQ, that is, the movement of the needle valve 22 even when the needle valve 22 is in the closed position when the fuel injection valve 20 is driven to open or close. This is a pressure corresponding to a change in the fuel pressure PQ that does not contribute.
- a first-order differential value of the fuel pressure PQ during a period in which the fuel pressure PQ drops immediately after the start of fuel injection is calculated.
- a tangent line L1 of the time waveform of the fuel pressure PQ at the point where the first-order differential value is minimized is obtained, and an intersection point A between the tangent line L1 and the operating pressure Pac is calculated.
- the timing corresponding to the point AA where the intersection A is returned to the past timing by the detection delay of the fuel pressure PQ is specified as the valve opening operation start timing Tos.
- the detection delay is a period corresponding to the delay of the change timing of the fuel pressure PQ with respect to the pressure change timing of the nozzle chamber 25 (see FIG. 2) of the fuel injection valve 20, and the distance between the nozzle chamber 25 and the fuel sensor 41. This is a delay caused by the above.
- the first-order differential value of the fuel pressure PQ during the period in which the fuel pressure PQ rises after dropping once immediately after the start of fuel injection is calculated.
- the tangent L2 of the time waveform of the fuel pressure PQ at the point where the first-order differential value becomes maximum is obtained, and the intersection B between the tangent L2 and the operating pressure Pac is calculated.
- the timing corresponding to the point BB where the intersection B is returned to the past timing by the detection delay is specified as the valve closing operation completion timing Tce.
- a time CC at which the intersection C is returned to the past time by the detection delay is calculated, and a point D at which the virtual maximum fuel injection rate VRt is reached at the same time CC is specified.
- the timing corresponding to the intersection E between the straight line L3 connecting the point D and the valve opening operation start timing Tos (specifically, the point at which the fuel injection rate becomes “0” at the same time Tos) and the maximum injection rate Rt is obtained. It is specified as the maximum injection rate arrival time Toe.
- the timing corresponding to the intersection F between the straight line L4 and the maximum injection rate Rt connecting the point D and the valve closing operation completion timing Tce (specifically, the point at which the fuel injection rate becomes “0” at the same time Tce) is injected. It is specified as the rate drop start time Tcs.
- the trapezoidal time waveform formed by the valve opening operation start timing Tos, the maximum injection rate arrival timing Toe, the injection rate drop start timing Tcs, the valve closing operation completion timing Tce and the maximum injection rate Rt is a fuel injection rate in fuel injection. Is used as a detection time waveform.
- FIG. 4 is a flowchart showing a specific procedure of the correction process, and the series of processes shown in the flowchart is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.
- 5 and 6 show examples of the relationship between the detection time waveform and the basic time waveform, respectively.
- a detection time waveform in fuel injection is formed based on the fuel pressure PQ (step S101). Further, a basic value (basic time waveform) for the time waveform of the fuel injection rate in the fuel injection is set based on the operation state of the diesel engine 10 such as the accelerator operation amount ACC and the engine speed NE (step S102). In the present embodiment, the relationship between the operation state of the diesel engine 10 and the basic time waveform suitable for the operation state is obtained in advance based on the results of experiments and simulations and stored in the electronic control unit 40. In the process of step S102, a basic time waveform is set from the above relationship based on the operation state of the diesel engine 10 at that time. In the present embodiment, the detection time waveform functions as an actual operation characteristic of the fuel injection valve 20, and the basic time waveform functions as a predetermined basic operation characteristic.
- the basic time waveform (one-dot chain line) includes the valve opening operation start timing Tosb, the maximum injection rate arrival timing Toeb, the injection rate drop start timing Tcsb, the valve closing operation completion timing Tceb, and the maximum injection rate.
- the specified trapezoidal time waveform is set.
- a difference ⁇ Tos between the valve opening operation start timing Tosb in the basic time waveform and the valve opening operation start timing Tos in the detection time waveform is calculated (step S103 in FIG. 4), and the difference ⁇ Tos and the required injection amount are calculated.
- a correction term K1 is calculated and stored based on the TAU and the engine speed NE (step S104).
- the relationship between the situation determined by the difference ⁇ Tos, the required injection amount TAU and the engine rotational speed NE and the correction term K1 that can accurately compensate for the difference ⁇ Tos is based on the results of experiments and simulations. It is obtained and stored in the electronic control unit 40.
- the correction term K1 is calculated based on this relationship.
- a difference ⁇ Tcs between the injection rate decrease start timing Tcsb (FIG. 5) in the basic time waveform and the injection rate decrease start timing Tcs in the detection time waveform is calculated (step S105 in FIG. 4), and the difference ⁇ Tcs and the requested injection are calculated.
- a correction term K2 is calculated and stored based on the amount TAU and the engine speed NE (step S106).
- the relationship between the situation determined by the difference ⁇ Tcs, the required injection amount TAU and the engine speed NE and the correction term K2 capable of accurately compensating the difference ⁇ Tcs is based on the results of experiments and simulations. It is obtained and stored in the electronic control unit 40. In the process of step S106, the correction term K2 is calculated based on this relationship.
- the difference in the change rate of the fuel injection rate between the basic time waveform (one-dot chain line) and the detection time waveform (solid line) is calculated (step S107). .
- the difference ⁇ Rup in the slope of the line connecting the valve opening operation start time Tos (or Tosb) and the maximum injection rate arrival time Toe (or Toeb) is calculated as the difference in the rate of increase in the fuel injection rate.
- the difference ⁇ Rdn in the slope of the line connecting the injection rate decrease start timing Tcs (or Tcsb) and the valve closing operation completion timing Tce (or Tcsb) is calculated as the difference in the fuel injection rate decrease rate.
- the differences ⁇ Rup and ⁇ Rdn are calculated as values having a high correlation with the area difference between the basic time waveform and the detection time waveform. Then, the correction term K3 is calculated and stored based on the differences ⁇ Rup, ⁇ Rdn, the required injection amount TAU, and the engine speed NE (step S108).
- the situation determined by the differences ⁇ Rup, ⁇ Rdn, the required injection amount TAU, and the engine speed NE, the area of the basic time waveform and the detection time waveform (specifically, the fuel injection rate and the fuel injection rate in the waveform are
- the relationship with the correction term K3 that can accurately compensate for the difference in the area surrounded by the line “0” is obtained in advance based on the results of experiments and simulations, and stored in the electronic control unit 40. Yes.
- the correction term K3 is calculated based on this relationship.
- a value obtained by correcting the required injection timing Tst by the correction term K1 (in this embodiment, a value obtained by adding the correction term K1 to the required injection timing Tst) is calculated as the final required injection timing Tst. Is done.
- a value obtained by correcting the required injection time Ttm by the correction terms K2 and K3 (in this embodiment, a value obtained by adding the correction terms K2 and K3 to the required injection time Ttm) is calculated as the final required injection time Ttm.
- the required injection timing Tst and the request are based on the difference between the actual operating characteristics (specifically, the detection time waveform) of the fuel injection valve 20 and the predetermined basic operating characteristics (specifically, the basic time waveform). Since the injection time Ttm is corrected, a deviation between the actual operating characteristics of the fuel injector 20 and the basic operating characteristics (the operating characteristics of the fuel injector having standard characteristics) can be suppressed. In this way, the fuel injection execution time and execution time are appropriately set so as to match the operating state of the diesel engine 10.
- the valve opening operation start timing and the injection rate fall start timing both coincide between the basic time waveform and the detection time waveform, the rate of increase of the fuel injection rate between the basic time waveform and the detection time waveform
- the area of the basic time waveform and the area of the detection time waveform do not coincide with each other, and the fuel injection amount may deviate from the amount corresponding to the operation state of the diesel engine 10.
- the correction by the correction term K3 since the area difference between the basic time waveform and the detection time waveform is suppressed by the correction by the correction term K3, the fuel injection amount in the fuel injection is brought into the operating state of the diesel engine 10. It will be accurately adjusted to the appropriate amount.
- the rail pressure control since the rail pressure control is executed, the amount of change in the valve opening operation start timing when the required injection timing Tst is changed by the same value, or the required injection by the same value.
- the time Ttm When the time Ttm is changed, the amount of change in the injection rate drop start timing varies depending on the rail pressure.
- the rail pressure (specifically, the required injection amount TAU and the engine rotational speed NE, which are calculation parameters for the required rail pressure Tpr) is employed as the calculation parameters used for calculating the correction terms K1, K2, and K3. is doing. Therefore, the correction terms K1, K2, and K3 are appropriately calculated according to the rail pressure at that time.
- control for estimating the cetane number of the fuel is executed.
- This estimation control is basically executed as follows. That is, first, when the execution condition is satisfied, fuel injection is performed in a predetermined amount (for example, several cubic millimeters), and an index of the output torque of the diesel engine 10 generated in accordance with the execution of the fuel injection. A value (rotational fluctuation amount ⁇ NE described later) is calculated. Then, the cetane number of the fuel is estimated based on this rotational fluctuation amount ⁇ NE. The higher the cetane number of the fuel supplied to the diesel engine 10, the easier the fuel is ignited, and the less unburned fuel of the fuel decreases, so the engine torque generated with the combustion of the fuel increases. In the estimation control of the present embodiment, the cetane number of the fuel is estimated based on the relationship between the cetane number of the fuel and the output torque of the diesel engine 10.
- the output torque of the diesel engine 10 generated when a predetermined amount of fuel is injected changes in accordance with the engine rotational speed NE in addition to changing in accordance with the cetane number of the fuel. This is due to the following reasons.
- FIG. 7 shows an example of the relationship between the temperature (or pressure) in the combustion chamber 11a of the diesel engine 10 and the engine rotational speed NE.
- the engine speed NE when the engine speed NE is increased, the time during which the combustion chamber 11a is in a high temperature and high pressure state is shortened. Therefore, when fuel injection with a predetermined amount is executed in the above estimation control, the higher the engine speed NE, the lower the temperature and pressure in the combustion chamber 11a, and the more likely it is that fuel remains unburned. Therefore, the output torque of the diesel engine 10 generated with the fuel injection tends to be small.
- FIG. 8 shows the relationship between the rotational fluctuation amount ⁇ NE, the engine speed NE, and the cetane number of the fuel when fuel injection is executed under the same injection timing and injection amount.
- the execution speed when fuel injection is executed under the same injection timing and injection amount, when the engine speed NE (hereinafter referred to as the execution speed) at the time of execution is high.
- the output torque of the diesel engine 10 (specifically, the rotational fluctuation amount ⁇ NE that is the index value) becomes smaller.
- the output torque of the diesel engine 10 generated when a predetermined amount of fuel is injected changes in accordance with the cetane number of the fuel and the engine rotational speed NE, and also changes depending on the execution timing of the fuel injection. .
- FIG. 9 shows the relationship between the rotational fluctuation amount ⁇ NE, the rotational speed at the time of execution, and the execution timing of the fuel injection when fuel injection is executed under the same conditions of the cetane number and the injection amount of the fuel.
- the output torque of the diesel engine 10 generated with fuel injection (specifically, the rotational fluctuation amount ⁇ NE, which is an index value), as the execution timing of fuel injection is delayed. Becomes smaller. This is because as the fuel injection execution timing is delayed, the fuel burns in a state where the temperature and pressure in the combustion chamber 11a are low, and the amount of unburned fuel increases. Conceivable.
- the cetane number of the fuel is estimated based on the relationship between the rotational fluctuation amount ⁇ NE and the execution timing of fuel injection by the estimation control and the rotational speed at the time of execution.
- the region where the output torque is at the upper limit includes a region where the fuel injection is performed in a state where the engine speed NE is low (see FIG. 8), and a region where the fuel injection is performed at the advance timing (FIG. 9). Reference).
- the output torque of the diesel engine 10 becomes the upper limit without depending on the cetane number of the fuel. Therefore, the cetane number of the fuel is determined based on the output torque (specifically, the rotational fluctuation amount ⁇ NE). I can't.
- the region where the output torque becomes the lower limit is a region where the fuel injection is performed in a situation where the engine rotational speed NE is high (see FIG. 8), or a region where the fuel injection is performed at the retarded timing (FIG. 9). Reference).
- the output torque becomes the lower limit regardless of the cetane number of the fuel, and therefore, the cetane number of the fuel cannot be determined based on the output torque (specifically, the rotational fluctuation amount ⁇ NE).
- the control target value (target fuel injection timing TQsta) of the execution timing of the fuel injection is set based on the engine speed NE, and at the target fuel injection timing TQsta.
- the fuel injection is executed. More specifically, the target fuel injection timing TQsta is set to an advance timing as the engine speed NE is higher.
- the same fuel is produced in accordance with the engine rotational speed NE so that the fuel injection is executed in the execution region in which the output torque of the diesel engine 10 is less likely to be the upper limit or the lower limit.
- An injection execution timing (target fuel injection timing TQsta) can be set. Accordingly, since the rotational fluctuation amount ⁇ NE changes with a relatively wide range in accordance with the cetane number of the fuel, the cetane number of the fuel is accurately estimated based on the rotational fluctuation amount ⁇ NE. Will be able to.
- the fuel cetane number is estimated based on the index value of the output torque of the diesel engine 10 (specifically, the rotational fluctuation amount ⁇ NE). This is a cause of lowering the estimation accuracy of the price.
- the cooling water temperature THW and the supercharging pressure PA are used in addition to the engine rotational speed NE as setting parameters used for setting the target fuel injection timing TQsta.
- the coolant temperature THW is used as a value that serves as an index of the peak value of the temperature in the combustion chamber 11a of the diesel engine 10
- the supercharging pressure PA is an index of the peak value of the pressure in the combustion chamber 11a. Is used as a value.
- the lower the coolant temperature THW, the lower the peak temperature in the combustion chamber 11a, and the lower the supercharging pressure PA, the lower the peak pressure in the combustion chamber 11a, and the target fuel injection timing TQsta is on the advance side. Set to the time.
- the target fuel injection timing TQsta according to the coolant temperature THW and the supercharging pressure PA, when the peak temperature or peak pressure in the combustion chamber 11a of the diesel engine 10 is low, that is, the same injection timing and As the output torque of the diesel engine 10 generated when the fuel injection is performed with the injection amount is smaller, the fuel injection is performed earlier in order to increase the output torque. Therefore, even if the peak temperature and the peak pressure in the combustion chamber 11a are different in the execution of the fuel injection, the change in the output torque of the diesel engine 10 due to the difference is suppressed, so the output torque The cetane number of the fuel can be accurately estimated based on the index value (rotational fluctuation amount ⁇ NE).
- the needle valve 22 moves so as to close the injection hole 23 (FIG. 2) from which the fuel is ejected.
- the fuel passing through the nozzle valve 22 acts so as to prevent the needle valve 22 from moving to the injection hole 23 side. Therefore, the higher the kinematic viscosity of the fuel, the slower the moving speed of the needle valve 22, that is, the closing speed of the fuel injection valve 20. Therefore, even when the drive control of the fuel injection valve 20 is executed in a predetermined manner to inject a certain amount of fuel, the amount of fuel actually injected differs depending on the kinematic viscosity of the fuel. It becomes quantity. Such an error in the actual fuel injection amount due to the variation in the kinematic viscosity of the fuel contributes to a decrease in the estimation accuracy of the cetane number in the estimation control.
- the target fuel injection amount (specifically, the target fuel injection timing TQsta and the target fuel injection time TQtma) in the estimation control is corrected by the correction terms K1 to K3 calculated in the correction processing described above. I have to.
- the change is the fuel injection valve at the time of execution of fuel injection. 20 appears as a change in the fluctuation waveform (specifically, the detection time waveform) of the fuel pressure inside 20.
- correction terms K1 to K3 for making the detected time waveform coincide with the basic time waveform are calculated based on the difference between the detected time waveform and the basic time waveform.
- the target fuel injection timing TQsta and the target fuel injection time TQtma are corrected by the correction terms K1 to K3.
- the operating speed of the fuel injector 20 changes due to variations in the kinematic viscosity of the fuel
- the difference between the actual operating characteristic (detected time waveform) and the basic operating characteristic (basic time waveform) of the fuel injector 20 is different. Therefore, the injection amount error caused by the variation in the kinematic viscosity of the fuel can be suppressed.
- the fuel sensor 41 functioning as a pressure sensor is integrally attached to the fuel injection valve 20. Therefore, as compared with a device in which the fuel pressure is detected by a sensor provided at a position away from the fuel injection valve 20, the fuel pressure at a portion close to the injection hole 23 of the fuel injection valve 20 can be detected. Therefore, the fluctuation waveform of the fuel pressure in the fuel injection valve 20 accompanying the opening / closing operation can be detected with high accuracy. Therefore, the fluctuation waveform of the fuel pressure corresponding to the kinematic viscosity of the fuel at that time can be detected by the fuel sensor 41, and the target fuel injection amount can be corrected appropriately based on the fluctuation waveform. Become.
- the speed of propagation of the fluctuation wave becomes faster as the bulk modulus of the fuel is higher.
- the fuel pressure fluctuation mode inside the fuel injection valve 20 is detected by the fuel sensor 41
- the fluctuation wave of the fuel pressure associated with the opening or closing operation of the fuel injection valve 20 is caused by the position where the fuel sensor 41 is disposed.
- the time required to reach the value (the detection delay) varies depending on the bulk modulus of the fuel. Therefore, if the detection time waveform is detected based on the variation mode of the fuel pressure PQ detected by the fuel sensor 41, even if a certain amount of fuel is injected from the fuel injection valve 20, the detection time waveform is the same. However, the waveform varies depending on the bulk modulus of the fuel.
- the amount of fuel actually injected is determined by the volume elasticity of the fuel. The amount varies depending on the coefficient. Further, the error in the actual fuel injection amount due to the variation in the bulk modulus of the fuel also contributes to lowering the estimation accuracy of the cetane number in the estimation control, similarly to the error due to the kinematic viscosity of the fuel.
- the fuel temperature THQ is detected by the fuel sensor 41 immediately before the start of execution of fuel injection in the estimation control
- the correction term K4 is calculated based on the detected fuel temperature THQ, and the correction term K4 is used.
- the target fuel injection amount (specifically, the target fuel injection time TQtma) is corrected.
- the target fuel injection time TQtma is corrected based on such fuel temperature. For this reason, the relationship between the fluctuation waveform of the actual fuel pressure and the fluctuation waveform of the fuel pressure PQ detected by the fuel sensor 41 due to variations in the bulk modulus of the fuel becomes different. The error of the actual fuel injection amount due to the above can be suppressed.
- the fuel temperature THQ immediately before the start of fuel injection in the estimation control that is, the fuel temperature THQ detected at a timing close to the timing at which the fuel is actually injected is used for correcting the target fuel injection amount. Therefore, the target fuel injection amount can be accurately corrected in accordance with the bulk elasticity coefficient of the actually injected fuel.
- the fuel sensor 41 functioning as a temperature sensor is integrally attached to the fuel injection valve 20, a sensor provided at a position away from the fuel injection valve 20 (such as the fuel tank 32). Compared with the configuration for detecting the fuel temperature, a temperature close to the temperature of the actually injected fuel can be detected and used for correcting the target fuel injection amount in the estimation control. Therefore, the target fuel injection amount can be accurately corrected in accordance with the bulk elastic coefficient of the actually injected fuel.
- the injection amount error caused by the difference in the kinematic viscosity of the fuel is corrected by the correction terms K1 to K3 calculated based on the fluctuation waveform of the fuel pressure PQ, and calculated based on the fuel temperature THQ.
- the injection amount error is corrected separately such that the injection amount error due to the difference in the bulk modulus of the fuel is corrected by the correction term K4.
- both the injection amount error due to the kinematic viscosity of the fuel and the injection amount error due to the bulk modulus of the fuel are appropriately corrected. Therefore, an accurately adjusted amount of fuel is injected from the fuel injection valve 20, and the cetane number of the fuel can be accurately estimated based on the index value of the output torque of the diesel engine 10 obtained as a result. It becomes like this.
- the injection amount error due to the variation in the kinematic viscosity of the fuel and the injection amount error due to the variation in the bulk modulus of the fuel are accurately determined by the same correction value calculated based on a common calculation parameter such as the fuel temperature. If it can be corrected, it is preferable because this makes it possible to simplify the control structure.
- the increase in the injection amount error caused by the other may be larger than the decrease in the injection amount error caused by one of the kinematic viscosity and the bulk modulus of the fuel.
- corrections for these error factors must be corrected separately. It can be said that it is necessary to execute using parameters.
- the injection amount error due to the variation in the kinematic viscosity of the fuel is corrected based on the fluctuation waveform of the fuel pressure PQ, and the injection amount due to the variation in the bulk modulus of the fuel.
- Each injection amount error is corrected using a different correction parameter such that the error is corrected based on the fuel temperature THQ. Therefore, both of these injection amount errors can be corrected appropriately.
- the amount of heat generated is not always constant and the amount of generated heat may vary if the fuel production time and place differ. is there.
- Such variation in the amount of heat generated by the fuel causes variation in the output torque of the diesel engine 10 when the same amount of fuel is injected and supplied to the diesel engine 10 for combustion.
- the rotational fluctuation amount ⁇ NE the index value (specifically, the rotational fluctuation amount ⁇ NE) of the output torque of the diesel engine 10 generated by the execution of fuel injection at a predetermined amount. Therefore, even if the cetane number of the fuel is estimated based on the index value (specifically, the rotational fluctuation amount ⁇ NE) of the output torque of the diesel engine 10 generated by the execution of fuel injection at a predetermined amount, the rotational fluctuation amount ⁇ NE It cannot be distinguished whether the change is due to a difference in the cetane number of the fuel or a difference in the amount of generated heat, and the estimation cannot be made with high accuracy.
- the index value specifically, the rotational fluctuation amount ⁇ NE
- the amount of heat generated by the fuel has no correlation with the kinematic viscosity or bulk modulus of the fuel. Therefore, in the present embodiment, in order to properly correct the injection amount error due to the variation in the generated heat amount, it is necessary to perform the correction using a correction parameter different from the kinematic viscosity and the bulk modulus. I can say.
- FIGS. 10A and 10B show the relationship between the rotational fluctuation amount ⁇ NE, the rotational speed at the time of execution, and the fuel injection timing when the fuel injection is executed under the same fuel cetane number and injection amount. Indicates.
- FIG. 10 (a) shows the above relationship when a fuel with a large amount of generated heat is used
- FIG. 10 (b) shows the above relationship when a fuel with a small amount of generated heat is used.
- the upper limit of the rotational fluctuation amount ⁇ NE is a value when using a fuel with a large amount of generated heat (value indicated by “W1” in FIG. 10A) when using a fuel with a small amount of generated heat (FIG. 10 ( b) is larger than the value indicated by “W2” in FIG. Further, in this case, the upper limit of the rotational fluctuation amount ⁇ NE increases as the fuel with a larger amount of generated heat is used.
- an index value of the amount of heat generated due to fuel combustion is detected, and the cetane number is estimated based on the index value. Therefore, when fuel injection is performed at a predetermined injection amount in order to estimate the cetane number of fuel, the output torque of the diesel engine generated with the fuel injection changes due to variations in the amount of heat generated by the fuel. Nevertheless, it will be possible to estimate the cetane number while taking into account the effects of the change. Therefore, the estimation error of the cetane number due to the variation in the heat generation amount of the fuel can be suppressed to be small, and the cetane number of the fuel can be estimated with high accuracy.
- the execution procedure of the control (detection control) for detecting the amount of heat generated by the fuel will be specifically described.
- fuel injection for detecting the amount of heat generated by the fuel is executed apart from fuel injection for estimating the cetane number of fuel (fuel injection in the above-described estimation control).
- fuel injection in the detection control is executed prior to the fuel injection in the estimation control.
- an index value (specifically, the rotational fluctuation amount ⁇ NE) of the output torque of the diesel engine 10 generated as a result of the fuel injection is calculated, and the rotational fluctuation amount ⁇ NE is used as the index value of the generated heat amount. It is stored in the electronic control unit 40.
- the fuel injection amount in the detection control As the fuel injection amount in the detection control, a predetermined amount, that is, the same amount as the fuel injection amount in the estimation control is set. Therefore, the detection of the index value of the generated heat amount in the detection control and the calculation of the index value of the output torque in the estimation control can be performed based on the rotation fluctuation amount ⁇ NE obtained as a result of the combustion of the same amount of fuel. Therefore, the index value of the generated heat amount detected in the detection control can be easily used for estimating the cetane number in the estimation control.
- FIG. 11 shows the relationship between the cetane number of the fuel, the rotational fluctuation amount ⁇ NE, and the fuel injection timing under the same conditions for the fuel injection amount and the running rotational speed.
- the rotational fluctuation amount ⁇ NE is almost constant.
- There is a region that does not change region around arrow R in FIG. 11).
- the engine operating region is a region where the period of time during which the fuel is exposed to the high temperature and high pressure environment in the cylinder 11 of the diesel engine 10 becomes long, so that the unburned portion of the fuel becomes very small. It is done.
- the detection control of the present embodiment since the fuel injection is performed at such a time, the detection error due to the unburned portion of the fuel becomes very small. Therefore, the diesel engine 10 generated when a predetermined amount of fuel is burned. It becomes possible to accurately detect the index value of the output torque, and hence the generated heat quantity.
- the target injection timing TQstb in the detection control is set to a timing at which the actual fuel ignition timing becomes the compression top dead center (in this embodiment, BTDC 10 ° CA to 5 ° CA).
- the target injection timing TQstb and the target injection time TQtmb similarly to the fuel injection in the estimation control, as the setting parameters for the target injection amount (specifically, the target injection timing TQstb and the target injection time TQtmb), the coolant temperature THW, the supercharging pressure PA , And correction terms K1 to K4 are used. Specifically, by setting the target injection timing TQstb based on the cooling water temperature THW, an injection amount error due to variations in peak temperature in the combustion chamber 11a of the diesel engine 10 can be suppressed. In addition, by setting the target injection timing TQstb based on the supercharging pressure PA, an injection amount error due to variations in peak pressure in the combustion chamber 11a of the diesel engine 10 can be suppressed.
- FIG. 12 is a flowchart showing a specific execution procedure of the detection control process. Note that the series of processes shown in this flowchart conceptually shows the execution procedure of the detection control process, and the actual process is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.
- step S201 it is first determined whether or not an execution condition is satisfied.
- the execution condition is satisfied when all of the following [Condition A] to [Condition D] are satisfied.
- Control (so-called fuel cut control) is executed to temporarily stop fuel injection for operation of the diesel engine 10 while the traveling speed of the vehicle 1 and the engine rotational speed NE are decelerated by releasing the operation of the accelerator operation member. is being done.
- [Condition B] The clutch mechanism 2 is in an operating state in which the connection between the crankshaft 14 and the manual transmission 3 is released. Specifically, the clutch operating member is operated.
- the fuel in the return passage 35 is replaced with the fuel newly supplied from the fuel tank 32 after refueling based on the amount of fuel leaking from the inside of the fuel injection valve 20 into the return passage 35. Is detected, and with this detection, it is detected that the fuel in the fuel path has been replaced.
- the above [Condition D] is set for the following reason.
- the amount of heat generated and the cetane number of the fuel supplied to the diesel engine 10 may greatly change when the fuel tank 32 is refueled. Therefore, in order to efficiently detect the generated heat quantity of the fuel at an appropriate timing prior to estimation of the cetane number of the fuel, it is effective to execute the detection when the fuel tank 32 is refueled. It can be said that. However, immediately after the fuel tank 32 is refueled, the fuel before refueling remains in the fuel path. At this time, the above-described fuel injection is executed to detect the heat generated by the fuel. However, the value corresponding to the fuel after refueling cannot be detected as the amount of generated heat.
- step S201: NO When the execution condition is not satisfied (step S201: NO), this process is temporarily terminated without executing the following process, that is, a process for detecting the amount of heat generated by the fuel. Thereafter, when this process is repeatedly executed and the above execution condition is satisfied (step S201: YES), the target injection timing TQstb is set based on the engine speed NE, the coolant temperature THW, and the supercharging pressure PA at this time. (Step S202). Here, the higher the engine speed NE, the more advanced timing is set as the target injection timing TQstb.
- the fuel temperature THQ is detected by the fuel sensor 41, and the correction term K4 is calculated based on the fuel temperature THQ (step S203).
- the detection of the fuel temperature THQ by the fuel sensor 41 is performed immediately before the start of execution of fuel injection in the detection control (specifically, from when the execution condition is satisfied until the fuel injection is executed). Timing). For this reason, the fuel temperature THQ detected at a timing close to the timing at which the fuel is actually injected in the detection control can be used for correcting the target injection amount. Therefore, in accordance with the bulk elastic coefficient of the actually injected fuel. The target injection amount can be corrected with high accuracy.
- the detection of the fuel temperature THQ is performed after the fuel sensor 41 is temporarily switched to a state in which the fuel sensor 41 functions as a temperature sensor by a signal input from the electronic control unit 40.
- the relationship between the fuel temperature THQ and the correction term K4 that can accurately suppress the injection amount error due to the variation in the bulk modulus of the fuel is obtained in advance based on the results of experiments and simulations. It is stored in the control unit 40. In the process of step S203, the correction term K4 is set based on this relationship and the fuel temperature THQ.
- the area of the detection time waveform when the fuel injection valve 20 is driven in the same manner tends to be smaller as the fuel temperature is higher, that is, as the fuel bulk modulus is higher. There is. This is considered to be caused by the following. As the fuel temperature is higher and the bulk modulus of the fuel is higher, the propagation speed of the pressure fluctuation wave in the fuel injection valve 20 becomes faster. Therefore, the fluctuation wave of the fuel pressure accompanying the closing of the fuel injection valve 20 is detected by the fuel sensor 41. The arrangement position is reached early. As a result, the rising speed of the fuel pressure PQ detected by the fuel sensor 41 in the closing process of the fuel injection valve 20 increases, and the area of the detection time waveform decreases accordingly.
- the fuel injection amount from the fuel injection valve 20 is corrected to be increased in the fuel injection control so as to compensate for the area. Therefore, in the process of step S203, in order to suppress such a change in the fuel injection amount, a value that shortens the target injection time TQtmb as the fuel temperature THQ is higher is calculated as the correction term K4.
- the target injection amount (target injection timing TQstb and target injection time TQtmb) is corrected by the correction terms K1 to K3 calculated by the correction processing described above and the correction term K4 (step S204). Specifically, a value obtained by adding the correction term K1 to the target injection time TQstb is set as a new target injection time TQstb, and a value obtained by adding the correction terms K2, K3, K4 to the target injection time TQtmb is a new target injection time. Set as TQtmb.
- step S205 drive control of the fuel injection valve 20 based on the target injection timing TQstb and the target injection time TQtmb is executed, and fuel injection from the fuel injection valve 20 is executed (step S205).
- This fuel injection is performed using a predetermined one of the plurality of fuel injection valves 20 (in this embodiment, the fuel injection valve 20 attached to the cylinder 11 [# 1]).
- the correction terms K1 to K3 used in this process are also predetermined ones of the fuel injection valves 20 (in this embodiment, the fuel injection valves 20 attached to the cylinder 11 [# 1]). The value calculated corresponding to is used.
- an integrated value (a value corresponding to the area of the hatched portion in FIG. 13) for the change in the difference ⁇ NE accompanying the execution of the fuel injection is calculated, and this integrated value is calculated as the rotational fluctuation amount.
- ⁇ NE an integrated value for the change in the difference ⁇ NE accompanying the execution of the fuel injection is calculated, and this integrated value is calculated as the rotational fluctuation amount.
- the transition of the engine speed NE and the difference ⁇ NE shown in FIG. 13 is slightly different from the actual transition because it is simplified for easy understanding of the calculation method of the rotational fluctuation amount ⁇ NE.
- FIG. 14 is a flowchart showing a specific execution procedure of the estimation control process. Note that the series of processes shown in this flowchart conceptually shows the execution procedure of the estimation control process, and the actual process is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.
- step S301 it is first determined whether or not an execution condition is satisfied.
- the execution condition is satisfied when all of the [Condition A], [Condition B] and the following [Condition E] are satisfied.
- [Condition E] After determining that the fuel tank 32 has been refueled, there is a history of completion of detection of the amount of heat generated by the fuel in the detection control process.
- step S301: NO If the execution condition is not satisfied (step S301: NO), the present process is temporarily terminated without executing the following process, that is, a process for estimating the cetane number of the fuel. Thereafter, when this process is repeatedly executed and the above execution condition is satisfied (step S301: YES), the target fuel injection timing TQsta is set based on the engine speed NE, the coolant temperature THW, and the supercharging pressure PA at this time. (Step S302).
- step S303 the fuel temperature THQ is detected by the fuel sensor 41, and the correction term K4 is calculated based on the fuel temperature THQ (step S303).
- the detection of the fuel temperature THQ by the fuel sensor 41 is performed immediately before the start of execution of fuel injection in the estimation control (specifically, from when the execution condition is satisfied until the fuel injection is executed). Timing).
- a value that shortens the target fuel injection time TQtma as the fuel temperature THQ is higher is calculated as the correction term K4 in order to suppress the change in the fuel injection amount due to the variation in the bulk modulus of the fuel. Is done.
- the target fuel injection amount (target fuel injection timing TQsta and target fuel injection time TQtma) is corrected by the correction terms K1 to K3 calculated by the correction processing described above and the correction term K4 (step S304). Specifically, a value obtained by adding the correction term K1 to the target fuel injection timing TQsta is set as a new target fuel injection timing TQsta, and a value obtained by adding the correction terms K2, K3, K4 to the target fuel injection time TQtma is new. It is set as the target fuel injection time TQtma.
- step S305 drive control of the fuel injection valve 20 based on the target fuel injection timing TQsta and the target fuel injection time TQtma is executed, and fuel injection from the fuel injection valve 20 is executed (step S305).
- This fuel injection is performed using a predetermined one of the plurality of fuel injection valves 20 (in this embodiment, the fuel injection valve 20 attached to the cylinder 11 [# 1]).
- the correction terms K1 to K3 used in this process are also predetermined ones of the fuel injection valves 20 (in this embodiment, the fuel injection valves 20 attached to the cylinder 11 [# 1]). The value calculated corresponding to is used.
- an index value (the rotational fluctuation amount ⁇ NE) of the output torque of the diesel engine 10 generated with the fuel injection is calculated (step S306).
- an estimated value (estimated cetane number) of the cetane number of the fuel is calculated based on the rotation fluctuation amount ⁇ NE, the rotational speed at the time of execution, and the index value of the generated heat amount detected in the detection control process (step S307).
- the estimation control process is executed using a fuel with a predetermined amount of generated heat, it is possible to accurately estimate the cetane number of the fuel, and the estimated cetane number and the rotational fluctuation amount
- the relationship between ⁇ NE and the rotational speed at the time of execution (the relationship as shown in FIG.
- step S307 the relationship (estimated map) is corrected based on the difference between the actual generated heat amount grasped from the generated heat amount index value and a predetermined generated heat amount. Then, based on the corrected estimated map, the estimated cetane number is calculated based on the rotational fluctuation amount ⁇ NE and the execution rotational speed.
- the present process is temporarily terminated.
- various processes for fuel injection to the cylinder 11 [# 1].
- Various processes are executed on the basis of the output signals of the fuel sensors 41 corresponding to the cylinders 11 (# 1 to # 4) of the diesel engine 10 such as executing a control process and a correction process.
- a dedicated fuel sensor 41 provided for each cylinder 11. The amount of fuel injected from each fuel injection valve 20 can be accurately adjusted based on the fuel pressure PQ.
- the cetane number of the fuel is determined based on the output torque of the diesel engine 10 generated by the fuel injection. It becomes possible to estimate with high accuracy.
- the target injection amount for fuel injection in the detection control is corrected. Therefore, although the operating speed of the fuel injection valve 20 changes due to variations in the kinematic viscosity of the fuel, a deviation between the actual operating characteristics and the basic operating characteristics of the fuel injection valve 20 can be suppressed, and the kinematic viscosity of the fuel can be suppressed. It is possible to suppress the injection amount error caused by the variation in the above. Therefore, an accurately adjusted amount of fuel is injected from the fuel injection valve 20, and the amount of generated heat of the fuel can be detected accurately based on the index value of the output torque of the diesel engine 10 obtained as a result. .
- the target injection timing TQstb and the target injection time TQtmb are corrected by the correction terms K1 to K3 calculated based on the difference between the detection time waveform and the basic time waveform. Therefore, although the operating speed of the fuel injection valve 20 changes due to variations in the kinematic viscosity of the fuel, the deviation between the actual operating characteristics and the basic operating characteristics of the fuel injection valve 20 can be suppressed, and the kinematic viscosity of the fuel It is possible to suppress the injection amount error caused by the variation in the above.
- the target injection amount for fuel injection in the detection control is corrected. For this reason, the relationship between the fluctuation waveform of the actual fuel pressure and the fluctuation waveform of the fuel pressure PQ detected by the fuel sensor 41 due to variations in the bulk modulus of the fuel becomes different. The error of the actual fuel injection amount accompanying this can be suppressed. Therefore, it is possible to inject an amount of fuel that is accurately adjusted from the fuel injection valve 20 and to detect the amount of heat generated by the fuel based on the index value of the output torque of the diesel engine 10 obtained as a result.
- the target fuel injection amount for fuel injection in the estimation control is corrected. Therefore, an accurately adjusted amount of fuel is injected from the fuel injection valve 20, and the cetane number of the fuel can be accurately estimated based on the index value of the output torque of the diesel engine 10 obtained as a result. .
- the target fuel injection amount in the estimation control is corrected based on the fuel temperature THQ detected by the fuel sensor 41. Therefore, an accurately adjusted amount of fuel is injected from the fuel injection valve 20, and the cetane number of the fuel can be accurately estimated based on the index value of the output torque of the diesel engine 10 obtained as a result. .
- the target fuel injection timing TQsta and the target fuel injection time TQtma are corrected by the correction terms K1 to K3 calculated based on the difference between the detection time waveform and the basic time waveform. Therefore, it is possible to suppress an injection amount error in the estimation control due to the variation in the kinematic viscosity of the fuel.
- the fuel temperature THQ is detected immediately before the start of execution of fuel injection in the estimation control, and the target fuel injection amount in the estimation control is corrected based on the detected fuel temperature THQ.
- the target fuel injection amount can be accurately corrected according to the bulk modulus of the fuel.
- a configuration for setting the target fuel injection timing TQsta (or target injection timing TQstb) based on the coolant temperature THW and a configuration for setting the target fuel injection timing TQsta (or target injection timing TQstb) based on the supercharging pressure PA are omitted. May be.
- the rotational fluctuation amount ⁇ NE is corrected based on the coolant temperature THW
- the rotational fluctuation amount ⁇ NE is corrected based on the supercharging pressure PA
- the index value of the generated heat is detected (or the estimated cetane number).
- the coolant temperature THW and the supercharging pressure PA may be added to the parameters used for the calculation of (1).
- the amount of generated heat can be detected (or the estimated cetane number can be calculated) in accordance with the peak temperature and peak pressure in the combustion chamber 11a when fuel injection is performed, and the cetane number of the fuel can be accurately determined. Can be estimated.
- the configuration in which the target fuel injection timing TQsta is variably set according to the engine rotational speed NE may be omitted.
- the estimated cetane number can be calculated based on the rotational fluctuation amount ⁇ NE and the generated heat amount index value without using the rotational speed at execution as a calculation parameter. Specifically, fuel injection for estimating the cetane number of the fuel is performed at a predetermined engine speed NE, and the estimated cetane number is calculated based on the rotation fluctuation amount ⁇ NE calculated at this time. It may be.
- the estimated cetane number instead of correcting the estimated map based on the index value of the generated heat quantity, a plurality of calculation maps having different relationships depending on the index value of the generated heat quantity were prepared and detected The estimated cetane number may be calculated based on the relationship stored in the calculation map selected based on the generated heat quantity index value.
- the estimated map is corrected based on the generated heat quantity index value, and the estimated cetane number is calculated based on the output torque index value (rotational fluctuation amount ⁇ NE) from the corrected estimated map.
- the rotational fluctuation amount ⁇ NE may be corrected based on the index value of the generated heat quantity, and the estimated cetane number may be calculated from the estimation map based on the corrected rotational fluctuation amount ⁇ NE.
- the target fuel injection amount in the estimation control process is corrected based on the index value of the generated heat amount, and is estimated from the estimation map based on the rotational fluctuation amount ⁇ NE obtained as a result of the fuel injection based on the corrected target fuel injection amount.
- the cetane number may be calculated. Even with such a configuration, since the cetane number can be estimated based on the index value of the heat generation amount of the fuel, the estimation error of the cetane number due to the variation in the heat generation amount of the fuel can be suppressed to a small value.
- the process for detecting the index value of the heat generated by the fuel in the detection control may be executed prior to the process for calculating the rotational fluctuation amount ⁇ NE in the estimation control. Even with such a configuration, the estimated cetane number can be calculated based on the generated heat quantity index value and the rotational fluctuation amount ⁇ NE.
- the calculation of the estimated cetane number based on the index value (rotational fluctuation amount ⁇ NE) of the output torque of the diesel engine 10 may be performed based on an arithmetic expression instead of being performed based on the estimated map.
- the relationship between the estimated cetane number and the rotational fluctuation amount ⁇ NE may be stored in advance in the electronic control unit 40, and the estimated cetane number may be calculated based on the relationship.
- the timing for detecting the fuel temperature THQ as the calculation parameter of the correction term K4 is not limited to the timing immediately before the fuel injection in the detection control (or estimation control) is performed, and can be changed to any timing. In short, it is sufficient that the temperature of the injected fuel can be accurately grasped prior to the execution of fuel injection in detection control (or estimation control). Specifically, for example, the fuel temperature THQ detected during execution of other engine control such as fuel injection control can be used as a calculation parameter for the correction term K4.
- the process for calculating the correction term K4 and the process for correcting the target fuel injection time TQtma and the target injection time TQtmb based on the correction term K4 may be omitted.
- the cetane number estimation apparatus according to the embodiment can be applied to an apparatus in which only the correction terms K1 and K2 are calculated without calculating the correction term K3 in the fuel injection control.
- the target injection amount in the detection control and the target fuel injection amount in the estimation control are corrected by the correction terms K1 to K3 calculated in the fuel injection control.
- a dedicated fuel injection for calculating a correction term for correcting the target injection amount in the detection control and the target fuel injection amount in the estimation control is executed, and the fuel injection valve at the time of executing the fuel injection is executed.
- the correction term may be calculated based on the difference between the 20 actual operation characteristics (detection time waveform) and a predetermined basic operation characteristic (basic time waveform).
- the correction term can be calculated based on the difference between the completion timing of the closing operation in the actual operation characteristics of the fuel injection valve 20 and the completion timing of the closing operation of the fuel injection valve 20 in the basic operation characteristics. it can.
- the higher the kinematic viscosity of the fuel the slower the valve closing speed of the fuel injection valve 20. Therefore, when the valve closing operation of the fuel injection valve 20 changes due to variations in the kinematic viscosity of the fuel, the change appears as a difference in the completion timing of the valve closing operation between the actual operation characteristics and the basic operation characteristics of the fuel injection valve 20. It becomes like this.
- the difference in completion timing of the valve closing operation is used as an index value for the kinematic viscosity of the fuel to correct the target injection amount in the detection control processing and the target fuel injection amount in the estimation control processing.
- the correction term can be calculated. For this reason, it is possible to suppress the injection amount error caused by the variation in the kinematic viscosity of the fuel based on the correction value.
- values corresponding to the correction terms K1 to K3 can be calculated. In short, any value that can appropriately suppress the deviation between the actual operating characteristic and the basic operating characteristic of the fuel injection valve 20 can be adopted as the correction term.
- the cetane number estimation device can be applied not only to the vehicle 1 on which the clutch mechanism 2 and the manual transmission 3 are mounted, but also to a vehicle on which a torque converter and an automatic transmission are mounted. it can.
- the fuel injection for detecting the amount of heat generated by the fuel and the fuel injection for estimating the cetane number may be executed.
- a value other than the rotational fluctuation amount ⁇ NE may be calculated as an index value of the output torque of the diesel engine 10. For example, during execution of detection control and estimation control, an engine rotational speed NE (running rotational speed) when fuel injection is performed and an engine rotational speed NE when fuel injection is not performed are detected and the difference between these speeds is detected. The difference can be calculated and used as the index value.
- a value other than the rotational fluctuation amount ⁇ NE may be detected as an index value of the generated heat amount.
- the peak temperature or peak pressure in the cylinder 11 of the diesel engine 10 when a predetermined amount of fuel is injected may be detected and stored in the electronic control unit 40 as an index value for the amount of generated heat.
- the fuel injection amount in detection control and the fuel injection amount in estimation control may be set to different amounts.
- the coolant temperature THW as a setting parameter for the target fuel injection timing TQsta and the target injection timing TQstb
- the temperature of the diesel engine 10 specifically, its cylinder head or cylinder block
- the temperature of intake air etc.
- a value other than the coolant temperature THW that is an index of the peak temperature in the combustion chamber 11a can also be used. It is also possible to directly detect the temperature in the combustion chamber 11a and use it as the setting parameter.
- the supercharging pressure PA as a setting parameter for the target fuel injection timing TQsta and the target injection timing TQstb
- a value that is an index of the peak pressure in the combustion chamber 11a such as the pressure of intake air or the pressure of the atmosphere.
- a value other than the supercharging pressure PA can also be used. It is also possible to directly detect the pressure in the combustion chamber 11a and use it as the setting parameter.
- Such a configuration can also be applied to a diesel engine in which the supercharger 16 is not provided. Even in a diesel engine that is not provided with the supercharger 16, the peak pressure in the combustion chamber 11a is slightly different depending on the operating state or operating environment of the diesel engine, and therefore is based on the peak pressure (or its index value). Thus, by correcting the injection timing, it is possible to improve the estimation accuracy of the cetane number of the fuel.
- the method of determining that the fuel tank 32 has been refueled is not limited to the method of determining based on the detection signal of the stockpiling amount sensor 45, and is determined based on whether the lid of the fuel tank 32 is opened or closed. Any method such as a method can be adopted.
- the method of determining that the fuel in the fuel path has been replaced is not limited to the method of determining based on the amount of fuel leaking from the inside of the fuel injection valve 20 to the return passage 35, and for example, supplied to the fuel injection valve 20 Arbitrary methods, such as a method of judging based on the amount of fuel and a method of judging based on the amount of fuel injected from the fuel injection valve 20, can be adopted.
- the execution conditions in the detection control process can be arbitrarily changed.
- the execution conditions in the estimation control process can be arbitrarily changed. For example, instead of [Condition D], it is also possible to set [Condition F] that “a predetermined time has elapsed after it is determined that the fuel tank 32 has been refueled”. According to this [Condition F], it is possible to determine that the fuel in the fuel path has been replaced, as in [Condition D], by setting a relatively short time as the predetermined time.
- the environment is such that the detection of the amount of heat generated from the fuel and the estimation of the cetane number based on NE (specifically, the rotational fluctuation amount ⁇ NE) can be executed with high accuracy.
- the [Condition G] it is possible to execute a process for detecting the amount of heat generated in the fuel and a process for estimating the cetane number in such an environment.
- the cetane number of the fuel used when starting the diesel engine 10 can be accurately estimated, the starting performance of the diesel engine 10 can be improved. It should be noted that the satisfaction of [Condition G] can be determined by the operation switch being operated by the occupant to stop the operation of the diesel engine 10.
- a pressure sensor and a temperature sensor may be provided separately.
- the pressure sensor is attached in the same configuration in accordance with a change in the fuel pressure inside the fuel injection valve 20 (specifically, in the nozzle chamber 25), in other words, the fuel pressure inside the fuel injection valve 20.
- the fuel pressure is not limited to being directly attached to the fuel injection valve 20, but can be arbitrarily changed.
- the pressure sensor may be attached to the branch passage 31 a or the common rail 34.
- the manner of attaching the temperature sensor in the above configuration is not limited to the manner of being directly attached to the fuel injector 20 as long as the temperature of the fuel actually injected from the fuel injector 20 can be properly detected. Can be changed.
- the temperature sensor may be attached to the branch passage 31 a or the common rail 34.
- a fuel injection valve driven by the piezoelectric actuator 29 for example, a fuel injection valve driven by an electromagnetic actuator provided with a solenoid coil or the like may be employed.
- the present invention is not limited to a diesel engine having four cylinders, but also to a single cylinder diesel engine, a diesel engine having two cylinders, a diesel engine having three cylinders, or a diesel engine having five or more cylinders. Can be applied.
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Abstract
Description
本発明の目的は、燃料のセタン価を精度よく推定することのできるセタン価推定装置を提供することにある。
好ましい態様は、前記装置は、温度センサによる燃料温度の検出を発生熱量の検出のための燃料噴射の実行開始直前において行うものである。
圧力センサは燃料噴射弁に取り付けられるのが好ましい。
図1に示すように、車両1には、駆動源としてのディーゼル機関10が搭載されている。ディーゼル機関10のクランクシャフト14は、クラッチ機構2、手動変速機3を介して車輪4に連結されている。車両1では乗員によってクラッチ操作部材(例えばクラッチペダル)が操作されると、上記クラッチ機構2がクランクシャフト14と手動変速機3との連結を解除する作動状態になる。
図2に示すように、燃料噴射弁20のハウジング21の内部にはニードル弁22が設けられている。このニードル弁22はハウジング21内において往復移動(同図の上下方向に移動)することの可能な状態で設けられている。ハウジング21の内部には上記ニードル弁22を噴射孔23側(同図の下方側)に常時付勢するスプリング24が設けられている。またハウジング21の内部には、上記ニードル弁22を間に挟んで一方側(同図の下方側)の位置にノズル室25が形成されており、他方側(同図の上方側)の位置に圧力室26が形成されている。
先ず、アクセル操作量ACCや機関回転速度NE、燃料のセタン価(詳しくは、後述する推定セタン価)などに基づいて、機関運転のための燃料噴射量についての制御目標値(要求噴射量TAU)が算出される。その後、要求噴射量TAUおよび機関回転速度NEに基づいて燃料噴射時期の制御目標値(要求噴射時期Tst)や燃料噴射時間の制御目標値(要求噴射時間Ttm)が算出される。そして、それら要求噴射時期Tstおよび要求噴射時間Ttmに基づいて各燃料噴射弁20の開弁駆動が実行される。これにより、そのときどきのディーゼル機関10の運転状態に見合う量の燃料が各燃料噴射弁20から噴射されてディーゼル機関10の各気筒11内に供給されるようになる。
図3に、燃料圧力PQの推移と燃料噴射率の検出時間波形との関係を示す。
なお図4は上記補正処理の具体的な手順を示すフローチャートであり、同フローチャートに示される一連の処理は所定周期毎の割り込み処理として電子制御ユニット40により実行される。また、図5および図6は、検出時間波形と基本時間波形との関係の一例をそれぞれ示している。
燃料噴射制御の実行に際しては、要求噴射時期Tstを補正項K1によって補正した値(本実施の形態では、要求噴射時期Tstに補正項K1を加算した値)が最終的な要求噴射時期Tstとして算出される。このようにして要求噴射時期Tstを算出することにより、基本時間波形における開弁動作開始時期Tosbと検出時間波形における開弁動作開始時期Tosbとの間のずれが小さく抑えられるようになるため、燃料噴射の開始時期がディーゼル機関10の運転状態に応じたかたちで精度よく設定されるようになる。
この推定制御は基本的には次のように実行される。すなわち先ず、実行条件の成立時において、予め定められた所定量(例えば、数立方ミリメートル)での燃料噴射が実行されるとともに、その燃料噴射の実行に伴い発生するディーゼル機関10の出力トルクの指標値(後述する回転変動量ΣΔNE)が算出される。そして、この回転変動量ΣΔNEに基づいて燃料のセタン価が推定される。ディーゼル機関10に供給される燃料のセタン価が高いときほど、燃料が着火し易く同燃料の燃え残りが少なくなるために、燃料の燃焼に伴って発生する機関トルクが大きくなる。本実施の形態の推定制御では、そうした燃料のセタン価とディーゼル機関10の出力トルクとの関係をもとに同燃料のセタン価が推定される。
所定量での燃料噴射の実行に伴い発生するディーゼル機関10の出力トルクには上限(詳しくは、燃料の燃え残りが「0」のときの出力トルク)がある。上記出力トルクが上限になる領域は、機関回転速度NEが低い状況で上記燃料噴射が実行される領域や(図8参照)、進角側の時期において上記燃料噴射が実行される領域(図9参照)である。そうした領域においては、燃料のセタン価によることなくディーゼル機関10の出力トルクが上限になってしまうために、同出力トルク(詳しくは、回転変動量ΣΔNE)をもとに燃料のセタン価を判別することができない。
先ず、燃料のセタン価の推定のための燃料噴射(前述した推定制御における燃料噴射)とは別に、燃料の発生熱量の検出のための燃料噴射が実行される。この検出制御における燃料噴射は、推定制御における燃料噴射に先立ち実行される。そして検出制御では、燃料噴射の実行に伴い発生するディーゼル機関10の出力トルクの指標値(詳しくは、回転変動量ΣΔNE)が算出されるとともに、その回転変動量ΣΔNEが上記発生熱量の指標値として電子制御ユニット40に記憶される。
ここでは先ず、図12を参照しつつ検出制御処理の実行手順について詳細に説明する。
[条件A]アクセル操作部材の操作解除による車両1の走行速度および機関回転速度NEの減速中においてディーゼル機関10の運転のための燃料噴射を一時的に停止させる制御(いわゆる燃料カット制御)が実行されていること。
[条件B]クラッチ機構2がクランクシャフト14と手動変速機3との連結を解除する作動状態になっていること。具体的には、クラッチ操作部材が操作されていること。
[条件C]燃料タンク32への燃料補給が行われたと判定された後に、燃料の発生熱量の検出が完了した履歴がないこと。なお燃料タンク32への燃料補給が行われたことは、備蓄量センサ45により検出される燃料備蓄量が所定の判定量以上増加したことをもって判定される。本処理では、この[条件C]が設定されているために、燃料の発生熱量の検出が燃料補給の実行の度に一度のみ実行される。
[条件D]燃料タンク32への燃料補給が行われたと判定された後に、燃料タンク32から新たに供給された燃料によって同燃料タンク32と燃料噴射弁20とを繋ぐ燃料経路(詳しくは、分岐通路31aや供給通路31b、コモンレール34、リターン通路35により構成される経路)内の燃料が置換されたこと。
その後、本処理が繰り返し実行されて上記実行条件が成立すると(ステップS201:YES)、このときの機関回転速度NE、冷却水温度THW、および過給圧PAに基づいて目標噴射時期TQstbが設定される(ステップS202)。ここでは機関回転速度NEが高いときほど、目標噴射時期TQstbとして進角側の時期が設定される。
図14は、上記推定制御処理の具体的な実行手順を示すフローチャートである。なお、このフローチャートに示される一連の処理は、推定制御処理の実行手順を概念的に示したものであり、実際の処理は所定周期毎の割り込み処理として電子制御ユニット40により実行される。
[条件E]燃料タンク32への燃料補給が行われたと判定された後に、前記検出制御処理において燃料の発生熱量の検出が完了した履歴があること。
その後、本処理が繰り返し実行されて上記実行条件が成立すると(ステップS301:YES)、このときの機関回転速度NE、冷却水温度THW、および過給圧PAに基づいて目標燃料噴射時期TQstaが設定される(ステップS302)。
そして、回転変動量ΣΔNEと実行時回転速度と検出制御処理において検出された発生熱量の指標値とに基づいて、燃料のセタン価の推定値(推定セタン価)が算出される(ステップS307)。なお本実施の形態では、所定の発生熱量の燃料を使用して推定制御処理を実行した場合に燃料のセタン価を精度よく推定することの可能な関係であり、且つ推定セタン価と回転変動量ΣΔNEと実行時回転速度との関係(図8に示すような関係)が実験やシミュレーションの結果をもとに予め求められて電子制御ユニット40に記憶されている。ステップS307の処理では、上記発生熱量の指標値により把握される実際の発生熱量と所定の発生熱量との差に基づいて上記関係(推定マップ)が補正される。そして、その補正後の推定マップをもとに回転変動量ΣΔNEと上記実行時回転速度とに基づいて推定セタン価が算出される。
本実施の形態にかかる装置では、例えばディーゼル機関10の気筒11[♯1]に設けられた燃料センサ41の検出信号に基づいて同気筒11[♯1]に対する燃料噴射についての各種処理(燃料噴射制御にかかる処理や補正処理)を実行するなどといったように、ディーゼル機関10の気筒11(♯1~♯4)毎にそれぞれ対応する燃料センサ41の出力信号に基づいて各種処理が実行される。そのため、初期個体差や経時変化の相違に起因して燃料噴射弁20の作動特性が気筒11毎に異なる多気筒のディーゼル機関10において、気筒11毎に設けられた専用の燃料センサ41により検出される燃料圧力PQに基づいて各燃料噴射弁20から噴射される燃料の量をそれぞれ精度良く調節することができる。
(1)燃料の燃焼に伴う発生熱量の指標値を検出するとともに、同指標値に基づいてセタン価を推定するようにした。そのため、燃料の発生熱量のばらつきに起因するセタン価の推定誤差を小さく抑えることができ、燃料のセタン価を精度よく推定することができるようになる。
・冷却水温度THWに基づいて目標燃料噴射時期TQsta(または目標噴射時期TQstb)を設定する構成や過給圧PAに基づいて目標燃料噴射時期TQsta(または目標噴射時期TQstb)を設定する構成を省略してもよい。なお、この場合には冷却水温度THWに基づいて回転変動量ΣΔNEを補正したり、過給圧PAに基づいて回転変動量ΣΔNEを補正したり、発生熱量の指標値の検出(あるいは推定セタン価の算出)に用いるパラメータに冷却水温度THWや過給圧PAを加えたりしてもよい。こうした構成によっても、燃料噴射の実行時における燃焼室11a内のピーク温度やピーク圧力に応じたかたちで発生熱量を検出(あるいは推定セタン価を算出)することができ、燃料のセタン価を精度よく推定することができる。
・実施の形態にかかるセタン価推定装置は、燃料噴射制御において補正項K3が算出されずに補正項K1,K2のみが算出される装置にも適用することができる。
・目標燃料噴射時期TQstaや目標噴射時期TQstbの設定パラメータとして冷却水温度THWを用いることに代えて、例えばディーゼル機関10(詳しくは、そのシリンダヘッドやシリンダブロック)の温度や吸入空気の温度など、燃焼室11a内のピーク温度の指標になる値であって冷却水温度THW以外の値を用いることもできる。また、燃焼室11a内の温度を直接検出してこれを上記設定パラメータとして用いることもできる。
Claims (14)
- ディーゼル機関の燃焼に供される燃料のセタン価を推定するべく予め定めた噴射量での燃料噴射を実行するセタン価推定装置であって、
前記燃料の燃焼に伴う発生熱量の指標値を検出するとともに前記予め定めた噴射量での燃料噴射の実行に伴い発生する前記ディーゼル機関の出力トルクの指標値を算出し、それら指標値に基づいて前記セタン価を推定する
ことを特徴とするセタン価推定装置。 - 請求項1に記載のセタン価推定装置において、
当該装置は、前記セタン価の推定値と前記出力トルクの指標値との関係を予め記憶しており、前記発生熱量の指標値に基づいて前記関係を補正するとともに、その補正した関係と前記出力トルクの指標値とに基づいて前記セタン価の推定値を算出する
ことを特徴とするセタン価推定装置。 - 請求項1に記載のセタン価推定装置において、
当該装置は、前記セタン価の推定値と前記出力トルクの指標値との関係を予め記憶しており、前記発生熱量の指標値に基づいて前記出力トルクの指標値を補正するとともに、その補正した指標値と前記関係とに基づいて前記セタン価の推定値を算出する
ことを特徴とするセタン価推定装置。 - 請求項1に記載のセタン価推定装置において、
当該装置は、前記発生熱量の指標値に応じて補正した噴射量に基づき前記セタン価の推定のための燃料噴射を実行するとともに、同燃料噴射の実行に伴い算出した前記出力トルクの指標値に基づいて前記セタン価を推定する
ことを特徴とするセタン価推定装置。 - 請求項1~4のいずれか一項に記載のセタン価推定装置において、
当該装置は、前記燃料の発生熱量を検出するべく予め定めた噴射量での燃料噴射を実行するとともに同燃料噴射の実行に伴い発生する前記ディーゼル機関の出力トルクの指標値を算出し、その算出した指標値を前記発生熱量の指標値とする
ことを特徴とするセタン価推定装置。 - 請求項5に記載のセタン価推定装置において、
当該装置は、前記発生熱量の検出のための燃料噴射を目標噴射量に基づき実行するものであり、
燃料噴射弁内部の燃料圧力の指標となる燃料圧力を検出する圧力センサをさらに備え、燃料噴射時に前記圧力センサによって検出された燃料圧力の変動波形に基づいて前記目標噴射量を補正する
ことを特徴とするセタン価推定装置。 - 請求項6に記載のセタン価推定装置において、
当該装置は、前記検出した燃料圧力の変動波形に基づいて前記燃料噴射弁の実動作特性を算出するとともに、該算出した実動作特性と予め定められた基本動作特性との差に基づいて前記目標噴射量を補正する
ことを特徴とするセタン価推定装置。 - 請求項5~7のいずれか一項に記載のセタン価推定装置において、
当該装置は、前記発生熱量の検出のための燃料噴射を目標噴射量に基づき実行するものであり、
前記燃料の温度を温度センサにより検出するとともに、その検出した燃料温度に基づいて前記目標噴射量を補正する
ことを特徴とするセタン価推定装置。 - 請求項8に記載のセタン価推定装置において、
当該装置は、前記温度センサによる燃料温度の検出を前記発生熱量の検出のための燃料噴射の実行開始直前において行うものである
ことを特徴とするセタン価推定装置。 - 請求項1~9のいずれか一項に記載のセタン価推定装置において、
当該装置は、前記セタン価の推定のための燃料噴射を目標燃料噴射量に基づき実行するものであり、
燃料噴射弁内部の燃料圧力の指標となる燃料圧力を検出する圧力センサをさらに備え、燃料噴射時に前記圧力センサによって検出された燃料圧力の変動波形に基づいて前記目標燃料噴射量を補正する
ことを特徴とするセタン価推定装置。 - 請求項10に記載のセタン価推定装置において、
当該装置は、前記検出した燃料圧力の変動波形に基づいて前記燃料噴射弁の実動作特性を算出するとともに、該算出した実動作特性と予め定められた基本動作特性との差に基づいて前記目標燃料噴射量を補正する
ことを特徴とするセタン価推定装置。 - 請求項1~11のいずれか一項に記載のセタン価推定装置において、
当該装置は、前記セタン価の推定のための燃料噴射を目標燃料噴射量に基づき実行するものであり、
前記燃料の温度を温度センサにより検出するとともに、その検出した燃料温度に基づいて前記目標燃料噴射量を補正する
ことを特徴とするセタン価推定装置。 - 請求項12に記載のセタン価推定装置において、
当該装置は、前記温度センサによる燃料温度の検出を前記セタン価の推定のための燃料噴射の実行開始直前において行うものである
ことを特徴とするセタン価推定装置。 - 請求項6または7または10または11に記載のセタン価推定装置において、
前記圧力センサは前記燃料噴射弁に取り付けられている
ことを特徴とするセタン価推定装置。
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PCT/JP2011/052656 WO2012108005A1 (ja) | 2011-02-08 | 2011-02-08 | セタン価推定装置 |
BR112013016384A BR112013016384B1 (pt) | 2011-02-08 | 2011-02-08 | dispositivo para estimativa do número de cetano |
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JP5316525B2 (ja) * | 2010-12-07 | 2013-10-16 | トヨタ自動車株式会社 | セタン価推定装置 |
US9556845B2 (en) * | 2013-03-12 | 2017-01-31 | Ecomotors, Inc. | Enhanced engine performance with fuel temperature control |
JP6087726B2 (ja) * | 2013-05-23 | 2017-03-01 | トヨタ自動車株式会社 | 燃料噴射特性検出装置 |
DE102013216192B4 (de) * | 2013-08-14 | 2020-08-06 | Mtu Friedrichshafen Gmbh | Verfahren zur Bestimmung von wenigstens einem Einspritzparameter einer Brennkraftmaschine und Brennkraftmaschine |
JP6032244B2 (ja) * | 2014-05-29 | 2016-11-24 | 株式会社デンソー | 燃料性状判定装置、及び燃料性状判定方法 |
JP6168016B2 (ja) * | 2014-09-02 | 2017-07-26 | 株式会社デンソー | 燃料密度検出装置 |
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GB2552187A (en) | 2016-07-13 | 2018-01-17 | Gm Global Tech Operations Llc | A method of operating an internal combustion engine |
JP2018031340A (ja) * | 2016-08-26 | 2018-03-01 | マツダ株式会社 | エンジンの燃料性状判定装置および燃焼制御装置 |
JP7243577B2 (ja) * | 2019-11-06 | 2023-03-22 | トヨタ自動車株式会社 | 車両用制御装置 |
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US9127608B2 (en) | 2015-09-08 |
CN103354866A (zh) | 2013-10-16 |
JP5790666B2 (ja) | 2015-10-07 |
BR112013016384B1 (pt) | 2019-11-26 |
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