WO2013014736A1

WO2013014736A1 - Control device of internal combustion engine

Info

Publication number: WO2013014736A1
Application number: PCT/JP2011/066822
Authority: WO
Inventors: 広孝金子
Original assignee: トヨタ自動車株式会社
Priority date: 2011-07-25
Filing date: 2011-07-25
Publication date: 2013-01-31
Also published as: CN103026033B; BR112012015464B1; JPWO2013014736A1; JP5224004B1; CN103026033A; DE112011105465T5; BR112012015464A2; DE112011105465B4

Abstract

An electronic control unit separately executes basic injection control by which fuel is injected at an amount corresponding to the operating state of an internal combustion engine, and auxiliary injection control by which fuel is injected to detect the cetane number index value of fuel on the condition that an execution condition has been met. The electronic control unit stores, as a first index value (S1), a rotational fluctuation amount (ΣΔNE) obtained as the result of fuel injection implemented by the auxiliary injection control, and also executes the basic injection control on the basis of the stored first index value (S1). When a fuel tank is replenished with fuel (301: YES), the electronic control unit calculates and stores a second index value (VS) on the basis of the first index value (S1), a pre-replenishment storage amount (V1) and a fuel supply amount (V2) (S302), and also executes the basic injection control on the basis of the second index value (VS).

Description

Control device for internal combustion engine

The present invention relates to a control device for an internal combustion engine that estimates the cetane number of fuel supplied to the internal combustion engine and executes engine operation control according to the estimated cetane number.

In the self-ignition type internal combustion engine, the fuel injected into the cylinder by the fuel injection valve is ignited after a predetermined time (so-called ignition delay) has elapsed since the injection. In order to improve the output performance and emission performance of an internal combustion engine, a control device that controls the execution mode of engine control such as injection timing and injection amount in fuel injection in consideration of such ignition delay is widely adopted. .

In internal combustion engines, the lower the cetane number of the fuel used, the longer the ignition delay. For this reason, for example, even if the engine control execution mode is set assuming that a standard cetane number fuel is used at the time of shipment of the internal combustion engine, a fuel with a relatively low cetane number such as winter fuel is used as a fuel tank. When the fuel is replenished, the ignition timing of the fuel is delayed and the combustion state is deteriorated. In some cases, misfire occurs.

In order to suppress the occurrence of such inconvenience, it is desirable to correct the engine control execution mode based on the actual cetane number of the fuel injected into the cylinder. In order to suitably perform such correction, it is necessary to accurately estimate the cetane number of the fuel.

Conventionally, in Patent Document 1, when a small amount of fuel is injected from the fuel injection valve when the execution condition is satisfied, an index value of the engine torque generated by the execution is detected, and based on the index value, the fuel An apparatus for estimating the cetane number has been proposed. In this apparatus, focusing on the fact that the engine torque generated by a predetermined amount of fuel injection changes according to the cetane number of the fuel, the cetane number of the fuel is estimated based on the index value of the engine torque generated by the fuel injection. The

JP 2010-24870 A JP 2007-239738 A

By the way, in the apparatus described in Patent Document 1, since fuel injection for estimating the cetane number is executed only when the execution condition is satisfied, fuel supply is performed and the cetane number of the fuel in the fuel tank changes. Even if there is a possibility that the cetane number is not estimated unless the execution condition is satisfied, the state where the cetane number is not estimated is continued. In this case, if the low cetane number fuel is replenished in a situation where the estimation result before refueling is high cetane number and the cetane number of the fuel in the fuel tank is low, the fuel supplied to the internal combustion engine is low in cetane number. In spite of the fuel, the operation control of the internal combustion engine is executed in the execution mode suitable for the high cetane number fuel. In this case, not only the combustion state of the fuel in the cylinder of the internal combustion engine is deteriorated but also misfire is caused in some cases.

Such inconvenience is not limited to a device that performs fuel injection for estimating the cetane number on the condition that the execution condition described above is satisfied, and the cetane number index value after the refueling is a value that matches the actual cetane number. It can occur in the same manner as long as it takes time to become. As such a device, for example, a device described in Patent Document 2 can be cited. In this apparatus, the ignition delay time is calculated based on the pressure in the cylinder of the internal combustion engine detected by the in-cylinder pressure sensor, and the cetane number of the fuel is estimated based on the ignition delay time. This apparatus also describes that averaged data is used for cetane number estimation in order to improve the accuracy of centering estimation. In such an apparatus, it takes time until the index value of the cetane number becomes a value corresponding to the actual cetane number after refueling, and therefore, the combustion state of the fuel is deteriorated immediately after refueling.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for an internal combustion engine capable of suppressing the occurrence of misfire caused by replenishment of low cetane number fuel.

In order to achieve the above object, in the control device for an internal combustion engine according to the present invention, the cetane number index value of the fuel supplied to the internal combustion engine is calculated and the same value is stored as the first index value. Further, combustion control relating to fuel combustion is executed based on the first index value. The combustion control is engine control for adjusting the combustion state of the fuel in the cylinder of the internal combustion engine, such as fuel injection control or EGR control.

In the above device, when fuel is replenished, that is, when the cetane number of the stored fuel in the fuel tank has changed, there is a possibility that the first index value and the value corresponding to the actual cetane number have greatly deviated. Combustion control is executed based on the second index value calculated as follows. That is, based on the relationship between the amount of fuel stored in the fuel tank at the start of fuel supply, the first index value stored at the start of fuel supply, and the amount of fuel supplied to the fuel tank, The cetane number index value (second index value) is calculated and stored. By calculating the second index value in this way, the cetane of the fuel in the fuel tank after refueling under the assumption that the cetane number of the fuel replenished to the fuel tank is a predetermined value. The value can be estimated. Therefore, by defining an appropriate value (for example, the lowest cetane number in the assumed range) as the predetermined value, a value that serves as an index of the lower limit of the change range of the fuel cetane number in the fuel tank after refueling as the second index value Can be calculated.

According to the above apparatus, it is possible to grasp how low the cetane number of the fuel in the fuel tank after refueling may be based on the second index value. Therefore, by executing the combustion control based on the second index value, it is estimated before refueling when the cetane number of the fuel in the fuel tank (that is, fuel supplied to the internal combustion engine) becomes low by refueling. It is possible to suppress the situation in which the combustion control is executed in an execution mode suitable for the relatively high cetane number index value (first index value). Therefore, even when a low cetane number fuel is supplied to the fuel tank, it is possible to suppress the occurrence of misfire due to the fuel supply.

In one aspect of the present invention, the amount of fuel stored in the fuel tank at the start of refueling is “V1”, the first index value stored at the start of refueling is “S1”, and the fuel tank Assuming that the amount of fuel replenished is “V2” and a predetermined predetermined cetane number index value is “S2”, the second index value VS is [VS = (V1 × S1 + V2 × S2) / (V1 + V2) ] Is calculated to satisfy the relationship.

In a preferred embodiment, the predetermined cetane number index value S2 is set as the index value of the lowest cetane number among the cetane numbers of fuels that may be replenished to the fuel tank. According to such an apparatus, based on the above relationship, the cetane of the fuel in the fuel tank after refueling when the fuel having the lowest cetane number among the fuels that may be replenished to the fuel tank is replenished. The index value of the value can be calculated as the second index value VS, and the combustion control can be executed based on the second index value VS. Therefore, when the cetane number of the fuel supplied to the internal combustion engine is reduced by refueling, it is possible to accurately suppress the situation where the combustion control is executed in an execution mode commensurate with a relatively high cetane number.

In one aspect of the present invention, when the first index value is newly stored by the storage unit after the fuel tank is refueled, the second control unit stops executing the combustion control based on the second index value. Then, the first control unit starts executing the combustion control based on the first index value. According to such an apparatus, even when the fuel tank is refueled and the cetane number of the fuel stored in the fuel tank changes, the first index value is newly calculated and stored. Thereafter, the combustion control can be executed in accordance with the first index value, that is, the actual cetane number index value of the fuel.

In one aspect of the present invention, fuel injection for detecting a cetane number index value of fuel on condition that an execution condition is satisfied, separately from basic injection control in which fuel injection is performed in an amount corresponding to the operating state of the internal combustion engine. The cetane number index value obtained as a result of the fuel injection by the auxiliary injection control is stored as the first index value.

In one aspect of the present invention, the execution condition includes a condition that execution of fuel injection by the basic injection control is temporarily stopped. Normally, during the operation of the internal combustion engine, the temporary stop of the fuel injection by the basic injection control is executed in a limited situation, for example, when the rotational speed of the engine output shaft decreases. Therefore, in the apparatus including the condition that the execution condition is that the execution of the fuel injection by the basic injection control is temporarily stopped as in the above apparatus, the execution opportunity of the auxiliary injection control is also limited. According to the above-described device, it is possible to suppress the occurrence of misfire caused by replenishment of low cetane number fuel in a device in which the execution opportunity of such auxiliary injection control is limited.

In a preferred aspect, fuel injection is performed in a predetermined amount by the auxiliary injection control, an index value of the output torque of the internal combustion engine generated along with the execution of the fuel injection is detected, and the detected index value is used as the first index value. Store as an index value.

1 is a schematic diagram illustrating a schematic configuration of a control device for an internal combustion engine according to an embodiment of the present invention. Sectional drawing which shows the cross-section of a fuel injection valve. The time chart which shows the relationship between transition of fuel pressure and the detection time waveform of a fuel injection rate. The flowchart which shows the execution procedure of a correction process. The time chart which shows an example of the relationship between a detection time waveform and a basic time waveform. The flowchart which shows the specific execution procedure of a 1st index value detection process. Explanatory drawing explaining the calculation method of rotation fluctuation amount. The flowchart which shows the execution procedure of a 2nd index value calculation process. 6 is a schematic diagram showing a map structure of a calculation map used for calculating a second index value. The flowchart which shows the execution procedure of a cetane number area | region specific process. The timing chart which shows an example of the execution aspect of a 2nd index value calculation process and a cetane number area | region specific process.

Hereinafter, a control device for an internal combustion engine according to an embodiment of the present invention will be described.

As shown in FIG. 1, the vehicle 10 is equipped with an internal combustion engine 11 as a drive source. A crankshaft 12 of the internal combustion engine 11 is connected to wheels 15 via a clutch mechanism 13 and a manual transmission 14. In the vehicle 10, when a clutch operating member (for example, a clutch pedal) is operated by an occupant, the clutch mechanism 13 is in an operating state in which the connection between the crankshaft 12 and the manual transmission 14 is released.

An intake passage 17 is connected to the cylinder 16 of the internal combustion engine 11. Air is sucked into the cylinder 16 of the internal combustion engine 11 through the intake passage 17. As the internal combustion engine 11, one having a plurality (four [# 1 to # 4] in the present embodiment) of cylinders 16 is employed. A direct injection type fuel injection valve 20 that directly injects fuel into the cylinder 16 is attached to the internal combustion engine 11 for each cylinder 16. 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 16 of the internal combustion engine 11. In the internal combustion engine 11, the piston 18 is pushed down by the energy generated by the combustion of fuel in the cylinder 16, and the crankshaft 12 is forcibly rotated. Combustion gas burned in the cylinder 16 of the internal combustion engine 11 is discharged as an exhaust gas into an exhaust passage 19 of the internal combustion engine 11.

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. In the present embodiment, 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.

Hereinafter, the internal structure of the fuel injection valve 20 will be described.

As shown in FIG. 2, 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). Inside the housing 21 is provided 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 is formed with a plurality of injection holes 23 that communicate 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.

The fuel injection valve 20 employs an electrically driven type, and a piezoelectric actuator 29 in which a plurality of piezoelectric elements (for example, piezo elements) that expand and contract by input of a drive signal is provided in the housing 21. It has been. 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.

In this fuel injection valve 20, when a valve closing signal is input to the piezoelectric actuator 29, the piezoelectric actuator 29 contracts and the valve body 29 a moves, and the communication path 28 and the pressure chamber 26 are in communication with each other. The communication between the return passage 35 and the pressure chamber 26 is cut off. Thereby, the nozzle chamber 25 and the pressure chamber 26 are communicated with each other in a state where the discharge of the fuel in the pressure chamber 26 to the return passage 35 (fuel tank 32) is prohibited. Therefore, the pressure difference between the nozzle chamber 25 and the pressure chamber 26 becomes very small, and the needle valve 22 moves to a position where the injection hole 23 is closed by the urging force of the spring 24. At this time, the fuel injection valve 20 does not inject fuel. State (valve closed).

On the other hand, when a valve opening signal is input to the piezoelectric actuator 29, 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. As a result, 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. As a result, 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. Apart from the hole 23, the fuel injection valve 20 is in a state in which fuel is injected (opened state) at this time.

The fuel injection valve 20 is integrally attached with a pressure sensor 41 that outputs a signal corresponding to the fuel pressure PQ inside the introduction passage 27. 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. One pressure sensor 41 is provided for each fuel injection valve 20, that is, for each cylinder 16 of the internal combustion engine 11.

As shown in FIG. 1, the internal combustion engine 11 is provided with various sensors as peripheral devices for detecting an operation state. As these sensors, in addition to the pressure sensor 41, for example, the crank sensor 42 for detecting the rotational phase and rotational speed (engine rotational speed NE) of the crankshaft 12, and the operation amount of an accelerator operating member (for example, an accelerator pedal). An accelerator sensor 43 for detecting (accelerator operation amount ACC) is provided. Further, a vehicle speed sensor 44 for detecting the traveling speed of the vehicle 10, a clutch switch 45 for detecting whether or not the clutch operating member is operated, and the amount of fuel stored in the fuel tank 32 (the amount of stored fuel) A stockpiling amount sensor 46 for detecting SP) is provided. In addition, an operation switch 47 that is turned on when the operation of the internal combustion engine 11 is started and turned off when the operation is stopped is also provided.

Further, as a peripheral device of the internal combustion engine 11, for example, an electronic control unit 40 configured with a microcomputer is also provided. The electronic control unit 40 functions as a storage unit, a first control unit, and a second control unit. The electronic control unit 40 takes in output signals from various sensors and performs various calculations based on the output signals. Various controls related to the operation of the internal combustion engine 11 such as drive control (fuel injection control) of the injection valve 20 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 operation of the internal combustion engine 11 is calculated based on the accelerator operation amount ACC, the engine speed NE, and the like. 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. Thereby, an amount of fuel commensurate with the operation state of the internal combustion engine 11 at that time is injected from each fuel injection valve 20 and supplied into each cylinder 16 of the internal combustion engine 11. In the present embodiment, the drive control of each fuel injection valve 20 based on the required injection timing Tst and the required injection time Ttm corresponds to the basic injection control.

In the fuel injection control of the present embodiment, the engine rotational speed NE is set to a predetermined value during the deceleration of the traveling speed of the vehicle 10 and the engine rotational speed NE by releasing the operation of the accelerator operation member (accelerator operation amount ACC = “0”). When the speed is within the speed range, control (so-called fuel cut control) for temporarily stopping fuel injection for operation of the internal combustion engine 11 is executed.

Further, in the fuel injection control of the present embodiment, there are three areas: a low cetane number area (low cetane number area), a medium area (medium cetane number area), and a high area (high cetane number area). While being set, the fuel injection control is executed in a different execution mode for each region. For example, the required injection timing Tst is set to the advance timing for the region with the lower cetane number. Specifically, for each of the three cetane number regions, the relationship between the engine operating state determined by the required injection amount TAU and the engine speed NE and the required injection timing Tst corresponding to the cetane number region is the result of various experiments and simulations. And the same relationship is stored in the electronic control unit 40 as a calculation map (ML, MM, MH). Then, based on the required injection amount TAU and the engine speed NE at that time, the calculation map ML is used for the low cetane number region, the calculation map MM is used for the medium cetane number region, and the calculation is performed for the high cetane number region. The required injection timing Tst is calculated from each map MH.

When the fuel injection from the fuel injection valve 20 is executed in this way, an error may occur in the execution timing and the injection amount due to the initial individual difference of the fuel injection valve 20 and the change over time. Such an error is undesirable because it changes the output torque of the internal combustion engine 11. Therefore, in the present embodiment, in order to properly execute the fuel injection from each fuel injection valve 20 in accordance with the operation state of the internal combustion engine 11, the fuel is based on the fuel pressure PQ detected by the pressure sensor 41. A correction process for forming the injection rate detection time waveform and correcting the required injection timing Tst and the required injection time Ttm based on the detection time waveform is executed. This correction process is executed separately for each cylinder 16 of the internal combustion engine 11.

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, by monitoring the fluctuation waveform of the fuel pressure inside the fuel injection valve 20 at the time of fuel injection execution, the actual operation characteristics of the fuel injection valve 20 (for example, the actual fuel injection amount and the valve opening operation are started). And when the valve closing operation is started). Therefore, by correcting the required injection timing Tst and the required injection time Ttm based on the actual operating characteristics of the fuel injection valve 20, the fuel injection timing and the fuel injection amount can be accurately adjusted in accordance with the operating state of the internal combustion engine 11. Can be set.

Hereinafter, such correction processing will be described in detail.

Here, first, a procedure for forming a fuel pressure fluctuation mode (in the present embodiment, a fuel injection rate detection time waveform) at the time of fuel injection will be described.

FIG. 3 shows the relationship between the transition of the fuel pressure PQ and the detection time waveform of the fuel injection rate.

As shown in FIG. 3, in the present embodiment, 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).

First, 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.

Next, a value obtained by subtracting the predetermined pressure P1 from the reference pressure Pbs is calculated as the operating pressure Pac (= Pbse−P1). 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.

Thereafter, a first-order differential value d (PQ) / dt is calculated according to the time of the fuel pressure PQ in a period in which the fuel pressure PQ drops immediately after the start of fuel injection. Then, the tangent L1 of the time waveform of the fuel pressure PQ at the point where the first-order differential value becomes the minimum, that is, the point where the downward slope of the fuel pressure PQ becomes the largest is obtained, and the intersection of the tangent L1 and the operating pressure Pac is obtained. A is calculated. The timing corresponding to the point AA where the intersection A is returned to the past timing by the following 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 pressure sensor 41. This is a delay caused by the above.

Also, 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. Then, the tangent L2 of the time waveform of the fuel pressure PQ at the point where the first-order differential value becomes the maximum, that is, the point where the upward slope of the fuel pressure PQ becomes the largest, is obtained, and the intersection of the tangent L2 and the operating pressure Pac B 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.

Furthermore, the intersection C between the tangent line L1 and the tangent line L2 is calculated, and the difference (virtual pressure drop ΔP [= Pac−PQ]) between the fuel pressure PQ and the operating pressure Pac at the intersection C is obtained. Further, a value obtained by multiplying the virtual pressure drop ΔP by a gain G1 set based on the required injection amount TAU is calculated as a virtual maximum fuel injection rate VRt (= ΔP × G1). Further, a value obtained by multiplying the virtual maximum fuel injection rate VRt by a gain G2 set based on the required injection amount TAU is calculated as the maximum injection rate Rt (= VRt × G2).

Thereafter, 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.

Further, 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.

Further, 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.

Next, with reference to FIGS. 4 and 5, a processing procedure of correcting (controlling) various control target values for fuel injection control based on such a detection time waveform will be described in detail.

FIG. 4 is a flowchart showing a specific processing procedure of the correction processing. The series of processes shown in this flowchart conceptually shows the execution procedure of the correction process, and the actual process is executed by the electronic control unit 40 as an interrupt process at predetermined intervals. FIG. 5 shows an example of the relationship between the detection time waveform and the following basic time waveform.

As shown in FIG. 4, in this correction process, first, as described above, a detection time waveform at the time of execution of fuel injection is formed based on the fuel pressure PQ (step S101). Further, based on the operating state of the internal combustion engine 11 such as the accelerator operation amount ACC and the engine speed NE, a basic value (basic time waveform) for the time waveform of the fuel injection rate at the time of execution of fuel injection is set (step). S102). In the present embodiment, the relationship between the operating state of the internal combustion engine 11 and the basic time waveform suitable for the operating 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 operating state of the internal combustion engine 11 at that time.

As shown in FIG. 5, 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.

Then, the basic time waveform and the detection time waveform (solid line) are compared, and a correction term for correcting the control target value (the required injection timing Tst) of the fuel injection start timing based on the comparison result. K1 and a correction term K2 for correcting the control target value (required injection time Ttm) of the execution time of the same fuel injection are respectively calculated. Specifically, a difference ΔTos (= Tosb−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, and the difference ΔTos is stored as the correction term K1. (Step S103 in FIG. 4). Further, a difference ΔTcs (= Tcsb−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, and the difference ΔTcs is corrected by the correction term K2. (Step S104 in FIG. 4).

After the correction terms K1 and K2 are calculated in this way, this process is temporarily terminated.

When executing the fuel injection control, 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. By calculating the required injection timing Tst in this way, the deviation 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 can be suppressed to be small. The start timing of injection is accurately set according to the operating state of the internal combustion engine 11.

Further, a value obtained by correcting the required injection time Ttm by the correction term K2 (in this embodiment, a value obtained by adding the correction term K2 to the required injection time Ttm) is calculated as the final required injection time Ttm. By calculating the required injection time Ttm in this way, the deviation between the injection rate decrease start timing Tcsb in the basic time waveform and the injection rate decrease start timing Tcs in the detection time waveform can be suppressed to be small. The timing at which the fuel injection rate starts to decrease in the fuel injection is set with high accuracy in accordance with the operating state of the internal combustion engine 11.

As described above, in the present embodiment, the required injection timing is based on the difference between the actual operating characteristic (specifically, the detection time waveform) of the fuel injection valve 20 and the predetermined basic operating characteristic (specifically, the basic time waveform). Since the Tst and the required injection time Ttm are corrected, the 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. Therefore, the injection timing and the injection amount in the fuel injection from each fuel injection valve 20 are set appropriately so as to match the operating state of the internal combustion engine 11.

In the present embodiment, control (first index value detection process) for detecting the cetane number index value of the fuel to be used for combustion in the internal combustion engine 11 is executed. Hereinafter, an outline of the first index value detection process will be described.

In the first index value detection process, an execution condition including a condition that the above-described fuel cut control is being executed ([Condition 1] described later) is set. Then, when this execution condition is satisfied, fuel injection to the internal combustion engine 11 at a predetermined small predetermined amount FQ (for example, several cubic millimeters) is executed, and the internal combustion generated along with the execution of the fuel injection An index value of the output torque of the engine 11 (rotational fluctuation amount ΣΔNE described later) is detected as a fuel cetane number index value. As the rotational fluctuation amount ΣΔNE, a larger value is detected as a larger output torque is generated in the internal combustion engine 11.

The higher the cetane number of the fuel supplied to the internal combustion engine 11, the easier it is to ignite the fuel, and the less unburned fuel of the fuel decreases, so the engine torque generated as the fuel burns increases. In the estimation control of the present embodiment, the cetane number index value of the fuel is detected based on the relationship between the cetane number of the fuel and the output torque of the internal combustion engine 11.

Hereinafter, the execution procedure of the first index value detection process will be described in detail.

FIG. 6 is a flowchart showing a specific execution procedure of the first index value detection process. The series of processes shown in this flowchart conceptually shows the execution procedure of the first index value detection process, and the actual process is executed by the electronic control unit 40 as an interrupt process at predetermined intervals. .

As shown in FIG. 6, in this process, it is first determined whether or not an execution condition is satisfied (step S201). Here, it is determined that the execution condition is satisfied when all of the following [Condition 1] to [Condition 3] are satisfied.
[Condition 1] The fuel cut control is executed.
[Condition 2] The clutch mechanism 13 is in an operating state in which the connection between the crankshaft 12 and the manual transmission 14 is released. Specifically, the clutch operating member is operated.
[Condition 3] The correction process is properly executed. Specifically, each correction term K1, K2 calculated in the correction process is neither an upper limit nor a lower limit.

If the above execution condition is not satisfied (step S201: NO), this process is temporarily terminated without executing the following process, that is, the process of detecting the cetane number index value of the fuel.

Thereafter, when this process is repeatedly executed and the above execution condition is satisfied (step S201: YES), execution of the process for detecting the cetane number index value of the fuel is started.

Specifically, first, a predetermined control target value for fuel injection timing (target injection timing TQst) and a control target value for fuel injection time (target injection time TQtm) are obtained by the correction processing described above with reference to FIGS. Correction is performed by the calculated correction terms K1 and K2 (step S202 in FIG. 6). Specifically, a value obtained by adding the correction term K1 to the target injection timing TQst is set as a new target injection timing TQst, and a value obtained by adding the correction term K2 to the target injection time TQtm is set as a new target injection time TQtm. The

Then, drive control of the fuel injection valve 20 based on the target injection timing TQst and the target injection time TQtm is executed, and fuel injection from the fuel injection valve 20 is executed (step S203). Through such drive control of the fuel injection valve 20, a predetermined amount FQ of fuel is injected from the fuel injection valve 20 at a timing at which variations in the rotational fluctuation amount ΣΔNE are suppressed. In the present embodiment, the fuel injection in the process of step S203 is a predetermined one of the plurality of fuel injection valves 20 (in this embodiment, the fuel injection valve 20 attached to the cylinder 16 [# 1]). It is executed using Similarly, the correction terms K1 and K2 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 cylinders 16 [# 1]). The value calculated corresponding to is used. In the present embodiment, the drive control of the fuel injection valve 20 based on the target injection timing TQst and the target injection time TQtm by the process of step S203 corresponds to the auxiliary injection control.

Thereafter, after the rotational fluctuation amount ΣΔNE is detected and stored as an index value of the output torque of the internal combustion engine 11 generated by the fuel injection at the predetermined amount FQ (step S204), the present process is temporarily terminated. Specifically, the rotation fluctuation amount ΣΔNE is detected as follows. As shown in FIG. 7, in the apparatus according to the present embodiment, the engine rotational speed NE is detected every predetermined time, and at each detection, the engine rotational speed NE and the previous engine rotational speed NE are detected several times (in the present embodiment). The difference ΔNE (= NE−NEi) from the engine speed NEi detected three times before) is calculated. Then, an integrated value (a value corresponding to the area of the hatched portion in FIG. 7) for the change in the difference ΔNE accompanying the execution of the fuel injection is calculated, and this integrated value is calculated as the rotational fluctuation amount. Stored as ΣΔNE. Note that the transition of the engine speed NE and the difference ΔNE shown in FIG. 7 are slightly different from the actual transition because they are shown in a simplified manner to facilitate understanding of the calculation method of the rotational fluctuation amount ΣΔNE.

In the present embodiment, basically, the low cetane number region, the medium cetane number region, or the high cetane number region is specified based on the rotational fluctuation amount ΣΔNE detected through the first index value detection process. At the same time, the specified area is stored in the electronic control unit 40. Specifically, when the rotational fluctuation amount ΣΔNE is less than the predetermined value PL (ΣΔNE <PL), it is determined that the region is in the low cetane number region, and when the rotational fluctuation amount ΣΔNE is less than the predetermined value PH (PL ≦ ΣΔNE <PH). Is determined to be in the medium cetane number region, and if it is equal to or greater than the predetermined value PH (ΣΔNE ≧ PH), it is determined to be in the high cetane number region. Then, the fuel injection control is executed in an execution manner commensurate with the cetane number region thus specified.

Here, in the present embodiment, since fuel injection for detecting the cetane number index value of fuel is executed only when the above execution condition is satisfied, fuel supply is performed and the fuel in the fuel tank 32 is Even if the cetane number of the fuel changes, the state where the estimation of the cetane number of the fuel is not executed is continued unless the execution condition is satisfied.

In this case, if fuel having a relatively low cetane number is replenished in a situation where it has been determined that it is in the high cetane number region before refueling, the cetane number of the fuel in the fuel tank 32 becomes low and the internal combustion engine 11 In spite of the low cetane number of the fuel supplied to the fuel, the fuel injection control is executed in an execution mode suitable for the high cetane number region. In this case, not only the combustion state of the fuel in the cylinder 16 of the internal combustion engine 11 is deteriorated but also misfire is caused in some cases.

In the present embodiment, since [condition 1] is included in the execution conditions, the detection of the cetane number index value of the fuel is performed when the fuel cut control is executed, that is, the traveling speed of the vehicle 10 and the engine rotational speed NE are decelerated. It is executed only under limited circumstances such as when the engine speed NE is within a predetermined speed range. Therefore, for example, when the internal combustion engine 11 is started after being refueled and left in an idle operation state, or when high-speed traveling continues immediately after refueling on a highway or the like, the execution condition is In some cases, it does not hold for a long time, and the degree of influence tends to increase when misfire occurs due to replenishment of low cetane fuel.

In the present embodiment, based on such circumstances, when the fuel tank 32 is refueled, the fuel having the lowest cetane number among the fuels that may be replenished to the fuel tank 32 is replenished. In this case, the cetane number index value (specifically, the rotational fluctuation amount ΣΔNE) of the fuel in the fuel tank 32 after refueling is calculated as the second index value VS. Then, instead of executing the process of specifying the cetane number region using the rotation fluctuation amount ΣΔNE stored in the electronic control unit 40 as the specific parameter, the second index value VS is executed as the specific parameter. Yes. The fuel having the lowest cetane number among the fuels that may be replenished to the fuel tank 32 described above is determined in consideration of all the fuels circulating in the region where the vehicle 10 is supposed to travel. Or may be determined in consideration of all fuels distributed in all regions.

As a result, even if the cetane number of the fuel in the fuel tank 32 is lowered by refueling, the rotational fluctuation amount ΣΔNE calculated and stored before refueling, that is, a relatively high cetane number is shown. The situation where the value is used for fuel injection control is suppressed.

Moreover, the second index value VS, that is, the cetane number index value of the fuel in the fuel tank 32 after refueling when the fuel having the lowest cetane number among the fuels that may be replenished to the fuel tank 32 is replenished. Based on this, fuel injection control is executed. Therefore, when the fuel tank 32 is refueled, a fuel having a cetane number equal to or lower than the cetane number of the fuel actually supplied to the internal combustion engine 11 is supplied to the internal combustion engine 11. As a result, the fuel injection control can be executed. In this case, since the combustion state of the fuel in the internal combustion engine 11 may be better than the assumed combustion state, it does not worsen, so that the misfire occurrence accompanying the deterioration of the combustion state is suitably suppressed. Be able to. Therefore, even if the fuel tank 32 is replenished with low cetane number fuel, the occurrence of misfire due to the refueling can be suppressed.

Hereinafter, a process for calculating the second index value VS and a process for executing the fuel injection control based on the second index value VS will be described in detail.

Here, first, a process for calculating the second index value VS (second index value calculation process) will be described.

FIG. 8 shows an execution procedure of the second index value calculation process. The series of processes shown in the flowchart of FIG. 6 is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.

As shown in FIG. 8, in this process, it is first determined whether or not the refueling flag is turned on (step S301). The refueling flag is a flag that is turned on when it is determined that the fuel tank 32 has been refueled, and that is turned off when the calculation of the second index value VS is completed. The fuel supply to the fuel tank 32 is determined as follows. In the present embodiment, the stored fuel amount SP detected by the storage amount sensor 46 when the operation switch 47 is turned off is the amount of fuel stored in the fuel tank 32 at the start of fuel replenishment (the reserve amount before replenishment). V1) is stored. Further, the stored fuel amount SP detected by the stored amount sensor 46 when the operation switch 47 is turned on is used as the amount of fuel stored in the fuel tank 32 after refueling (replenished stock amount VP). Then, when the operation switch 47 is turned on, the amount of fuel replenished to the fuel tank 32 (fuel replenishment amount V2 [= VP−V1]) and the stock amount change from the pre-replenishment stock amount V1 and the post-supplement stock amount VP The rate RP (= VP / V1) is calculated respectively. When the fuel supply amount V2 is greater than or equal to a predetermined amount, or when the stockpiling amount change rate RP is greater than or equal to a predetermined value, it is determined that fuel supply has been performed.

If it is determined that the refueling flag is turned on (step S301: YES), a process for calculating the second index value VS is executed (step S302). In this process, the rotational fluctuation amount ΣΔNE stored when the operation switch 47 is turned on is used as the index value S1 of the cetane number of the fuel stored in the fuel tank 32 before refueling. The index value S1, the amount of fuel stored in the fuel tank 32 at the start of fuel replenishment (pre-replenishment storage amount V1), the amount of fuel replenished to the fuel tank 32 (fuel replenishment amount V2), A value satisfying the following relational expression is calculated as the second index value VS on the basis of the predetermined cetane number index value S2 determined.

VS = (V1 × S1 + V2 × S2) / (V1 + V2)

Specifically, as shown in FIG. 9, a plurality of pre-replenishment reserve amounts V1, fuel replenishment amounts V2, and second index values VS are determined for each index value S1 and stored in the electronic control unit 40. The second index value VS is calculated from these relationships (calculation map). The predetermined cetane number index value S2 is the index value of the lowest cetane number among the cetane numbers of fuel that may be supplied to the fuel tank 32 (specifically, a value corresponding to the rotational fluctuation amount ΣΔNE). is there.

Then, when the second index value VS is calculated in this way (step S302), the refueling flag is turned off (step S303), and then this process is temporarily terminated. Thereafter, the second index value VS is not calculated unless the fuel supply to the fuel tank 32 is performed and the refueling flag is turned on (step S301: NO).

By calculating the second index value VS in this way, the fuel tank 32 in the fuel tank 32 after refueling under the assumption that the cetane number of the fuel replenished to the fuel tank 32 is a predetermined value. The cetane number of the fuel can be estimated. Therefore, by setting an appropriate value as the predetermined value, a value that serves as a lower limit index of the change range of the cetane number of the fuel in the fuel tank 32 after refueling can be calculated as the second index value VS. . In the present embodiment, as the predetermined cetane number index value S2, the index value of the lowest cetane number among the cetane numbers of fuels that may be supplied to the fuel tank 32 is employed. Therefore, the second index value VS corresponds to the cetane number of the fuel in the fuel tank 32 after refueling when the fuel having the lowest cetane number among the fuels that may be replenished to the fuel tank 32 is replenished. The value to be calculated can be calculated. Therefore, it is possible to grasp how low the cetane number of the fuel in the fuel tank 32 after refueling may be based on the second index value VS.

Next, processing for specifying a cetane number region used for fuel injection control (cetane number region specifying process) will be described.

FIG. 10 shows an execution procedure of the cetane number area specifying process. The series of processes shown in the flowchart of FIG. 6 is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.

As shown in FIG. 10, in this process, it is first determined whether or not the post-refueling update completion flag is turned off (step S401). The post-refueling update completion flag is turned off when it is determined that the fuel tank 32 has been refueled, and turned on when the execution condition is satisfied and the rotational fluctuation amount ΣΔNE is newly stored. The flag to be manipulated.

When the post-refueling update completion flag is turned off (step S401: YES), the rotational fluctuation amount ΣΔNE is still updated because the execution condition is not satisfied after the fuel is supplied to the fuel tank 32. As a result, the cetane number region is specified based on the second index value VS, and the specified region is stored (step S402).

Specifically, in this process, when the second index value VS is less than the predetermined value PL (VS <PL), it is determined that the region is a low cetane number region, and when the second index value VS is greater than or equal to the predetermined value PL and less than the predetermined value PH (PL If it is ≦ VS <PH, it is determined to be in the medium cetane number region, and if it is equal to or greater than the predetermined value PH (VS ≧ PH), it is determined to be in the high cetane number region. In the present embodiment, the fuel injection control is executed in an execution mode commensurate with the cetane number region thus specified.

On the other hand, when the post-refueling update completion flag is turned on (step S401: NO), the rotational fluctuation amount ΣΔNE is updated and stored in the electronic control unit 40 after the fuel tank 32 is refueled. A cetane number region is specified based on the rotational fluctuation amount ΣΔNE, and the specified region is stored (step S403).

Specifically, in this process, when the rotational fluctuation amount ΣΔNE is less than the predetermined value PL (ΣΔNE <PL), it is determined that the region is in the low cetane number region, and when the rotational fluctuation amount ΣΔNE is less than the predetermined value PH (PL ≦ ΣΔNE). <PH) is determined to be in the medium cetane number region, and if it is greater than or equal to the predetermined value PH (ΣΔNE ≧ PH), it is determined to be in the high cetane number region. In the present embodiment, the fuel injection control is executed in an execution mode commensurate with the cetane number region thus specified.

As described above, in the present embodiment, after the fuel supply to the fuel tank 32 is performed, when the execution condition is satisfied and the rotational fluctuation amount ΣΔNE is updated, the fuel injection control based on the second index value VS is performed. Execution is stopped and execution of fuel injection control based on the rotational fluctuation amount ΣΔNE is started. As a result, even if the fuel tank 32 is refueled and the cetane number of the fuel stored in the fuel tank 32 is changed, the rotational fluctuation amount ΣΔNE is updated after the fuel is replenished. , The fuel injection control is executed in accordance with the rotational fluctuation amount ΣΔNE, that is, in accordance with the actual fuel cetane number index value.

Hereinafter, the effect of executing the second index value calculation process and the cetane number region specifying process will be described with reference to the timing chart shown in FIG.

In the example shown in FIG. 11, fuel having a relatively high cetane number is stored in the fuel tank 32 before the time t1. At this time, the post-refueling update completion flag is turned on. Therefore, the fuel injection control is executed based on the rotational fluctuation amount ΣΔNE (lines L5 and L6 in the figure) stored in the electronic control unit 40, that is, a value indicating a high cetane number. Specifically, the high cetane number region is specified based on the rotational fluctuation amount ΣΔNE, and the fuel injection control is executed in an execution mode commensurate with the high cetane number region. In FIG. 11, a line L5 indicates the rotational fluctuation amount ΣΔNE stored in the electronic control unit 40, and a line L6 indicates a value used for specifying the cetane number region.

At time t1, the operation switch 47 is turned off to stop the operation of the internal combustion engine 11, and the fuel tank 32 is refueled while the operation is stopped (time t1 to t2). At this time, the fuel tank 32 is replenished with fuel having a relatively low cetane number. In this example, the average value of the cetane number of the fuel in the fuel tank 32 becomes the medium cetane number region by refueling.

At subsequent time t2, the operation switch 47 is turned on, and the operation of the internal combustion engine 11 is started. Since the fuel tank 32 has been refueled while the operation of the internal combustion engine 11 is stopped, the post-refueling update completion flag is turned off. Therefore, at this time, the second index value VS (line L7 in the figure) is calculated, and execution of fuel injection control based on the second index value VS is started.

The rotational fluctuation amount ΣΔNE stored in the electronic control unit 40 at this time is a value corresponding to the cetane number of the fuel stored in the fuel tank 32 before refueling. Therefore, when the fuel injection control is executed based on the rotational fluctuation amount ΣΔNE, the fuel cetane number in the fuel tank 32 is lowered by refueling, but the relatively high value stored before refueling is stored. The fuel injection control is executed based on the cetane number index value (rotational fluctuation amount ΣΔNE indicated by line L6 in the figure). Specifically, although the cetane number of the fuel in the fuel tank 32 is in the medium cetane number region, the fuel injection control is performed in an execution mode commensurate with the high cetane number region based on the rotational fluctuation amount ΣΔNE at this time. Will be executed.

On the other hand, in the apparatus of the present embodiment, the second index value VS (lines L5 and L7 in the figure), that is, the fuel having the lowest cetane number among the fuels that may be supplied to the fuel tank 32 is obtained. The fuel injection control is executed based on the cetane number index value of the fuel in the fuel tank 32 after the fuel is replenished. Specifically, the low cetane number region is specified based on the second index value VS, and the fuel injection control is executed in an execution manner commensurate with the low cetane number region.

Therefore, when the cetane number of the fuel in the fuel tank 32 is lowered by refueling, fuel injection control is executed based on the relatively high cetane number index value (rotational fluctuation amount ΣΔNE) stored before refueling. It is avoided that the situation becomes. In this example, the fuel injection control is executed in an execution mode corresponding to the low cetane number region on the lower cetane number side as compared to the medium cetane number region to which the actual cetane number of the fuel in the fuel tank 32 belongs. In the fuel injection control of the present embodiment, as an execution mode corresponding to each cetane number region, the combustion state of the fuel in the cylinder 16 of the internal combustion engine 11 tends to be better as the cetane number region on the lower cetane number side. An execution mode is set. Therefore, in this case, since the combustion state of the fuel in the internal combustion engine 11 may be better than the assumed combustion state, it does not worsen. It becomes suppressed suitably. Therefore, even if the fuel tank 32 is supplied with a low cetane fuel, the occurrence of misfire due to the fuel supply can be suppressed.

If the fuel having the lowest cetane number described above is actually supplied to the fuel tank 32, a value equivalent to the cetane number index value of the fuel in the fuel tank 32 after refueling is the second index value VS. Is calculated as Therefore, by executing the fuel injection control based on the second index value VS, the fuel injection control is executed in an execution mode corresponding to the same region as the cetane number region to which the actual cetane number of the fuel in the fuel tank 32 belongs. Thus, the occurrence of misfire caused by refueling is suppressed.

At the subsequent time t3, the execution condition is satisfied, and the rotational fluctuation amount ΣΔNE is detected and updated through the first index value detection process. Accordingly, the post-refueling update completion flag is turned on. Therefore, at this time, as indicated by a line L5 in the drawing, the execution of the fuel injection control based on the second index value VS is stopped, and the execution of the fuel injection control based on the rotational fluctuation amount ΣΔNE is started. Specifically, the execution mode of the fuel injection control is switched from the execution mode suitable for the low cetane number region to which the second index value VS belongs to the execution mode suitable for the medium cetane number region to which the rotational fluctuation amount ΣΔNE belongs. Thereafter, the fuel injection control is executed in accordance with the rotational fluctuation amount ΣΔNE, in other words, in accordance with the actual cetane number of the fuel.

As described above, according to the present embodiment, the following effects can be obtained.

(1) When fuel is supplied to the fuel tank 32, the cetane number index value S1, the reserve amount V1 before supply, and the fuel supply amount V2 of the fuel stored in the fuel tank 32 before supplying fuel are obtained. Based on this, the second index value VS of the cetane number of the fuel is calculated, and the fuel injection control is executed based on the second index value VS. Therefore, even when the fuel tank 32 is replenished with a low cetane fuel, the occurrence of misfire due to the refueling can be suppressed.

(2) The second index value VS is calculated based on the index value S1, the pre-replenishment reserve amount V1, the fuel replenishment amount V2, and the predetermined cetane number index value S2, [VS = (V1 × S1 + V2 × S2) / (V1 + V2)] is calculated.

(3) As the predetermined cetane number index value S2, the index value of the lowest cetane number among the cetane numbers of fuels that may be supplied to the fuel tank 32 is adopted. Therefore, the second index value VS corresponds to the cetane number of the fuel in the fuel tank 32 after refueling when the fuel having the lowest cetane number among the fuels that may be replenished to the fuel tank 32 is replenished. The value to be calculated can be calculated. Therefore, it is possible to grasp how low the cetane number of the fuel in the fuel tank 32 after refueling may be based on the second index value VS.

(4) When the execution condition is satisfied and the rotational fluctuation amount ΣΔNE is updated after the fuel supply to the fuel tank 32 is performed, the execution of the fuel injection control based on the second index value VS is stopped and the rotation is performed. The fuel injection control based on the fluctuation amount ΣΔNE is started. Therefore, even when the fuel is replenished and the cetane number of the fuel stored in the fuel tank 32 changes, after the rotation fluctuation amount ΣΔNE is updated thereafter, the rotation fluctuation amount ΣΔNE, That is, the fuel injection control can be executed in accordance with the actual fuel cetane number index value.

(5) Since the rotational fluctuation amount ΣΔNE is detected only under a limited situation such as when fuel cut control is executed, the degree of influence when a misfire occurs due to the replenishment of the low cetane fuel is large. In a device that is likely to become misfired, the occurrence of misfire due to replenishment of low cetane number fuel can be suppressed.

Note that the above embodiment may be modified as follows.

The cetane number index value S2 is not limited to the index value of the lowest cetane number among the cetane numbers of fuels that may be replenished to the fuel tank 32, and the cetane number index value S2 is slightly higher than the lowest cetane number. It may be an index value. In short, if the cetane number region specified based on the second index value VS is a value that does not become a higher cetane number region than the cetane number region to which the cetane number of the fuel in the fuel tank 32 belongs, the same value is used as the cetane number index. It can be the value S2.

The second index value VS may be calculated from an arithmetic expression instead of calculating from the arithmetic map. In the same configuration, the relational expression [VS = (V1 × S1 + V2 × S2) / (V1 + V2)] is stored in the electronic control unit 40 in advance, and the index value S1, the reserve amount V1 before replenishment, the fuel replenishment amount V2, The second index value VS may be calculated from the relational expression based on the predetermined cetane number index value S2.

If the errors in the fuel injection timing and the fuel injection amount due to the initial individual differences and changes with time of the fuel injection valve 20 can be appropriately suppressed, the target injection timing TQst and the target injection time TQtm are corrected by the correction terms K1, K2. May be omitted (step S202 in FIG. 6).

The control device according to the above embodiment is a device that determines which of the two regions divided by the fuel cetane number index value (rotational fluctuation amount ΣΔNE), or any of the four or more regions. The present invention can also be applied to a device that determines whether the region is the region after the configuration is appropriately changed.

As control for changing the execution mode according to the cetane number region specified based on the rotational fluctuation amount ΣΔNE or the second index value VS, instead of or in addition to adopting control for setting the required injection timing Tst Further, EGR control, pilot injection control, or the like may be employed. The point is that the combustion control related to the combustion of fuel in the internal combustion engine 11, in other words, the combustion control for adjusting the combustion state of the fuel in the internal combustion engine 11, is adopted as the control for changing the execution mode according to the cetane number region. be able to. In an apparatus that employs EGR control as such combustion control, the EGR control may be executed so that the EGR amount decreases as it is in the low cetane number region. Further, in an apparatus that employs pilot injection control as combustion control, pilot injection control may be executed so that the pilot injection amount increases, for example, when the region is on the low cetane number side.

The control device according to the above embodiment performs the fuel injection control execution mode according to the rotational fluctuation amount ΣΔNE itself without specifying the cetane number region based on the rotational fluctuation amount ΣΔNE stored in the electronic control unit 40. The present invention can also be applied to the apparatus to be determined after the configuration is appropriately changed. In such an apparatus, when fuel is replenished to the fuel tank 32, the rotational fluctuation amount ΣΔNE, the pre-replenishment storage amount V1, and the fuel replenishment amount V2 that are detected and stored in the electronic control unit 40 before refueling. The second index value VS may be calculated based on the above, and the execution mode of the fuel injection control may be determined according to the second index value VS.

The control device according to the above embodiment estimates the cetane number of the fuel itself based on the rotational fluctuation amount ΣΔNE stored in the electronic control unit 40 and performs the fuel injection control in an execution mode corresponding to the estimated cetane number. The present invention can also be applied to a device to be executed after the configuration is appropriately changed. In such a device, when the fuel tank 32 is refueled, the estimated cetane number, the pre-replenishment reserve amount V1, and the fuel replenishment amount V2 that are estimated before refueling and stored in the electronic control unit 40 are stored. The second index value of the cetane number of the fuel may be calculated based on the above, and the fuel injection control may be executed based on the second index value.

A value other than the rotational fluctuation amount ΣΔNE may be calculated as an index value of the output torque of the internal combustion engine 11. For example, during the execution of the first index value detection process, the engine rotational speed NE at the time of execution of fuel injection and the engine rotational speed NE immediately before the execution of the fuel injection are detected and the difference between these speeds is calculated. Can be used as the index value.

The pressure sensor 41 is mounted in an appropriate manner so that the fuel pressure indicator in the fuel injection valve 20 (specifically, in the nozzle chamber 25), in other words, the fuel pressure that changes with the change in the fuel pressure is appropriately set. As long as it can be detected, the present invention is not limited to the mode of being directly attached to the fuel injection valve 20, but can be arbitrarily changed. Specifically, the pressure sensor may be attached to the branch passage 31 a or the common rail 34.

-Instead of the type of fuel injection valve 20 driven by the piezoelectric actuator 29, for example, a type of fuel injection valve driven by an electromagnetic actuator provided with a solenoid coil or the like may be employed.

The control device according to the above embodiment can be applied not only to the vehicle 10 on which the clutch mechanism 13 and the manual transmission 14 are mounted, but also to a vehicle on which a torque converter and an automatic transmission are mounted. In such a vehicle, for example, when [Condition 1] and [Condition 3] are satisfied, fuel injection for estimating the cetane number of fuel may be executed. In a vehicle in which a lockup clutch is incorporated as a torque converter, [Condition 4] that the lockup clutch is not engaged is newly set and the [Condition 4] is satisfied. The fuel injection for detecting the cetane number index value of the fuel may be executed on the condition that

The present invention is not limited to a device that performs fuel injection (auxiliary injection control) for estimating the cetane number on condition that the execution condition is satisfied, and the index value of the cetane number matches the actual cetane number after refueling Any device that takes time to reach a value can be applied. Examples of such a device include the following devices. That is, first, the pressure in the cylinder of the internal combustion engine (in-cylinder pressure) is detected by the in-cylinder pressure sensor during the execution of fuel injection for the operation of the internal combustion engine. Based on this in-cylinder pressure, the time when the fuel is actually ignited is calculated, and the ignition delay time is calculated based on the same period. Thereafter, an average value of the calculated ignition delay time is calculated, and a cetane number index value is calculated based on the average value.

The present invention is not limited to an internal combustion engine having four cylinders, but also to a single cylinder internal combustion engine, an internal combustion engine having two cylinders, an internal combustion engine having three cylinders, or an internal combustion engine having five or more cylinders. Can be applied.

DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Internal combustion engine, 12 ... Crankshaft, 13 ... Clutch mechanism, 14 ... Manual transmission, 15 ... Wheel, 16 ... Cylinder, 17 ... Intake passage, 18 ... Piston, 19 ... Exhaust passage, 20 ... Fuel Injection valve, 21 ... housing, 22 ... needle valve, 23 ... injection hole, 24 ... spring, 25 ... nozzle chamber, 26 ... pressure chamber, 27 ... introduction passage, 28 ... communication passage, 29 ... piezoelectric actuator, 29a ... valve body , 30 ... discharge passage, 31a ... branch passage, 31b ... supply passage, 32 ... fuel tank, 33 ... fuel pump, 34 ... common rail, 35 ... return passage, 40 ... electronic control unit, 41 ... pressure sensor, 42 ... crank sensor , 43 ... Accelerator sensor, 44 ... Vehicle speed sensor, 45 ... Clutch switch, 46 ... Reserve amount sensor, 47 ... Operation switch.

Claims

A cetane number index value of fuel supplied to the internal combustion engine is calculated, and a storage unit that stores the same value as a first index value, and combustion control related to fuel combustion is executed based on the first index value stored by the storage unit A control device for an internal combustion engine having a first control unit that
When fuel is supplied to the fuel tank, the amount of fuel stored in the fuel tank at the start of the fuel supply, the first index value stored at the start of the fuel supply, A second control unit that calculates a second index value of the cetane number of the fuel based on the amount of fuel replenished to the fuel tank, and executes the combustion control based on the second index value;
A control device for an internal combustion engine, comprising:
The control apparatus for an internal combustion engine according to claim 1,
The second control unit sets the amount of fuel stored in the fuel tank at the start of the fuel supply to “V1”, and stores the first index value stored at the start of the fuel supply as “S1”. When the amount of fuel replenished to the fuel tank is “V2”, the predetermined cetane number index value set in advance is “S2”, and the second index value is “VS”, the following relational expression:
VS = (V1 × S1 + V2 × S2) / (V1 + V2)
A control apparatus for an internal combustion engine, characterized in that a second index value VS that satisfies the above is calculated.
The control apparatus for an internal combustion engine according to claim 2,
The control apparatus for an internal combustion engine, wherein the predetermined cetane number index value S2 is an index value of the lowest cetane number among the cetane numbers of fuel that may be replenished to the fuel tank.
The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
When the first index value is newly stored by the storage unit after the fuel tank is refueled, the second control unit stops the execution of combustion control based on the second index value, The control apparatus for an internal combustion engine, wherein the first control unit starts execution of combustion control based on the first index value.
The control apparatus for an internal combustion engine according to any one of claims 1 to 4,
The storage unit is configured to perform fuel injection for detecting the cetane number index value of the fuel on condition that an execution condition is satisfied, separately from basic injection control in which fuel injection is performed in an amount corresponding to an operating state of the internal combustion engine. A control device for an internal combustion engine, wherein the auxiliary injection control is performed, and the cetane number index value obtained as a result of fuel injection by the auxiliary injection control is stored as the first index value.
The control apparatus for an internal combustion engine according to claim 5,
The control apparatus for an internal combustion engine, wherein the execution condition includes a condition that execution of fuel injection by the basic injection control is temporarily stopped.
The control apparatus for an internal combustion engine according to claim 5 or 6,
The storage unit performs fuel injection by a predetermined amount through the auxiliary injection control, detects an index value of the output torque of the internal combustion engine generated along with the execution of fuel injection, and uses the detected index value. A control device for an internal combustion engine, which is stored as the first index value.