Method for regenerating exhaust gas purifying filter apparatus

Abstract

The present invention relates to a method for regenerating a filter that traps particulate matter contained in exhaust gas of an internal combustion engine. The regeneration method includes increasing an amount of soot having a low degree of graphitization in the filter. After the amount of soot having the low degree of graphitization is increased, a temperature of the filter is increased.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a system to which an embodiment of the invention is applied;

FIG. 2 is a control flowchart (No. 1) of the embodiment of FIG. 1;

FIG. 3 is a control flowchart (No. 2) of the embodiment of FIG. 1;

FIG. 4 is a control flowchart (No. 3) of the embodiment of FIG. 1;

FIG. 5 is a control flowchart (No. 4) of the embodiment of FIG. 1;

FIG. 6 is a schematic structural diagram of a system to which an alternative embodiment of the invention is applied;

FIG. 7 is a control flowchart (No. 1) of the embodiment of FIG. 6;

FIG. 8 is a control flowchart (No. 2) of the embodiment of FIG. 6;

FIG. 9 is a control flowchart (No. 3) of the embodiment of FIG. 6;

FIG. 10 is a control flowchart (No. 4) of the embodiment of FIG. 6;

FIG. 11 is a control flowchart (No. 5) of the embodiment of FIG. 6;

FIG. 12 is a graph showing the relationship between the degree of graphitization and the in-cylinder temperature and dwell time (engine speed);

FIG. 13 is a graph showing the relationship between the burning temperature of the soot and the degree of graphitization;

FIG. 14 is a graph showing the relationship between the in-cylinder temperature and EGR ratio;

FIG. 15 is a graph showing the relationship between the in-cylinder temperature and the main injection timing during the expansion stroke; and

FIG. 16A is an illustration of PM with soot having a low degree of graphitization and FIG. 16B is an illustration of PM with soot having a high degree of graphitization.

Claims

1. A method for regenerating a filter of the type that traps particulate matter contained in exhaust gas of an internal combustion engine, the method comprising: increasing an amount of soot having a low degree of graphitization in the filter; andincreasing a temperature of the filter after the amount of the soot having the low degree of graphitization is increased.

2. The method of claim 1, wherein the amount of the soot having the low degree of graphitization in the filter is increased by operating the internal combustion engine under conditions that decrease an in-cylinder temperature.

3. The method according of claim 1, wherein the soot having the low degree of graphitization in the filter is increased by operating the internal combustion engine accompanied by at least one control of the engine operation selected from: an increase in exhaust gas recirculation (EGR) amount, retardation of a main fuel injection timing, a decrease in an intake air temperature, a decrease in a compression ratio, an increase in an amount of assist from a motor that assists output of the internal combustion engine, and a decrease in power output from the internal combustion engine.

4. The method of claim 1, wherein the amount of the soot having the low degree of graphitization in the filter is increased by operating the internal combustion engine under conditions that shorten a time that cylinder gas dwells in a cylinder.

5. The method of claim 1, wherein the amount of the soot having the low degree of graphitization in the filter is increased by operating the internal combustion engine accompanied by at least one control of the engine selected from: an increase in engine speed and an advancement of timing for opening an exhaust gas valve.

6. The method according of claim 1, further comprising: determining an amount of the particulate matter trapped in the filter, and wherein the amount of the soot having the low degree of graphitization is increased after the amount of the particulate matter trapped in the filter reaches a predetermined amount.

7. The method of claim 1, further comprising: increasing the temperature of the filter to a temperature at which the soot having the low degree of graphitization in the filter burns.

8. The method of claim 7, wherein the temperature at which the soot having the low degree of graphitization in the filter burns is in a range of about 500° C. to about 600° C.

9. A method for regenerating a filter of the type that traps particulate matter contained in exhaust gas of an internal combustion engine, the method comprising: operating the internal combustion engine under operating conditions that decrease an in-cylinder temperature or that shorten a time cylinder gas dwells in a cylinder; andincreasing a temperature of the filter after the operating of the internal combustion engine is continued under the operating conditions for a predetermined time.

10. The method of claim 9, wherein the operating of the internal combustion engine, under the operating conditions that decrease the in-cylinder temperature or that shorten the time cylinder gas dwells in the cylinder, is accompanied by at least one control of the engine selected from: an increase in exhaust gas recirculation (EGR) amount, retardation of main fuel injection timing, a decrease in intake temperature, a decrease in compression ratio, an increase in amount of assist from a motor that assists output of the internal combustion engine, a decrease in output of the internal combustion engine, an increase in engine speed, and an advancement of timing for opening an exhaust gas valve.

11. An apparatus for purifying exhaust gas from an internal combustion engine, comprising: a filter that traps particulate matter contained in exhaust gas of the internal combustion engine; anda controller connected to the internal combustion engine, wherein the controller operates the internal combustion engine so as to increase an amount of soot having a low degree of graphitization in the filter and, after the amount of the soot having the low degree of graphitization is increased, operates the internal combustion engine so as to increase a temperature of the filter.

12. The apparatus of claim 11, wherein the controller operates the internal combustion to increase the amount of soot having the low degree of graphitization in the filter under operating conditions that decrease an in-cylinder temperature.

13. The apparatus of claim 11, wherein the controller operates the internal combustion engine to increase the amount of the soot having the low degree of graphitization in the filter by at least one control selected from an increase in exhaust gas recirculation (EGR) amount, retardation of a main fuel injection timing, a decrease in an intake temperature, a decrease in a compression ratio, an increase in an amount of assist from a motor that assists output of the internal combustion engine, and a decrease in output power of the internal engine.

14. The apparatus of claim 11, wherein the controller operates the internal combustion engine to increases the amount of the soot having the low degree of graphitization in the filter under operating conditions that shorten a time cylinder gas dwells in a cylinder.

15. The apparatus of claim 11, wherein the amount of the soot having the low degree of graphitization in the filter is increased by the controller operating the internal combustion engine accompanied by at least one control selected from: an increase in engine speed and an advancement of timing for opening an exhaust gas valve.

16. The apparatus of claim 11, wherein the controller determines an amount of particulate matter trapped in the filter and operates the internal combustion engine so as to increase the amount of the soot having the low degree of graphitization in the filter after the amount of the particulate matter trapped in the filter is determined to reach a predetermined amount.

17. The apparatus of claim 11, wherein the controller operates the internal combustion engine so as to increase the temperature of the filter to a temperature at which the soot having the low degree of graphitization in the filter burns.

18. The apparatus of claim 17, wherein the temperature at which the soot having the low degree of graphitization in the filter burns is in a range of about 500° C. to about 600° C.

19. An apparatus for purifying exhaust gas from an internal combustion engine, comprising: a filter that traps particulate matter contained in exhaust gas of the internal combustion engine; anda controller connected to the internal combustion engine,wherein the controller operates the internal combustion engine under operating conditions that decrease an in-cylinder temperature or that shorten a time cylinder gas dwells in a cylinder and, after the operating of the internal combustion engine is continued under the operating conditions for a predetermined time, operates the internal combustion engine to increase a temperature of the filter.

20. The apparatus of claim 19, wherein the operating of the internal combustion engine under the operating conditions that decrease the in-cylinder temperature or that shorten the time the cylinder gas dwells in the cylinder is accompanied by at least one control selected from an increase in exhaust gas recirculation (EGR) amount, retardation of main fuel injection timing, a decrease in intake temperature, a decrease in compression ratio, an increase in amount of assist from a motor that assists output of the internal combustion engine, a decrease in output of the internal engine, an increase in engine speed, and advancement of timing for opening an exhaust gas valve.

21. Means for regenerating a filter of the type that traps particulate matter contained in exhaust gas of an internal combustion engine, comprising: means for increasing an amount of soot having a low degree of graphitization in the filter, andmeans for increasing a temperature of the filter up to a temperature at which the soot having the low degree of graphitization in the filter burns, after the amount of the soot having the low degree of graphitization in the filter is increased.