AIR/FUEL MIXTURE IMBALANCE DIAGNOSTIC SYSTEMS AND METHODS

• US 20100082297A1
• Filed: 12/02/2008
• Published: 04/01/2010
• Est. Priority Date: 10/01/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: TURIN, RAYMOND CLAUDE, Bagnasco, Andrew P., Mac Ewen, Ian J., Majors, Steven Ward
• Granted Patent: US 8,577,645 B2
• Time in Patent Office: Days
• US Class Current: 702/183
• CPC Class Codes: F02D 2041/1417 Kalman filter
• CPC Class Codes: F02D 41/0085 Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/1498 measuring engine roughness
• CPC Class Codes: G01M 15/104 using oxygen or lambda-sensors testing catalytic converters F01N3/18, F01N11/007

Abstract

An air/fuel imbalance (AFIM) diagnostic system comprises a first module, an imbalance determination module, and an imbalance diagnostic module. The first module outputs imbalance data samples based on an oxygen signal provided by an oxygen sensor measuring oxygen in exhaust expelled from cylinders of a cylinder bank. The imbalance determination module determines an AFIM value based on the imbalance data samples. The imbalance diagnostic module selectively diagnoses an AFIM in the cylinder bank based on the AFIM value.

Claims

1. An air/fuel imbalance (AFIM) diagnostic system comprising:

a first module that outputs imbalance data samples based on an oxygen signal provided by an oxygen sensor measuring oxygen in exhaust expelled from cylinders of a cylinder bank;

an imbalance determination module that determines an AFIM value based on said imbalance data samples; and

an imbalance diagnostic module that selectively diagnoses an AFIM in said cylinder bank based on said AFIM value.

2. The AFIM system of claim 1 wherein said imbalance diagnostic module diagnoses said AFIM when said AFIM value is greater than a predetermined value.

3. The AFIM system of claim 1 wherein said first module applies a filter to said oxygen signal, and

wherein said imbalance data samples correspond to outputs of said filter.

4. The AFIM system of claim 3 wherein said filter is a Kalman filter.

5. The AFIM system of claim 1 wherein said imbalance determination module determines said AFIM value based on a variance of said imbalance data samples.

6. The AFIM system of claim 5 wherein said imbalance determination module determines said AFIM value based on an average of a square of each of said imbalance data samples from a mean of said imbalance data samples.

7. The AFIM system of claim 5 wherein said imbalance determination module determines said AFIM value based on the equation:

8. The AFIM system of claim 1 wherein said first module outputs said imbalance data samples based on firing events of said cylinders.

9. The AFIM system of claim 1 wherein said first module outputs said imbalance data samples when each of said cylinders is fired and between when each of said cylinders is fired.

10. The AFIM system of claim 1 further comprising a cylinder identification module that attributes said AFIM to one of said cylinders when said AFIM is diagnosed.

11. An air/fuel imbalance (AFIM) diagnostic method comprising:

outputting imbalance data samples based on an oxygen signal provided by an oxygen sensor measuring oxygen in exhaust expelled from cylinders of a cylinder bank;

determining an AFIM value based on said imbalance data samples; and

selectively diagnosing an AFIM in said cylinder bank based on said AFIM value.

12. The AFIM diagnostic method of claim 11 wherein said selectively diagnosing said AFIM comprises diagnosing said AFIM when said AFIM value is greater than a predetermined value.

13. The AFIM diagnostic method of claim 11 further comprising applying a filter to said oxygen signal,

wherein said imbalance data samples correspond to outputs of said filter.

14. The AFIM diagnostic method of claim 13 wherein said filter is a Kalman filter.

15. The AFIM diagnostic method of claim 11 wherein said determining said AFIM value comprises determining said AFIM value based on a variance of said imbalance data samples.

16. The AFIM diagnostic method of claim 15 wherein said determining said AFIM value comprises determining said AFIM value based on an average of a square of each of said imbalance data samples from a mean of said imbalance data samples.

17. The AFIM diagnostic method of claim 15 wherein said determining said AFIM value comprises determining said AFIM value based on the equation:

18. The AFIM diagnostic method of claim 11 wherein said outputting comprises outputting said imbalance data samples based on firing events of said cylinders.

19. The AFIM diagnostic method of claim 11 wherein said outputting comprises outputting said imbalance data samples when each of said cylinders is fired and between when each of said cylinders is fired.

20. The AFIM diagnostic method of claim 11 further comprising attributing said AFIM to one of said cylinders when said AFIM is diagnosed.