SYSTEM AND METHOD FOR REDUCING NOx EMISSIONS AFTER FUEL CUT-OFF EVENTS

• US 20060021326A1
• Filed: 07/27/2004
• Published: 02/02/2006
• Est. Priority Date: 07/27/2004
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Midlam-Mohler, Shawn
• Granted Patent: US 7,051,514 B2
• Time in Patent Office: Days
• US Class Current: 60/278
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: F01N 2570/14 Nitrogen oxides
• CPC Class Codes: F01N 3/20 specially adapted for catalytic conversion F01N3/22 takes precedence; Methods of operation or control of catalytic converters
• CPC Class Codes: F02D 17/04 rendering engines inoperative or idling, e.g. caused by abnormal conditions dependent on lubricating conditions F01M1/22; dependent on cooling F01P5/14
• CPC Class Codes: F02D 41/0055 Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/126 transitional corrections at the end of the cut-off period
• CPC Class Codes: F02M 25/08 adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method of controlling exhaust emission oxides of nitrogen (NOx) from an internal combustion engine (ICE) includes the steps of determining when an engine speed is below a first predetermined level, and controlling an oxygen displacement valve (ODV) such that at least a portion of exhaust gas generated by the ICE is directed into an intake air flow of the ICE.

Claims

1. A method of controlling exhaust emission oxides of nitrogen (NOx) from an internal combustion engine (ICE), the method comprising:

determining when an engine speed is below a first predetermined level; and

controlling an oxygen displacement valve (ODV) such that at least a portion of exhaust gas generated by the ICE is directed into an intake air flow of the ICE.

2. The method set forth in claim 1 wherein the method is performed during a restart operation of a hybrid electric vehicle (HEV).

3. The method set forth in claim 1 wherein the method is performed during a deceleration operation of a conventional powertrain vehicle.

4. The method set forth in claim 1 further comprising fully closing an engine throttle.

5. The method set forth in claim 1 further comprising providing a rich air to fuel ratio (AFR) to the ICE for a first predetermined period of time.

6. The method set forth in claim 5 further comprising stopping delivery of fuel to the engine.

7. The method set forth in claim 1 further comprising controlling the ODV valve such that no exhaust gas is directed into the intake air flow when a decision is made to restart the engine.

8. The method set forth in claim 7 further comprising spinning up the engine up to a starting speed.

9. The method set forth in claim 8 further comprising providing a rich AFR to the engine for a second predetermined period of time.

10. The method set forth in claim 9 wherein the rich AFR is provided by controlling an evaporative control valve such that at least a portion of fuel evaporative vapors are directed to the intake air flow.

11. The method set forth in claim 7 further comprising opening a throttle.

12. A system for controlling exhaust emission oxides of nitrogen (NOx) from an internal combustion engine (ICE), the system comprising:

sensors for determining operating conditions of the ICE; and

a controller for determining when an engine speed is below a first predetermined level, and controlling an oxygen displacement valve (ODV) such that at least a portion of exhaust gas generated by the ICE is directed into an intake air flow of the ICE.

13. The system set forth in claim 12 wherein the ODV is controlled during a restart operation of a hybrid electric vehicle (HEV).

14. The system set forth in claim 12 wherein the ODV is controlled during a deceleration operation of a conventional powertrain vehicle.

15. The system set forth in claim 12 wherein the controller further fully closes an engine throttle.

16. The system set forth in claim 12 wherein the controller further provides a rich air to fuel ratio (AFR) to the ICE for a first predetermined period of time.

17. The system set forth in claim 16 wherein the rich AFR is provided by controlling an evaporative control valve such that at least a portion of fuel evaporative vapors are directed to the intake air flow.

18. The system set forth in claim 16 wherein the controller stops delivery of fuel to the engine.

19. The system set forth in claim 12 wherein the controller operates the ODV valve such that no exhaust gas is directed into the intake air flow when a decision is made to restart the engine.

20. The system set forth in claim 19 wherein the controller controls spinning up the engine up to a starting speed.

21. The system set forth in claim 20 wherein the controller provides a rich AFR to the engine for a second predetermined period of time.

22. The system set forth in claim 19 wherein the controller opens a throttle.

23. A method of controlling exhaust emission oxides of nitrogen (NOx) from a variable valve internal combustion engine (ICE), the method comprising:

determining when an engine speed is below a first predetermined level; and

controlling the variable valves such that at least a portion of exhaust gas generated by the ICE is directed into an intake air flow of the ICE.

24. The method set forth in claim 23 further including the step of controlling the variable valves such that no exhaust gas is directed into the intake air flow when a decision is made to restart the ICE.