JP2003314330A - Injection quantity control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel injection control accuracy by performing the injection quantity fluctuation restricting control between cylinders, not only in the FCCB correcting condition (idle stabilized condition) that command injection quantity (QFIN) and the common rail pressure (NPC) are low, but also other injection condition. <P>SOLUTION: In the case where a deviation between the Tq correction quantity (ΔTqref2k) per each cylinder and the standard injection period correction quantity (ΔTqref1k) stored in a memory exceeds the determined value in the condition that FCCB correction is performed to the Tq correction quantity (ΔTqref2k) per each cylinder of a four-cylinder diesel engine, when quantity of deterioration with the lapse of time of any one of injectors 5 per each cylinder is determined more than the determined value, the Tq correction quantity (ΔTqk) in the injection condition except for the FCCB correcting condition (condition having a command injection quantity and a common rail pressure different from the idle stabilized condition) is computed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a command injection period calculated from a command injection amount set according to an engine speed and an accelerator opening and a fuel injection pressure detected by a sensor, that is, a multi-cylinder engine. For an internal combustion engine that controls the injection amount to each cylinder of a multi-cylinder engine by driving the injector for each cylinder according to the energization time of the injector drive signal to the solenoid valve of the injector mounted on each cylinder of the engine The present invention relates to an injection amount control device.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection system for a diesel engine, a common rail type fuel injection system is known in which high pressure fuel accumulated in a common rail is injected into each cylinder of an engine through an injector. In the case of this common rail fuel injection system,
The command injection amount is calculated according to the engine speed and the accelerator opening, the injection start timing is calculated according to the engine speed and the command injection amount, and the fuel injection pressure and the command injection detected by the fuel pressure sensor and the like are calculated. The command injection period (the energization time of the injector drive current) is calculated from the amount, and the injector drive current is applied to the solenoid valve of the injector from the injection start timing to the end of the energization time to control the injection amount of the injector. There is.

[0003]

However, the fuel injection quantity injected and supplied into each cylinder of the engine usually has a variation in the actual injection quantity with respect to the energization time of the injector drive current (injection command pulse length). Although it is guaranteed by adjusting the individual injectors for each cylinder, as shown in the graph of FIG. 8, the command injection amount or the actual injection amount is changed due to the change over time of the injection function of the injector, that is, the deterioration of the injector over time (function). There is a problem that the deviation amount of the injection command pulse length (Tq) with respect to the amount changes with time. In order to solve the problem, there is a well-known technique for suppressing the injection amount fluctuation control between cylinders (disproportionate amount compensation control / FCCB).
Correction) is known.

However, the FCCB correction described above is carried out for the purpose of suppressing engine vibration that occurs in response to fluctuations in rotational speed between cylinders in an idle stable state in which the command injection amount and fuel injection pressure are low or in no-load fuel consumption conditions. Because of the control, the injection condition is in the stable idle state (FCCB
(Correction execution condition) or no-load fuel consumption condition to control the injection amount fluctuation between cylinders, and FCCB correction execution is performed for the command injection amount and fuel injection pressure that are mainly used during actual engine operation. There is a problem that it is not possible to suppress the injection amount variation between the cylinders under other injection conditions different from the conditions, particularly after the injector deteriorates with time.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to suppress the injection amount fluctuation between cylinders not only when the injection condition is a predetermined injection condition in which the command injection amount and the fuel injection pressure are low, but also under other injection conditions. It is an object of the present invention to provide an injection amount control device for an internal combustion engine, which enables control to be performed and improves injection amount control accuracy. Another object of the present invention is to provide an injection amount control device for an internal combustion engine, which can suppress the injection amount variation between cylinders after the injector deteriorates with time.

[0006]

According to the invention as set forth in claim 1, the rotational speed fluctuation for each cylinder is detected when at least a predetermined injection condition with a low command injection amount and a low fuel injection pressure is detected. , Comparing the detected value of the rotational speed fluctuation of each cylinder and the average value of the rotational speed fluctuation of all cylinders, the characteristics of the command injection amount and the command injection period are set so as to smooth the rotational speed fluctuation between the cylinders. Suppresses fluctuations in injection amount between cylinders that are individually adjusted. Then, the injection period correction amount for each cylinder under a predetermined injection condition is calculated according to the deviation between the detected value of the rotational speed fluctuation of each cylinder and the average value of the rotational speed fluctuations of all the cylinders.

Then, the injection period correction amount for each cylinder under the predetermined injection condition is set according to the command injection amount and the fuel injection pressure under the injection condition different from the predetermined injection condition. Even when the injection condition is not only the idle stable state where the command injection amount and the fuel injection pressure are low, the FCCB correction execution condition or the no-load fuel consumption condition, but also other injection conditions, Since it becomes possible to carry out the injection amount fluctuation suppression control in the above, it is possible to improve the injection amount control accuracy.

According to the second aspect of the present invention, when the deviation between the injection period correction amount for each cylinder and the reference injection period correction amount under a predetermined injection condition is a predetermined value or more, each cylinder It can be determined that the time-dependent deterioration amount of each injector is equal to or greater than the determination value. According to the third aspect of the present invention, when the time-dependent deterioration detecting unit detects that the time-dependent deterioration amount of the injector for each cylinder is equal to or greater than the determination value, each cylinder under a predetermined injection condition. By updating and storing the injection period correction amount for each cylinder as the reference injection period correction amount for each cylinder, from the next time on the basis of the updated reference injection period correction amount for each cylinder, Deterioration of the injector over time can be determined.

According to the invention described in claim 4, when it is detected by the aging deterioration detecting means that the aging deterioration amount of the injector for each cylinder is equal to or more than the judgment value, By reflecting the injection period correction amount for each cylinder in the calculation of the injection period correction amount for each cylinder under an injection condition different from the predetermined injection condition, after the injector deteriorates with time, the injection condition is at least the command injection amount and The injection amount variation suppression control between the cylinders can be performed not only under a predetermined injection condition with a low fuel injection pressure but also under other injection conditions.

According to the fifth aspect of the present invention, when the time-dependent deterioration detecting means detects that the time-dependent deterioration amount of the injector for each cylinder is equal to or more than the judgment value, the fuel injection different from the predetermined injection condition is performed. By calculating the injection period correction amount for each cylinder due to deterioration over time due to changes in pressure or changes in command injection amount that differ from predetermined injection conditions, after the injector deteriorates with time, the injection conditions are at least the command injection amount and the fuel injection pressure. Not only low injection conditions of low
Even under other injection conditions, the injection amount variation suppression control between cylinders can be performed.

According to the sixth aspect of the present invention, the injection period correction amount for each cylinder under the predetermined injection condition is set to ΔTqref, and the injection pressure correction is made in consideration of the change of the fuel injection pressure different from the predetermined injection condition. When the coefficient is α and the injection period correction amount for each cylinder due to deterioration over time in the same command injection amount due to changes in fuel injection pressure is ΔTq1k, the relationship of ΔTq1k = α × ΔTqref is satisfied. There is.

According to the seventh aspect of the invention, the injection period correction amount for each cylinder under the predetermined injection condition is set to ΔTqref, and the injection amount correction is made in consideration of the change of the command injection amount different from the predetermined injection condition. If the coefficient is β and the same fuel injection pressure,
It is characterized in that the relationship ΔTq2k = β × ΔTqref is satisfied, where ΔTq2k is the injection period correction amount for each cylinder due to deterioration over time due to changes in the command injection amount.

According to the invention described in claim 8, the injection period correction amount for each cylinder under the predetermined injection condition is set to ΔTqref, and the injection pressure correction is made in consideration of the change of the fuel injection pressure different from the predetermined injection condition. The coefficient is α, the injection amount correction coefficient considering the change in the command injection amount that is different from the predetermined injection condition is β, and the injection period correction amount for each cylinder due to deterioration over time in the change of the fuel injection pressure and the change of the command injection amount ΔTqk
In this case, the relation ΔTqk = α × β × ΔTqref is satisfied.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION [Structure of Embodiment] An embodiment of the present invention will be described based on an embodiment with reference to the drawings. here,
FIG. 1 is a diagram showing the overall configuration of a common rail fuel injection system.

The common rail fuel injection system of this embodiment accumulates high-pressure fuel corresponding to the fuel injection pressure to be injected and supplied to each cylinder of a multi-cylinder engine (internal combustion engine: hereinafter referred to as engine) 1 such as a 4-cylinder diesel engine. Common rail 2 as a pressure accumulator, a fuel supply pump (supply pump) 3 that pressurizes the sucked fuel and pumps it into the common rail 2, and injects high pressure fuel accumulated in the common rail 2 into each cylinder of the engine 1. A plurality of (four in this example) electromagnetic fuel injection valves (hereinafter referred to as injectors) 5 to be supplied, and an electronic control unit (hereinafter referred to as ECU) 10 for electronically controlling the supply pump 3 and the plurality of injectors 5. Is equipped with.

The high pressure fuel corresponding to the fuel injection pressure must be continuously accumulated in the common rail 2, and therefore the high pressure fuel accumulated in the common rail 2 is supplied from the supply pump 3 via the fuel injection pipe 11. Is being supplied.
A pressure limiter 13 for releasing the pressure is attached to the relief pipe 14 for relieving the fuel from the common rail 2 to the fuel tank 7 so that the common rail pressure does not exceed the limit set pressure.

The supply pump 3 is a suction metering type high pressure supply pump which pressurizes the fuel and discharges the high pressure fuel from the discharge port to the common rail 2. The supply pump 3 is a well-known feed pump (low pressure supply pump) that pumps the fuel in the fuel tank 7 by rotating the pump drive shaft 16 with the rotation of a crank shaft (crank shaft) 15 as an output shaft of the engine 1. : Not shown), a cam (not shown) rotationally driven by the pump drive shaft 16, and one or more cams driven by the cam to reciprocate between a top dead center and a bottom dead center. A plunger (not shown), one or more pressurizing chambers (plunger chambers: not shown) that pressurize the sucked fuel as the one or more plungers slide back and forth in the cylinder, and the pressurization It has a discharge valve (not shown) that opens when the fuel pressure in the chamber rises above a predetermined value.

Further, the supply pump 3 is provided with a leak port so that the fuel temperature in the pump chamber does not become high, and the leak fuel from the supply pump 3 is
From the fuel return passage 17 through the fuel return passage 19 to the fuel tank 7
Will be returned to. By adjusting the opening degree (opening degree) of the fuel flow path for guiding the fuel from the feed pump of the supply pump 3 to the pressurization chamber, the fuel flow from the supply pump 3 to the common rail 2 is adjusted. An intake metering valve 4 as an electromagnetic actuator that changes the discharge amount is attached.

The intake metering valve 4 is electronically controlled by a pump drive signal from the ECU 10 via a pump drive circuit (not shown) to adjust the intake amount of fuel sucked into the pressurizing chamber of the supply pump 3. An intake valve solenoid valve is used to change the common rail pressure corresponding to the fuel injection pressure that is injected and supplied from each injector 5 into each cylinder of the engine 1. The intake metering valve 4 is a normally open type solenoid valve in which the valve state is fully opened when the energization is stopped.

The injector 5 mounted on each cylinder of the engine 1 is connected to the downstream ends of a plurality of branch pipes (fuel injection pipes) 12 branched from the common rail 2 and accommodates a nozzle needle for opening and closing the injection hole. A fuel injection nozzle, an electromagnetic actuator that drives the nozzle needle of the fuel injection nozzle in the valve opening direction, and an urging means such as a spring that urges the nozzle needle in the valve closing direction.

Fuel injection from these injectors 5 to the engine 1 is performed by energizing and energizing an injection control solenoid valve (hereinafter abbreviated as solenoid valve) as an electromagnetic actuator for controlling the pressure in the back pressure control chamber of the nozzle needle. Stop (ON
/ OFF) to electronically control. That is, while the solenoid valve of the injector 5 of each cylinder is open, the high pressure fuel accumulated in the common rail 2 is injected and supplied into each cylinder of the engine 1. Here, the leaked fuel from the injector 5 or the discharged fuel (return fuel) from the back pressure control chamber of the nozzle needle is configured to flow back from the fuel return passage 18 to the fuel return passage 19 to the fuel tank 7. .

The ECU 10 includes a CPU for performing control processing and arithmetic processing, and a storage device (ROM, standby RAM or EEPRO) for storing various programs and data.
There is provided a microcomputer having a well-known structure including functions such as M, a memory such as RAM, an input circuit, an output circuit, a power supply circuit, an injector drive circuit (EDU), a pump drive circuit, and the like.

The voltage signal from the fuel pressure sensor 25 and the sensor signals from other various sensors are A / D.
After being A / D converted by the converter, it is input to a microcomputer incorporated in the ECU 10. Further, when the engine key is returned to the IG position after the engine 1 is cranked and an ignition switch (not shown) is turned on (ON), the ECU 10, for example, supplies the pump 3 or the like based on the control program stored in the memory. The actuator of each control component such as the injector 5 is configured to be electronically controlled.

Here, the microcomputer has a crank angle sensor for detecting a rotation angle of a crankshaft (crankshaft) 15 of the engine 1 as a driving condition detecting means for detecting a driving state or a driving condition of the engine 1. 21, an accelerator opening sensor 22 for detecting an accelerator opening (ACCP), an engine cooling water temperature (TH
Cooling water temperature sensor 23 for detecting W) and the fuel temperature (T
A fuel temperature sensor 24 or the like for detecting (HF) is connected.

Of the above sensors, the crank angle sensor 2
1 is a crankshaft 1 of the engine 1
5 or an NE timing rotor (not shown) attached to the pump drive shaft 16 of the supply pump 3 so as to face the outer periphery thereof. A plurality of convex teeth are arranged at a predetermined angle on the outer peripheral surface of the NE timing rotor, and the reference position of each cylinder (upper position) is set so as to correspond to each cylinder of the engine 1. Four dead tooth portions for determining the dead center position: TDC position) are provided at a predetermined angle (180 ° CA).

The crank angle sensor 21 is composed of an electromagnetic pickup, and each convex tooth of the NE timing rotor moves toward and away from the crank angle sensor 21 to generate a pulse-shaped rotational position signal (N) by electromagnetic induction.
E signal pulse) is output. The ECU 10 measures the interval time of the NE signal pulses output from the crank angle sensor 21 to determine the engine speed (N
It functions as a rotation speed detecting means for detecting E).

Further, the ECU 10 determines that the engine rotation speed is a predetermined value (for example, NE = 1000 rpm) or less, the accelerator opening is a predetermined value (for example, ACCP = 0%) or less, and the vehicle traveling speed (hereinafter, referred to as vehicle speed) is a predetermined value. (For example SPD = 0
command injection amount is a predetermined value (for example, QFIN)
= 5 mm ³ / st) or less, when it is detected that the transmission gear position is N (neutral), it is in a low load low rotation state, that is, in an idle stable state (FCCB correction execution condition) or no load fuel consumption state. It is configured to include a function of a no-load fuel consumption detecting means for detecting

The ECU 10 calculates the optimum fuel injection pressure (hereinafter referred to as common rail pressure) according to the operating conditions of the engine 1, and drives the intake metering valve 4 of the supply pump 3 via the pump drive circuit. Discharge rate control means (SC
V control means). That is, the ECU 10
Engine rotation speed (NE) detected by the rotation speed detection means such as the crank angle sensor 21 and accelerator opening (ACCP) detected by the accelerator opening sensor 22.
The target fuel pressure (PFIN) is calculated from the engine operation information such as the above and the command injection amount (QFIN), and in order to achieve this target fuel pressure (PFIN), the pump drive to the intake metering valve 4 of the supply pump 3 is performed. The signal (driving current value) is adjusted to control the pumping amount of fuel discharged from the supply pump 3 (pump discharge amount).

More preferably, for the purpose of improving the control accuracy of the fuel injection amount, the common rail pressure (NPC) detected by the fuel pressure sensor 25 and the target fuel pressure (PFIN) determined by the engine operating information and the like. It is desirable to feedback-control the pump drive signal to the suction metering valve 4 of the supply pump 3 so that they substantially match. The control of the drive current value (SCV energization value) to the intake metering valve 4 is preferably performed by duty control. That is, the target fuel pressure (PFI
ON / OFF of the pump drive signal per unit time according to N)
By using the duty control for changing the valve opening of the intake metering valve 4 by adjusting the off ratio (energization time ratio / duty ratio), highly accurate digital control becomes possible.

Further, the ECU 10 corresponds to an injection amount control device for individually controlling the fuel injection amount injected and supplied from the injector 5 of each cylinder into each cylinder of the engine 1. This is the engine speed (NE) and accelerator opening (ACC
P) and a characteristic map (see FIG. 2) previously measured by experiments and the like (see FIG. 2) to calculate an optimum basic injection amount (Q), and an engine cooling water temperature (TH)
W) and a command injection amount determination means for calculating the command injection amount (QFIN) by adding the injection amount correction amount to the basic injection amount (Q) according to operating conditions such as the fuel temperature on the pump suction side (THF).
From the common rail pressure (NPC), the command injection amount (QFIN), and the characteristic map (see FIG. 3) created in advance through experiments and the like, the energization period (injection command pulse length, injection command pulse width) to the solenoid valve of the injector 5 , Injection command pulse time: Tq), and an injector 5 of each cylinder via an injection period determining means and an injector drive circuit (EDU).
Injector drive means for applying a pulsed injector drive current (INJ injection command pulse, TQ pulse) to the solenoid valve.

Here, FIG. 4 shows the injection command pulse length (= injection amount command value) of a specific cylinder (for example, # 1 cylinder), and the specific cylinder (for example, # 1 cylinder) corresponding to this injection command pulse length. 5 is a timing chart showing an injector drive current waveform output to the solenoid valve of the injector 5 and a fuel injection rate of a specific cylinder (for example, # 1 cylinder). Also,
The ECU 10 of the present embodiment detects the rotation speed fluctuation of each cylinder of the engine 1 for each explosion stroke in the idle stable state,
Each cylinder of the engine 1 is compared with the detected value of the rotation speed fluctuation of each cylinder of the engine 1 and the average value of the rotation speed fluctuations of all the cylinders so as to smooth the rotation speed fluctuation between the cylinders of the engine 1. Rotational speed fluctuation inter-cylinder correction (FCCB) for individually adjusting the optimum fuel injection amount for each is performed.

Further, the ECU 10 of the present embodiment may give an unpleasant engine vibration to a driver (driver) due to a decrease in idling speed during idling.
Even if the engine load torque changes, the target idle speed is maintained so that engine noise and fuel consumption rate are not deteriorated by preventing engine stall or by increasing idling speed. It is configured to perform an idling rotation speed control (ISC) for controlling the injection amount required for. It is desirable that the fuel injection amount be feedback-controlled so that the current engine rotation speed substantially matches the target rotation speed.

[Control Method of Embodiment] Next, a control method for suppressing the variation of the injection amount between the cylinders of this embodiment will be briefly described with reference to FIGS. 1 to 12. Here, FIG. 5 is a flowchart showing a control method for suppressing the variation of the injection amount between the cylinders.

The control routine shown in FIG. 5 is executed when the injector 5 is installed in the engine 1 or the injector 5 is replaced with a new one. At the timing of entering the control routine of FIG. 5, it is determined whether or not the FCCB correction execution condition for suppressing the variation in the injection amount between the cylinders is satisfied. That is, it is determined whether or not the FCCB correction execution flag (inter-cylinder injection amount fluctuation correction flag: XFCCB) is set (step S1). This determination result is NO
In the case of, the control routine of FIG. 5 is exited.

For example, as shown in FIG. 6, the engine speed (NE) is a predetermined value (KNEFCCB: eg 10).
00 rpm) or less, the shift lever or select lever is set to the neutral (N) state or the gear position is set to the neutral (N), the ISC execution flag (XISC) is set, the ISC idle flag (XIDLISC) is set, and the engine cooling water temperature (THW) ) Is a predetermined value (KFCC
BTH: For example, 60 ° C. or more, vehicle speed (SPD) is a predetermined value (for example, 0 km / h) or less, accelerator opening (ACCP)
Is fully closed, the common rail pressure (NPC) is a predetermined value (eg, 100 MPa) or less, the command injection amount (QFIN) is larger than the lower limit value (KQFCCBL: 0 mm ³ / st), and the upper limit value (KQFCCBH: 30 mm ^3).
/ St) and all the following conditions are satisfied for 2 seconds or more, the FCCB correction execution flag (XF
CCB) is established (set). In addition, the FCCB correction execution flag (XFCCB) is not established under the conditions other than the conditions shown in FIG.

When an ON signal of the parking brake is detected, the drive load of engine accessories such as an alternator, water pump, oil pump, headlight, car audio, air conditioner switch, heater switch, fan switch for blower, etc. When the engine load such as the electric load of the vehicle increases or decreases, or when the select lever is in the N range or P
By combining input information such as when it is detected that the range is set or when the driver (driver) is stepping on the clutch pedal, the idle stable state of the engine 1 (FCCB The correction execution condition) may be detected. In addition, when an assembling worker such as assembling the injector 5 to the engine 1 or an inspection worker inserts the service tool into a predetermined portion, or long-presses an existing switch, or simultaneously presses a plurality of existing switches. FCCB
The correction may be performed.

When the determination result of step S1 is YES, that is, when the FCCB correction execution condition is set, the injection amount variation amount difference between the cylinders of the engine 1
By performing the inter-cylinder injection amount fluctuation suppression correction (hereinafter referred to as FCCB correction) that increases or decreases the injection command pulse length (Tq) for each cylinder with respect to the command injection amount (QFIN), the rotational speed fluctuation between the cylinders is reduced. A command that is set according to the engine rotation speed (NE) detected by the rotation speed detection means such as the crank angle sensor 21 and the accelerator opening (ACCP) detected by the accelerator opening sensor 22 so as to be smoothed. In the command injection period (injection command pulse length: Tq base value) corresponding to the injection amount (QFIN), the FCCB correction amount (Tq correction amount: ΔTqref1k) in the direction of smoothing the rotational speed fluctuation between the cylinders, respectively. Add (step S2).

In the FCCB correction, specifically, the interval time of the NE signal pulse taken in from the crank angle sensor 21 is calculated to calculate the instantaneous rotation speed of each cylinder of the engine 1 for each explosion stroke, and BTDC 90 °. CA-ATDC
The maximum value of the interval time of the NE signal pulse between 90 ° CA is read as the minimum rotation speed (hereinafter, referred to as the minimum rotation speed: Nl) of the instantaneous rotation speed of the cylinder. Also, BTDC 90 °
The minimum value of the interval time of the NE signal pulse between CA and ATDC 90 ° CA is read as the maximum rotation speed (hereinafter, referred to as the maximum rotation speed: Nh) of the instantaneous rotation speed of the cylinder. However, Nl and Nh do not necessarily have to be the minimum rotation speed and the maximum rotation speed, and may be the low rotation speed and the high rotation speed representing the rotation speed fluctuation of the cylinder.

After performing these calculations for each cylinder, the cylinder-by-cylinder rotational speed difference (ΔNk) between the maximum rotational speed (Nh) for each cylinder and the minimum rotational speed (Nl) for each cylinder is calculated. To do. Thereby, the detected value of the rotation speed fluctuation for each cylinder of the engine 1 is calculated. Then, the average value (ΣΔNk) of the rotational speed fluctuations of all the cylinders of the engine 1 is calculated. That is, the rotational speed fluctuations of all cylinders of the engine 1 are averaged,
After calculating the average value of the rotational speed fluctuations of all the cylinders, the deviation of the rotational speed fluctuations between the cylinders is calculated from the detected value of the rotational speed fluctuations of each cylinder and the average value of the rotational speed fluctuations of all the cylinders. Then, the Tq correction amount in the direction of smoothing the rotation speed variation between the cylinders is added to the injection amount of each injection calculated for each cylinder so that the rotation speed variation between the cylinders of engine 1 is smoothed. Increase (ΔTqref1k) for each cylinder.

Next, the FC for each cylinder, which is the injection period correction amount for each cylinder, under the FCCB correction execution condition in the initial state.
CB correction amount (Tq change amount, Tq correction amount; ΔTqref1k)
Is stored in a memory such as a standby RAM or an EEPROM or a RAM (step S3). Next, the Tq correction amount (ΔTqref1k) for each cylinder under the FCCB correction execution condition in the initial state is stored as a reference injection period correction amount for each cylinder in a memory such as a standby RAM or EEPROM, RAM ( Step S4).

Here, FIG. 7 is a flow chart showing a control method for suppressing the variation of the injection amount between the cylinders. In the control routine of FIG. 7, after the ignition switch is turned on, a predetermined timing (for example, when the traveling distance is 50
It is executed every 0 to 10000 km). This Figure 7
When it comes to the timing of entering the control routine of No. 6, it is determined whether or not the FCCB correction execution condition shown in FIG. 6 is satisfied. That is, it is determined whether or not the FCCB correction execution flag (cylinder injection amount variation correction flag: XFCCB) is set (step S11). If the determination result is NO, the control routine of FIG. 7 is exited.

Further, the determination result of step S11 is YES.
In the case of, the FCCB for increasing / decreasing the injection command pulse length (Tq) for each cylinder with respect to the command injection amount (QFIN) according to the difference in the injection amount fluctuation amount between the cylinders of the engine 1 in the same manner as described above. Correction is performed (step S12). next,
The FCCB correction amount (Tq change amount, Tq correction amount; ΔTqref2k) for each cylinder, which is the injection period correction amount for each cylinder at the time of FCCB correction after the lapse of a predetermined time for each cylinder, is stored in the standby RAM or EEPROM. , RAM or the like (step S13).

Next, the injector (INJ) deterioration determination with time is performed for each injector 5 for each cylinder.
That is, Tq for each cylinder under FCCB correction execution conditions
Correction amount (ΔTqref2k) and reference injection period correction amount (ΔTqref2k)
It is determined whether the deviation from ref1k) is greater than or equal to the deterioration determination value (aging deterioration detection means: step S14). If the determination result is NO, the control routine of FIG. 7 is exited.

Further, the determination result of step S14 is YES.
In this case, it is determined that the amount of deterioration over time of one or more injectors 5 among the injectors 5 for each cylinder is equal to or greater than the determination value, and the correction start flag is set from 0 to 1. Is used to calculate the Tq correction amount (ΔTqk) for each cylinder under injection conditions other than the FCCB correction execution condition (injection period correction amount determination means: step S15).

Next, the engine rotation speed (N is detected by the rotation speed detecting means such as the crank angle sensor 21).
E) and the command injection period (injection command pulse length: Tq base value) corresponding to the command injection amount (QFIN) set according to the accelerator opening (ACCP) detected by the accelerator opening sensor 22. Tq correction amount for each cylinder (ΔT
qk) is added to the corrected injection command pulse length (Tq +
ΔTqk) is calculated (correction amount reflecting means: step S1)
6). Next, T for each cylinder under the FCCB correction execution condition
Standby R with q correction amount (ΔTqref2k) as reference injection period correction amount (ΔTqref1K ← ΔTqref2k) for each cylinder
It is stored in a memory such as AM or EEPROM, RAM (step S17). After that, the control routine of FIG. 7 is exited.

[Characteristics of Embodiment] Next, the Tq correction amount (ΔT) for each cylinder under injection conditions other than the FCCB correction execution condition.
A processing method for calculating qk) will be described with reference to FIGS.

Conventionally, for controlling the injection amount of the injector 5 for each cylinder, at least the engine rotation speed (NE), the accelerator opening (ACCP), and a characteristic map (see FIG. 2) prepared by measurement in advance by experiments or the like are used. The optimum basic injection amount (Q) is calculated by the command, and the basic injection amount (Q) is added with the injection amount correction amount according to operating conditions such as engine cooling water temperature (THW) and fuel temperature on the pump intake side (THF) The injection amount (QFIN) is calculated, and the command injection timing (TFI) is calculated according to the engine speed (NE) and the command injection amount (QFIN).
N) is calculated, and the relationship between the common rail pressure (NPC) detected by the fuel pressure sensor 25, the command injection amount (QFIN), and the command injection period (the energization time of the injector drive current, the injection command pulse length: Tq) is calculated. The injection command pulse length (Tq) is calculated on the basis of a characteristic map (Q-Tq map: see FIG. 3) that is measured and created in advance, and the command injection timing (TFIN) is calculated as shown in FIG. ) To the injection command pulse length (Tq), the INJ injection command pulse (injector drive current) is applied to the solenoid valve of the injector 5.

Here, the initial characteristics of the high injection pressure (high pressure) and the low injection pressure (low pressure) when the injector 5 is assembled are shown by the solid line in the graph of FIG. The time-dependent characteristics of the injection pressure (high pressure) and the low injection pressure (low pressure) are shown by the broken line in the graph of FIG.
From the graph of FIG. 8, the injection command pulse length (Tq) deviation amount due to deterioration over time under the FCCB correction execution condition is ΔTqref, but the command injection amount increases even with the same injection pressure as the FCCB correction execution condition. Injection command pulse length (T
The amount of deviation of the injection command pulse length (Tq) due to deterioration over time in Point 1 in which q) becomes long is ΔTqLH, and ΔTqre
It can be confirmed that ΔTqLH is larger than f.

Further, under the injection condition of a higher pressure than the FCCB correction execution condition, the injection command pulse length (Tq) deviation amount due to the deterioration over time in Point 2 when the same command injection amount as the FCCB correction execution condition is ΔTqHL. , The injection command pulse length (Tq) is longer than that, and the injection command pulse length (Tq) becomes longer due to deterioration over time in Point3.
q) The amount of deviation is ΔTqHH, which is ΔTqHH rather than ΔTqHL.
It can be confirmed that is larger.

Next, when the injection command pulse length (Tq) deviation amount due to deterioration over time is sorted by the Tq deviation amount under the FCCB correction execution condition, the following pattern is obtained.

(1) When the injection pressure correction coefficient (α) has a peculiar value: The Tq deviation amount due to the time-dependent change at each point at the same common rail pressure (NPC) is constant, and the common rail pressure (NPC).
When the amount of Tq deviation due to the change of PC) changes (ΔTqref =
ΔTqLH, ΔTqHL = ΔTqHH) is shown in FIG.
As shown in the graph of (b), each common rail pressure (N
PC) Tq deviation due to change over time (ΔTq1k)
Can be calculated based on the following arithmetic expression.

[Equation 1]

Here, α is an injection pressure correction coefficient corresponding to the inclination component due to the common rail pressure (NPC), and is shown in FIG.
As shown in (a), two points are interpolated with a one-dimensional map for the common rail pressure (NPC). Further, ΔTqref is Tq under the FCCB correction execution condition (low pressure, small injection amount).
This is the correction amount.

(2) When the injection amount correction coefficient (β) has a unique value Even with the same common rail pressure (NPC), the command injection amount (Q
When the amount of Tq deviation due to the change of FIN) changes (ΔTqref
≠ ΔTqLH, ΔTqHL ≠ ΔTqHH)
As shown in the graphs of (a) and (b), the Tq deviation amount (ΔTq2k) due to the time-dependent change due to each command injection amount (QFIN) at the same common rail pressure (NPC) is calculated by the following formula 2. Can be calculated based on

[Equation 2]

However, β is an injection amount correction coefficient corresponding to the inclination component due to the command injection amount (QFIN), and FIG.
As shown in (b), two-point interpolation is performed with a one-dimensional map for the command injection amount (QFIN). Also, ΔTqref is F
It is the Tq correction amount under the CCB correction execution condition (low pressure, small injection amount).

From the above, each common rail pressure (NPC)
And T due to changes over time in each command injection amount (QFIN)
The q deviation amount (ΔTqk) can be calculated based on the following arithmetic expression of Expression 3.

[Equation 3]

However, α is the inclination component due to the common rail pressure (NPC), β is the inclination component due to the command injection amount (QFIN), and ΔTqref is Tq under the FCCB correction execution condition (low pressure, small injection amount). This is the correction amount.

(3) When the inclination components of the correction coefficients (α, β) cannot be expressed individually When the inclination components of the correction coefficients (α, β) cannot be expressed individually, they are shown in FIG. From the α × β coefficient value map, the correction coefficient value (map value: γ) is interpolated at four points with a two-dimensional map of common rail pressure (NPC) and command injection amount (QFIN) to calculate ΔTqk, and ΔT
Multiply qref.

[Equation 4]

Then, ΔTqk calculated as described above
To the engine speed (NE) and accelerator opening (ACC
P), the command injection amount (QFIN), the common rail pressure (NPC), and the injection command pulse length (Tq)
Tq-q created by measuring the relationship with
In the injection command pulse length (Tq base value) on the map, T
The q correction amount (ΔTqk) is added up for each cylinder to calculate the corrected injection command pulse length (Tq + ΔTqk).

As a result, when the command injection timing (TFIN) is reached, the solenoid valve of the injector 5 for each cylinder is started to be energized by the injector drive current (INJ injection command pulse), and then the corrected injection command pulse is applied. Length (T
When q + ΔTqk) is reached, energization is stopped so that the actual injection amount injected and supplied from the injector 5 for each cylinder into each cylinder of the engine 1 is the command injection amount (QFI).
N) and the variation in the injection amount between the cylinders is suppressed.

[Effects of Embodiment] As described above, in the common rail fuel injection system of this embodiment, the Tq correction amount (ΔTqref2k) for each cylinder is Tq correction for each cylinder under the FCCB correction execution condition. When the deviation between the amount (ΔTqref2k) and the reference injection period correction amount (ΔTqref1k) is equal to or greater than the determination value, one of the injectors 5 for each cylinder is selected.
When it is determined that the amount of deterioration over time of one or more injectors 5 is equal to or greater than the determination value, Tq correction under injection conditions other than FCCB correction execution conditions (conditions in which the command injection amount and the common rail pressure differ from the idle stable state) The quantity (ΔTqk) is calculated.

Therefore, the Tq correction amount (ΔTqk) under the injection condition other than the FCCB correction execution condition (the condition where the command injection amount and the common rail pressure are different from the idle stable state).
Therefore, the injection amount corresponding to the command injection amount and the common rail pressure can be obtained by using the Tq correction amount (ΔTqref2k) for each cylinder stored in the memory as a correction value in the entire use region of the command injection amount and the common rail pressure in the actual vehicle. It can be reflected in the calculation of the command pulse length (Tq).
As a result, the correlation between the ideal injection command pulse length and the actual injection amount can be obtained individually for each cylinder. Further, in contrast to the conventional method in which the correction is limited to the common rail pressure in the idle stable state, the injection condition is not only the FCCB correction execution condition of at least low pressure and small injection amount (idle stable state) but also other conditions. Even under the injection condition, the injection amount variation suppression control between the cylinders can be performed,
The injection amount control accuracy can be improved.

Further, due to the above FCCB correction, the total Tq correction amount (ΔTqref1k) is more than a predetermined value, or the difference between the previous Tq correction amount (ΔTqref1k) and the current Tq correction amount (ΔTqref2k) is outside the predetermined range. If it is, it is possible to detect that there is a variation in the injection amount that is greater than or equal to a predetermined value with respect to the injection command pulse length (Tq value) of the base value in the reference Tq-Q map. The driver may be urged to replace the individual injector 5 by turning on the light.

The FCCB correction execution flag (inter-cylinder injection amount variation correction flag: XFCCB) is XFCCB = 1 under the conditions shown in the control logic of FIG. 6, but the conditions for entering the INJ aging deterioration determination mode are: It is desirable to set more stable conditions (engine cooling water temperature, engine rotation condition, command injection amount, etc.). Under that condition, FCCB
The correction amount (Tq correction amount) is compared, but as the span,
Stable data comparison for a long time is naturally good, but if the stable idle stable state such as waiting for a signal is set to 15 seconds and the idle rotation speed (NE = 850 rpm) is set, the engine 1 rotates 212.5 rpm. If there are four cylinders, the FCCB correction amount can be sampled about 100 times per cylinder. Further, in this, a guard for the Tq correction amount is provided, and the value stored when the condition is satisfied and the Tq correction amount are compared.

The FCC shown in the control routine of FIG.
The deterioration determination value in the B correction amount comparison differs depending on the specifications of the injector 5. However, according to the specification of a certain injector 5, the common rail pressure (NPC = 25MP) during idle operation is used.
a), the command injection amount (QFIN = 5 mm ³ / st), the difference between the command injection amount (QFIN) and the actual injection amount (ΔQ) =
At 0.5 mm ³ / st, the Tq change amount is ≈30 μsec from the Tq-Q characteristic, and ΔQ = 0.5 mm ³ /
When st is used as the judgment value, ΔTqref = 30 can be used as the deterioration judgment value.

[Modification] In the present embodiment, an example in which the present invention is applied to the pilot injection amount learning control device of the common rail fuel injection system for a diesel engine is shown.
The present invention may be applied to an injection amount control device for an internal combustion engine that does not include a common rail but includes an electronically controlled distributed fuel injection pump, an electronically controlled column fuel injection pump, or the like. Further, in the present embodiment, the example in which the injector 5 including the electromagnetic fuel injection valve is used has been described, but an injector including a piezoelectric fuel injection valve may be used.

In this embodiment, the standby RAM or the EEPROM is used as the correction amount storage means, but the EPROM, the EEPROM or the like is used without using the standby RAM or the EEPROM.
Non-volatile memory such as flash memory, DVD-RO
Another storage medium such as M, a CD-ROM, or a flexible disk may be used to store the previous Tq correction amount updated by the previous FCCB correction. Also in this case, turn off the ignition switch (I
The stored contents are preserved even after G / OFF) or after the engine key is removed from the key cylinder.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a common rail fuel injection system (embodiment).

FIG. 2 is a characteristic diagram showing a relationship among an engine speed, an accelerator opening, and a basic injection amount (Example).

FIG. 3 is a characteristic diagram showing a relationship among a command injection amount, a common rail pressure, and an injection command pulse length (Example).

FIG. 4 is a timing chart showing an injector injection command pulse, an injector drive current waveform, and a fuel injection rate (Example).

FIG. 5 is a flowchart showing a control method for suppressing a variation in injection amount between cylinders (embodiment).

FIG. 6 is a block diagram showing FCCB correction execution conditions (embodiment).

FIG. 7 is a flowchart showing a control method for suppressing variation in injection amount between cylinders (embodiment).

FIG. 8 is a graph showing a relationship among an injection amount, a common rail pressure, and an injection command pulse length (Example).

9A is a characteristic diagram showing a Tq correction amount under an FCCB correction execution condition with respect to a Tq deviation amount due to a change over time at each point, and FIG. 9B is an injection pressure correction coefficient (α) with respect to a common rail pressure. It is the characteristic diagram shown (Example).

10A is a characteristic diagram showing an injection pressure correction coefficient (α) with respect to a common rail pressure, and FIG. 10B is a characteristic diagram showing an injection amount correction coefficient (β) with respect to a command injection amount (Example). ).

FIG. 11 (a) is Tq due to change with time at each point.
FIG. 6B is a characteristic diagram showing the Tq correction amount under the FCCB correction execution condition with respect to the deviation amount, and FIG. 7B is a characteristic diagram showing the injection amount correction coefficient (β) with respect to the command injection amount (Example).

FIG. 12 is a characteristic diagram showing a relationship among a common rail pressure, a command injection amount, and a correction coefficient value (map value) (Example).

[Explanation of symbols]

1 Engine (Internal Combustion Engine) 2 Common Rail (Accumulator) 3 Supply Pump (Fuel Supply Pump) 5 Injector (Electromagnetic Fuel Injection Valve) 10 ECU (Correction Amount Calculation Means, Correction Amount Reflection Means, Aging Degradation Detection Means, Correction Amount Storage Means, injection period correction amount determining means) 21 crank angle sensor (operating condition detecting means) 22 accelerator opening sensor (operating condition detecting means) 25 fuel pressure sensor (fuel pressure detecting means)

Continued front page    F term (reference) 3G084 BA13 BA21 DA22 DA23 EA11                       EB08 EB11 EB17 EB25 EC06                       FA05 FA06 FA07 FA10 FA20                       FA34 FA39                 3G301 HA02 HA04 JA05 JA15 LA05                       MA11 NA01 NA08 NC01 ND01                       ND21 ND41 PB01Z PB03Z                       PB08Z PE02Z PE04Z PE08Z                       PF01Z PF03Z PF10Z PF11Z                       PF12Z PF13Z

Claims (8)

[Claims] 1. A command injection period of an injector mounted for each cylinder of a multi-cylinder engine is calculated from at least a command injection amount and a fuel injection pressure which are set in accordance with an engine speed and an engine load. In an injection amount control device for an internal combustion engine, which drives an injector for each cylinder according to a calculated command injection period to control an injection amount to each cylinder of the multi-cylinder engine, (a) at least a command injection amount and When a predetermined injection condition with low fuel injection pressure is detected, the rotational speed fluctuation for each cylinder is detected, and the detected value of the rotational speed fluctuation for each cylinder and the average value of the rotational speed fluctuations of all cylinders are compared. , The injection speed variation between cylinders is controlled by individually adjusting the characteristics of the command injection quantity and the command injection period so as to smooth the rotation speed fluctuation between the cylinders, and the rotation speed of each cylinder Correction amount calculation means for calculating an injection period correction amount for each cylinder under the predetermined injection condition in accordance with a deviation between a detected value of fluctuation and an average value of rotational speed fluctuations of all cylinders; The injection period correction amount for each cylinder under the predetermined injection condition is reflected in the calculation of the command injection period set according to the command injection amount and the fuel injection pressure under the injection condition different from the predetermined injection condition. An injection amount control device for an internal combustion engine, comprising: 2. The injection amount control apparatus for an internal combustion engine according to claim 1, wherein the correction amount reflecting means is an injection period correction amount for each cylinder under the predetermined injection condition and a reference injection period correction amount. The injection amount control device for an internal combustion engine, comprising: a time-dependent deterioration detection unit that detects that the time-dependent deterioration amount of the injector for each cylinder is equal to or larger than a determination value when the deviation from the predetermined value is a predetermined value or more. 3. The injection amount control apparatus for an internal combustion engine according to claim 2, wherein the correction amount reflecting means has a deterioration amount with time of the injector for each cylinder that is equal to or greater than a determination value by the deterioration detecting means. Is detected, the injection period correction amount for each cylinder under the predetermined injection condition is updated as a reference injection period correction amount for each cylinder, and a correction amount storage unit is stored. Injection amount control device for internal combustion engine. 4. The injection amount control device for an internal combustion engine according to claim 2 or 3, wherein the correction amount reflecting means determines the deterioration amount with time of the injector for each cylinder by the deterioration determination means. When it is detected that the above, the injection period correction amount of each cylinder under the predetermined injection conditions, the injection period correction amount of each cylinder under the injection conditions different from the predetermined injection conditions An injection amount control device for an internal combustion engine, which is reflected in calculation. 5. The injection amount control device for an internal combustion engine according to any one of claims 2 to 4, wherein the correction amount reflecting means is a time-dependent deterioration detecting means for the injector for each cylinder. When it is detected that the deterioration amount is equal to or greater than the determination value, the injection of each cylinder due to the deterioration over time in the change of the fuel injection pressure different from the predetermined injection condition or the change of the command injection amount different from the predetermined injection condition. An injection amount control device for an internal combustion engine, comprising an injection period correction amount determining means for calculating a period correction amount. 6. The injection amount control device for an internal combustion engine according to claim 5, wherein an injection period correction amount for each cylinder under the predetermined injection condition is ΔTqref, and a fuel injection pressure different from the predetermined injection condition. Is set to α, and the injection period correction amount for each cylinder due to deterioration over time due to the change in the fuel injection pressure with the same command injection amount is ΔT.
An injection amount control device for an internal combustion engine, characterized in that the relationship ΔTq1k = α × ΔTqref is satisfied when q1k. 7. The injection amount control device for an internal combustion engine according to claim 5, wherein an injection period correction amount for each cylinder under the predetermined injection condition is ΔTqref, and a command injection amount different from the predetermined injection condition. Let β be the injection amount correction coefficient that takes into account the change in
An injection amount control device for an internal combustion engine, which satisfies a relationship of ΔTq2k = β × ΔTqref when q2k. 8. The injection amount control device for an internal combustion engine according to claim 5, wherein an injection period correction amount for each cylinder under the predetermined injection condition is ΔTqref, and a fuel injection pressure different from the predetermined injection condition. Of the injection pressure correction coefficient in consideration of the change of the predetermined injection condition, and the injection amount correction coefficient of β in consideration of the change of the command injection amount different from the predetermined injection condition, and in the change of the fuel injection pressure and the change of the command injection amount The injection period correction amount for each cylinder due to deterioration over time is ΔT
An injection amount control apparatus for an internal combustion engine, characterized in that the relationship ΔTqk = α × β × ΔTqref is satisfied, where qk.