Method and system for gasoline particulate filter operations

Patent metadata

Field	Value
Publication number	US-10066575-B2
Application number	US-201615211536-A
Country	US
Kind code	B2
Filing date	Jul 15, 2016
Priority date	Jul 15, 2016
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

Methods and systems are provided for optimal operation of a gasoline particulate filter coupled to an engine exhaust system. Based on engine operating conditions, a target soot level on the GPF may be determined, and one or more engine operating parameters may be adjusted to maintain the actual GPF soot level at the target level. In one example, if the actual GPF soot level is lower than the target level, one or more of a fuel injection timing and a fuel rail pressure may be adjusted to increase soot generation, and if the actual GPF soot level is higher than the target level, the GPF may be regenerated until the actual soot level reaches the target level.

First claim

The invention claimed is:

1. A method for an engine comprising:
responsive to each of a current soot level at an exhaust particulate filter being lower than a target soot level and an ash level at the exhaust particulate filter being lower than a threshold ash level, adjusting one or more of a fuel injection timing and a fuel injection pressure to increase soot output of the engine until the current soot level is at the target soot level, the target soot level varied based on engine temperature and engine load.

2. The method of claim 1 , wherein the target soot level is varied to maintain a capture rate of soot at the filter above a threshold capture rate, and the target soot level is set to a first target soot level during engine start conditions when the engine temperature is below a threshold temperature and the engine speed is below a threshold speed, the target soot level is set to a second target soot level during engine idling conditions when the engine temperature is above the threshold temperature and the engine speed is below the threshold speed, and the target soot level is set to a third target soot level when the engine temperature is above the threshold temperature and the engine speed is above the threshold speed, wherein the first target soot level, the second target soot level, and the third target soot level are distinct from each other.

3. The method of claim 2 , wherein the first target soot level is based on a fuel injection schedule during the engine start conditions, the second target soot level is based on a fuel injection schedule during the engine idling conditions, and the third target soot level is based on a fuel injection schedule when the engine temperature is above the threshold temperature and the engine speed is above the threshold speed, wherein the fuel injection schedules include one or more of a split ratio of a fuel injected via a port fuel injector relative to the fuel injected via a direct fuel injector, a split ratio of the fuel injected via the direct fuel injector during a compression stroke relative to the fuel injected via the direct fuel injector during an intake stroke, and a number of fuel injections via the direct fuel injector per fueling event during the compression stroke.

4. The method of claim 1 , further comprising estimating an ash level of the filter based on each of a duration of regeneration and a regeneration temperature for one or more prior regeneration events of the filter, and further varying the target soot level based on the estimated ash level to maintain an aggregated ash and soot load of the filter within a threshold load.

5. The method of claim 1 , wherein adjusting one or more of the fuel injection timing and the fuel injection pressure includes advancing the fuel injection timing and decreasing fuel injection pressure to actively raise the soot output of the engine.

6. The method of claim 5 , wherein advancing the fuel injection timing includes advancing one or more of a start of injection timing, an end of injection timing, and an average injection timing.

7. The method of claim 6 , wherein a degree of advancing the start of injection timing and a degree of reducing the fuel injection pressure is increased as a difference between the target soot level and the current soot level increases.

8. The method of claim 1 , further comprising, responsive to the current soot level at the exhaust particulate filter being higher than the target soot level, initiating filter regeneration, and responsive to a rate of filter regeneration being higher than a threshold rate, retarding spark timing to generate soot at the engine while continuing to regenerate the filter.

9. The method of claim 8 , wherein an amount of spark retard applied is increased as the rate of filter regeneration exceeds the threshold rate.

10. The method of claim 1 , wherein the engine is fueled with gasoline, and wherein the filter is a gasoline particulate filter.

11. A method for an engine, comprising:
responsive to each of a soot load of an exhaust particulate filter being lower than a threshold load and an ash level of the exhaust particulate filter being lower than a threshold ash level, increasing engine soot output until the soot load is at the threshold load; and
responsive to the soot load being higher than the threshold load, irrespective of the ash level of the exhaust particulate filter, regenerating the filter while retarding spark timing until the soot load is at the threshold load.

12. The method of claim 11 , wherein increasing engine soot output includes one or more of advancing a start of injection timing of a cylinder fuel injection and decreasing a fuel rail pressure to actively generate soot at the engine and raise the soot load of the exhaust particulate filter.

13. The method of claim 12 , wherein an amount of injection timing advance and an amount of fuel rail pressure reduction is increased as the soot load falls below the threshold load.

14. The method of claim 11 , wherein regenerating the filter while retarding spark timing includes increasing an amount of spark retard with an increase in a rate of regeneration of the filter while continuing to regenerate the filter.

15. The method of claim 11 , wherein the ash level is estimated based on a duration of filter regeneration and wherein the soot load is estimated based on a pressure differential across the filter.

16. An engine system comprising:
an engine including a cylinder;
an exhaust passage receiving combustion gases from the cylinder;
a gasoline particulate filter (GPF), coupled to the exhaust passage;
one or more pressure sensors coupled to the GPF;
one or more temperature sensors coupled to the GPF;
an electric circuit coupled to the GPF, the electric circuit including an electric switch;
a fueling system including a fuel rail, a fuel tank, a fuel pump, and a fuel injector for delivering fuel to the engine cylinder; and
a controller with computer readable instructions stored on non-transitory memory for:
inferring a current soot load of the GPF based on inputs of the one or more pressure sensors and temperature sensors;
inferring an actual ash load of the GPF based on a duration of actuation of the switch during a GPF regeneration; and
in response to each of the current soot load falling below a target load and the actual ash load falling below a threshold ash load, increasing soot output by the engine by advancing a timing of actuating the fuel injector or decreasing a pressure of the fuel rail until the current soot load is at the target load.

17. The system of claim 16 , wherein the controller includes further instructions for:
selecting the target load based on each of an engine temperature, an engine speed, and an engine load, the target load increased with one or more of a decrease in the engine temperature, an increase in the engine speed, and an increase in the engine load.

18. The system of claim 16 , wherein the controller includes further instructions for:
following the GPF regeneration, maintaining an aggregate of the current soot load and the actual ash load at the target load by advancing the timing of actuating the fuel injector.

19. The system of claim 16 , wherein the controller includes further instructions for:
as the current soot load exceeds the target load, regenerating the filter to reduce the soot load on the filter, a rate of the regenerating adjusted by retarding spark timing to increase engine soot output until the current soot load is at the target load.

20. The met

Assignees

• Ford Global Tech Llc

Inventors

• Suchta Nikodem
• Lymburner Jacqueline A
• Van Nieuwstadt Michiel J
• Hedges John Edward

Classifications

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F01N3/023

  using means for regenerating the filters, e.g. by burning trapped particles · CPC title

• F02D41/3836

  Controlling the fuel pressure · CPC title

• F02D41/029

  the exhaust gas treating apparatus being a particulate filter · CPC title

• F02D41/0235

  in relation with the state of the exhaust gas treating apparatus (control of exhaust gas treating apparatus per se F01N) · CPC title