Fuel control strategy for heating a catalyst

• US 7,934,487 B2
• Filed: 06/10/2009
• Issued: 05/03/2011
• Est. Priority Date: 06/10/2009
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Roos, Bryan Nathaniel, Gonze, Eugene V., Santoso, Halim G., Spohn, Brian
• Primary Examiner(s): Huynh; Hai H
• Application Number:
  US12/481,957
• Publication Number:
  US 20100318281A1
• Time in Patent Office: 692 Days
• Field of Search: 123/676, 123/691, 123/692, 123/443, 123/685, 123/686, 123/435, 701103-105, 701/109, 602/85, 602/86
• US Class Current: 123/435
• CPC Class Codes: B01D 53/9454 characterised by a specific device
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: F01N 13/107 More than one exhaust manifold or exhaust collector
• CPC Class Codes: F01N 2430/06 by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• CPC Class Codes: F01N 3/2006 Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• CPC Class Codes: F01N 9/00 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 Class Codes: F02D 2200/021 Engine temperature
• CPC Class Codes: F02D 2200/0802 Temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/025 by changing the composition of the exhaust gas, e.g. for exothermic reaction on exhaust gas treating apparatus
• CPC Class Codes: F02D 41/0255 to accelerate the warming-up of the exhaust gas treating apparatus at engine start
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A control system for an engine having N cylinders in first and second banks includes a catalyst heat module and a fuel control module. N is an integer greater than two. The catalyst heat module selectively operates the engine in a catalyst heat mode to heat a catalyst. The fuel control module, throughout a fuel injection sequence for each of the N cylinders, adjusts a first air/fuel (A/F) ratio for the first bank to a rich value and adjusts a second A/F ratio for the second bank to a lean value.

Claims

1. A control system for an engine having N cylinders in first and second banks, wherein N is an integer greater than two, comprising:

a catalyst heat module that, based on an engine coolant temperature, selectively operates the engine in a catalyst heat mode to heat a catalyst; and

a fuel control module that, throughout a fuel injection sequence for each of the N cylinders, adjusts a first air/fuel (A/F) ratio for the first bank to a rich value and adjusts a second A/F ratio for the second bank to a lean value.

2. The control system of claim 1, wherein a first distance between the first bank and the catalyst is greater than a second distance between the second bank and the catalyst.

3. The control system of claim 1, wherein the fuel control module determines the first A/F ratio based on a first oxygen level in exhaust gas from the first bank and determines the second A/F ratio based on a second oxygen level in exhaust gas from the second bank.

4. The control system of claim 1, wherein the fuel control module adjusts the first A/F ratio by controlling a first amount of fuel injected into the first bank and adjusts the second A/F ratio by controlling a second amount of fuel injected into the second bank.

5. The control system of claim 1, wherein the catalyst heat module initiates the catalyst heat mode during a cold start of the engine.

6. The control system of claim 5, wherein the cold start occurs when the engine is started and the engine coolant temperature is less than an operating temperature.

7. The control system of claim 5, wherein the catalyst heat module terminates the catalyst heat mode when a catalyst temperature is greater than or equal to a light-off temperature.

8. The control system of claim 1, wherein the catalyst is at least one of an electrically-heated catalyst and a three-way catalyst.

9. The control system of claim 1, wherein the lean value is equal to approximately 11.5 and the rich value is equal to approximately 16.

10. The control system of claim 1, wherein the lean value is equal to approximately 13 and the rich value is equal to approximately 16.

11. A method for an engine having N cylinders in first and second banks, wherein N is an integer greater than two, comprising:

selectively operating the engine in a catalyst heat mode to heat a catalyst based on an engine coolant temperature; and

throughout a fuel injection sequence for each of the N cylinders, adjusting a first air/fuel (A/F) ratio for the first bank to a rich value and adjusting a second A/F ratio for the second bank to a lean value.

12. The method of claim 11, wherein a first distance between the first bank and the catalyst is greater than a second distance between the second bank and the catalyst.

13. The method of claim 11, further comprising determining the first A/F ratio based on a first oxygen level in exhaust gas from the first bank and determining the second A/F ratio based on a second oxygen level in exhaust gas from the second bank.

14. The method of claim 11, further comprising adjusting the first A/F ratio by controlling a first amount of fuel injected into the first bank and adjusting the second A/F ratio by controlling a second amount of fuel injected into the second bank.

15. The method of claim 11, further comprising initiating the catalyst heat mode during a cold start of the engine.

16. The method of claim 15, wherein the cold start occurs when the engine is started and the engine coolant temperature is less than an operating temperature.

17. The method of claim 15, further comprising terminating the catalyst heat mode when a catalyst temperature is greater than or equal to a light-off temperature.

18. The method of claim 11, wherein the catalyst is at least one of an electrically-heated catalyst and a three-way catalyst.

19. The method of claim 11, wherein the lean value is equal to approximately 11.5 and the rich value is equal to approximately 16.

20. The method of claim 11, wherein the lean value is equal to approximately 13 and the rich value is equal to approximately 16.