Closed loop A/F ratio control for diesel engines using an oxygen sensor

• US 7,137,386 B1
• Filed: 09/02/2005
• Issued: 11/21/2006
• Est. Priority Date: 09/02/2005
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Ruiz, Victoriano
• Primary Examiner(s): Gimie, Mahmoud
• Application Number:
  US11/219,412
• Time in Patent Office: 445 Days
• Field of Search: 123/674, 123/486, 123/703, 123/672, 123/478, 123/480
• US Class Current: 123/674
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02D 2250/32 Air-fuel ratio control in a diesel engine
• CPC Class Codes: F02D 41/029 the exhaust gas treating apparatus being a particulate filter
• CPC Class Codes: F02D 41/2441 characterised by the learning conditions
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control
• CPC Class Codes: F02D 41/38 of the high pressure type

Abstract

A fuel control system for a diesel engine includes a first module that calculates a block learn multiplier (BLM) based on a feedback signal during a closed-loop fuel control period. A second module adjusts a base fueling rate of the diesel engine based on the BLM during an open-loop fuel control period.

Claims

1. A fuel control system for a diesel engine, comprising:

a first module that selectively regulates operation of said diesel engine in one of a closed-loop air to fuel ratio (A/F) control mode and an open-loop A/F control mode;

a second module that calculates a block learn multiplier (BLM) based on a feedback signal when said first module operates said diesel engine in said closed-loop A/F control mode; and

a third module that adjusts a base fueling rate of said diesel engine based on said BLM when said first module operates said diesel engine in said open-loop A/F control mode.

2. The fuel control system of claim 1 wherein said base fueling rate is determined from a look-up table based on an engine speed (RPM) and an engine load.

3. The fuel control system of claim 1 wherein said base fueling rate is adjusted based on a ratio between said BLM and a neutral BLM value.

4. The fuel control system of claim 1 further comprising an oxygen sensor that generates an oxygen sensor signal (OSS) based on an oxygen content of exhaust from said diesel engine, wherein said feedback signal is said OSS.

5. The fuel control system of claim 1 wherein said third module determines said base fueling rate from a look-up table and determines an adjusted fueling rate based on said BLM and said base fueling rate.

6. The fuel control system of claim 5 wherein said BLM is extrapolated across engine operating ranges of said look-up table to provide a plurality of BLMs, wherein said fueling rate is adjusted based on one of said plurality of BLMs.

7. A method of regulating fueling of a diesel engine, comprising:

selectively regulating operation of said diesel engine in one of a closed-loop air to fuel ratio (A/F) control mode and an open-loop A/F control mode;

calculating a block learn multiplier (BLM) based on a feedback signal during said closed-loop A/F control mode; and

adjusting a base fueling rate of said diesel engine based on said BLM during said open-loop A/F control mode.

8. The method of claim 7 further comprising determining said base fueling rate from a look-up table based on an engine speed (RPM) and an engine load.

9. The method of claim 7 wherein said fueling rate is adjusted based on a ratio between said BLM and a neutral BLM value.

10. The method of claim 7 further comprising generating an oxygen sensor signal (OSS) based on an oxygen content of exhaust from said diesel engine, wherein said feedback signal is said OSS.

11. The method of claim 7 further comprising:

determining said base fueling rate from a look-up table; and

calculating an adjusted fueling rate based on said BLM and said base fueling rate.

12. The method of claim 11 further comprising extrapolating said BLM across engine operating ranges of said look-up table to provide a plurality of BLMs, wherein said fueling rate is adjusted based on one of said plurality of BLMs.

13. A method of regulating fueling of a diesel engine during an open-loop air to fuel ratio (A/F) control mode, comprising:

initiating a closed-loop A/F control mode;

generating a feedback signal;

calculating a block learn multiplier (BLM) based on said feedback signal during said closed-loop A/F control mode;

initiating said open-loop A/F control mode; and

adjusting a base fueling rate of said diesel engine based on said BLM during said open-loop A/F control mode.

14. The method of claim 13 further comprising determining said base fueling rate from a look-up table based on an engine speed (RPM) and an engine load.

15. The method of claim 13 wherein said fueling rate is adjusted based on a ratio between said BLM and a neutral BLM value.

16. The method of claim 13 further comprising generating an oxygen sensor signal (OSS) based on an oxygen content of exhaust from said diesel engine, wherein said feedback signal is said OSS.

17. The method of claim 13 further comprising:

determining said base fueling rate from a look-up table; and

calculating an adjusted fueling rate based on said BLM and said base fueling rate.

18. The method of claim 17 further comprising extrapolating said BLM across engine operating ranges of said look-up table to provide a plurality of BLMs, wherein said fueling rate is adjusted based on one of said plurality of BLMs.