Fuel injection control system of internal combustion engine

Patent metadata

Field	Value
Publication number	US-2016245211-A1
Application number	US-201415027335-A
Country	US
Kind code	A1
Filing date	Oct 7, 2014
Priority date	Oct 11, 2013
Publication date	Aug 25, 2016
Grant date	—

Abstract

At least after off of an injection pulse of partial lift injection, a first filtered voltage Vsm1 being a negative terminal voltage Vm of a fuel injection valve filtered by a first low-pass filter having a first frequency f1 as a cutoff frequency, the first frequency f1 being lower than a frequency of a noise component, is acquired, and a second filtered voltage Vsm2 being the negative terminal voltage Vm filtered by a second low-pass filter having a second frequency f2 as a cutoff frequency, the second frequency f2 being lower than the first frequency f1, is acquired. Time from a predetermined reference timing to a timing when a difference Vdiff (=Vsm1−Vsm2) between the filtered voltages has an inflection point is calculated as voltage inflection time Tdiff, and the injection pulse of the partial lift injection is corrected based on the voltage inflection time Tdiff.

First claim

1 . A fuel injection control system of an internal combustion engine having an electromagnetic driving fuel injection valve, the fuel injection control system comprising:
an injection control portion that performs partial lift injection to drive the fuel injection valve to open with an injection pulse allowing a lift amount of a valve element of the fuel injection valve not to reach a full lift position; a filtered-voltage acquisition portion that, after off of an injection pulse of the partial lift injection, acquires a first filtered voltage being a terminal voltage of the fuel injection valve filtered by a first low-pass filter having a first frequency as a cutoff frequency, the first frequency being lower than a frequency of a noise component, and acquires a second filtered voltage being the terminal voltage filtered by a second low-pass filter having a second frequency as a cutoff frequency, the second frequency being lower than the first frequency; a difference calculation portion that calculates a difference between the first filtered voltage and the second filtered voltage; a time calculation portion that calculates time from a predetermined reference timing to a timing when the difference has an inflection point as voltage inflection time; and an injection pulse correction portion that corrects the injection pulse of the partial lift injection based on the voltage inflection time.

2 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein the first low-pass filter and the second low-pass filter are each a digital filter.

3 . The fuel injection control system of the internal combustion engine according to claim 2 , wherein the first low-pass filter is a digital filter implemented by Formula (1) that uses a previous value Vsm1(k−1) of the first filtered voltage and a current value Vm(k) of the terminal voltage to obtain a current value Vsm1(k) of the first filtered voltage, a sampling frequency fs of the terminal voltage and the cutoff frequency f1 of the first low-pass filter satisfying a relationship of Formula (2),
Vsm 1( k )={( n 1−1)/ n 1}× Vsm 1( k− 1)+(1/ n 1)× Vm ( k )  (1),

1/ fs: 1/ f 1=1:( n 1−1)  (2).

4 . The fuel injection control system of the internal combustion engine according to claim 2 , wherein the second low-pass filter is a digital filter implemented by Formula (3) that uses a previous value Vsm2(k−1) of the second filtered voltage and a current value Vm(k) of the terminal voltage to obtain a current value Vsm2(k) of the second filtered voltage, a sampling frequency fs of the terminal voltage and the cutoff frequency f2 of the second low-pass filter satisfying a relationship of Formula (4),
Vsm 2( k )={( n 2−1)/ n 2}× Vsm 2( k− 1)+(1/ n 2)× Vm ( k )  (3),

1/ fs: 1/ f 2=1:( n 2−1)  (4).

5 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein the time calculation portion calculates the voltage inflection time with a timing when the difference exceeds a predetermined threshold as the timing when the difference has the inflection point.

6 . The fuel injection control system of the internal combustion engine according to claim 1 ,
wherein the filtered-voltage acquisition portion acquires a third filtered voltage being the difference filtered by a third low-pass filter having a third frequency as a cutoff frequency, the third frequency being lower than a frequency of a noise component, and acquires a fourth filtered voltage being the difference filtered by a fourth low-pass filter having a fourth frequency as the cutoff frequency, the fourth frequency being lower than the third frequency, wherein the difference calculation portion calculates a difference between the third filtered voltage and the fourth filtered voltage as a second order differential, and wherein the time calculation portion calculates the voltage inflection time with a timing when the second order differential has an extreme value as the timing when the difference has the inflection point.

7 . The fuel injection control system of the internal combustion engine according to claim 6 , wherein when the second order differential no longer increases, the time calculation portion determines the second order differential has the extreme value.

8 . The fuel injection control system of the internal combustion engine according to claim 6 , wherein the third low-pass filter and the fourth low-pass filter are each a digital filter.

9 . The fuel injection control system of the internal combustion engine according to claim 8 , wherein the third low-pass filter is a digital filter implemented by Formula (5) that uses a previous value Vdiff.sm3(k−1) of the third filtered voltage and a current value Vdiff(k) of the difference to obtain a current value Vdiff.sm3(k) of the third filtered voltage, a sampling frequency fs of the terminal voltage and the cutoff frequency of the third low-pass filter satisfying a relationship of Formula (6),
V diff. sm 3( k )={( n 3−1)/ n 3 }×V diff. sm 3( k− 1)+(1/ n 3)× V diff( k )  (5),

1/ fs: 1/ f 3=1:( n 3−1)  (6).

10 . The fuel injection control system of the internal combustion engine according to claim 8 , wherein the fourth low-pass filter is a digital filter implemented by Formula (7) that uses a previous value Vdiff.sm4(k−1) of the fourth filtered voltage and a current value Vdiff(k) of the difference to obtain a current value Vdiff.sm4(k) of the fourth filtered voltage, a sampling frequency fs of the terminal voltage and the cutoff frequency f4 of the fourth low-pass filter satisfying a relationship of Formula (8),
V diff. sm 4( k )={( n 4−1)/ n 4 }×V diff. sm 4( k− 1)+(1/ n 4)× V diff( k )  (7),

1/ fs: 1/ f 4=1:( n 4−1)  (8).

11 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein a drive IC of the fuel injection valve collectively serves as the filtered-voltage acquisition portion, the difference calculation portion, and the time calculation portion.

12 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein a calculation IC provided separately from the drive IC of the fuel injection valve collectively serves as the filtered-voltage acquisition portion, the difference calculation portion, and the time calculation portion.

13 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein a microcomputer controlling the internal combustion engine collectively serves as the filtered-voltage acquisition portion, the difference calculation portion, and the time calculation portion.

14 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein the time calculation portion calculates the voltage inflection time with the reference timing being a timing when the injection pulse of the partial lift injection is switched from off to on.

15 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein the time calculation portion calculates the voltage inflection time with the reference timing being a timing when the injection pulse of the partial lift injection is switched from on to off.

16 . The fuel injection control system of the internal combustion engine according to claim 1 , wherein the time calculation portion calculates the voltage inflection time with the reference timing being a timing when the terminal voltage becomes lower than a predetermined value after off of the injection pulse of the partial lift injection.

Assignees

• Denso Corp

Inventors

• Katsurahara Hiroshi
• Satake Nobuyuki

Classifications

• F02D2041/2055

  with means for determining actual opening or closing time · CPC title

• F02D41/1402

  Adaptive control · CPC title

• F02D2041/1432

  the system including a filter, e.g. a low pass or high pass filter · CPC title

• F02D41/20

  Output circuits, e.g. for controlling currents in command coils · CPC title

• F02D41/2467 Primary

  for injectors · CPC title