System and method for reducing NOx emissions in an apparatus having a diesel engine

• US 20070062179A1
• Filed: 09/20/2005
• Published: 03/22/2007
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Leone, Thomas
• Granted Patent: US 7,832,197 B2
• Time in Patent Office: Days
• US Class Current: 60/285
• CPC Class Codes: F02B 2275/14 Direct injection into combustion chamber
• 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 13/0219 by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 13/0265 Negative valve overlap for temporarily storing residual gas in the cylinder
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 2200/0802 Temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/006 using internal EGR control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01
• CPC Class Codes: F02D 41/0245 by increasing temperature of the exhaust gas leaving the engine
• CPC Class Codes: F02D 41/0275 the exhaust gas treating apparatus being a NOx trap or adsorbent
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: F02D 41/3035 a mode being the premixed charge compression-ignition mode
• CPC Class Codes: F02M 26/01 Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In a mechanical apparatus having a diesel engine including a combustion chamber, the mechanical apparatus also having an aftertreatment device configured to treat emissions from the diesel engine, an intake valve for passing air into the combustion chamber, and an exhaust valve for passing exhaust out of the combustion chamber, a method of operating the engine, wherein the method includes performing at least one combustion in the combustion chamber at a first exhaust valve timing and a first intake valve closure timing; determining a temperature of the exhaust gas that enters the aftertreatment device; and if the temperature of the exhaust gas is equal to or below a preselected temperature threshold, then performing at least one combustion in the combustion chamber at a second, earlier exhaust valve closure timing and a second later intake valve opening timing to thereby increase the internal exhaust gas recirculation and the temperature of exhaust emitted by the diesel engine.

Claims

1. A method of controlling a diesel engine including a combustion chamber, the engine coupled to an aftertreatment device configured to treat emissions from the diesel engine, the cylinder having an intake valve for passing air into the combustion chamber, and an exhaust valve for passing exhaust out of the combustion chamber, comprising:

performing at least one combustion in the combustion chamber at a first exhaust valve closing timing and a first intake valve opening timing; and

when temperature of the exhaust gas is equal to or below a preselected temperature threshold, performing at least one combustion in the combustion chamber at a second, earlier exhaust valve closing timing and a second, later intake valve opening timing to thereby increase the internal exhaust gas recirculation and the temperature of exhaust emitted by the diesel engine.

2. The method of claim 1, wherein the aftertreatment device includes a NOx trap.

3. The method of claim 1, wherein performing at least one combustion in the combustion chamber at the second exhaust valve closing timing and the second intake valve opening includes advancing a rotation of a camshaft that opens the exhaust valve and retarding a rotation of a camshaft that opens the intake valve.

4. The method of claim 1, wherein exhaust valve and intake valve timing are controlled electronically.

5. The method of claim 1, wherein an amount of exhaust valve advancement and an amount of intake valve retard are equal.

6. The method of claim 1, wherein an amount of exhaust valve advancement and an amount of intake valve retard are different.

7. The method of claim 1, further comprising determining a temperature of the exhaust gas after performing at least one combustion at the second exhaust valve closing timing and second intake valve opening timing.

8. The method of claim 7, wherein the preselected temperature threshold is a first preselected temperature threshold, the method further comprising comparing the temperature of the exhaust gas determined after performing said at least one combustion to a second preselected temperature threshold, and if the temperature of the exhaust gas determined after performing said at least one combustion is greater than or equal to the second preselected temperature threshold, then performing another combustion at the first exhaust valve closing timing and the first intake valve opening timing.

9. The method of claim 7, wherein the first preselected temperature threshold and the second preselected temperature threshold are equal.

10. The method of claim 7, wherein the first preselected temperature threshold and the second preselected temperature threshold are different.

11. The method of claim 1 further comprising advancing injection timing if temperature of the exhaust gas is equal to or below said preselected temperature threshold.

19. The method of claim 1, wherein the advance of the third exhaust valve closing is less than the advance of the second exhaust valve closing.

12. A method of controlling a diesel engine including a combustion chamber, the engine coupled to an aftertreatment device configured to treat emissions from the diesel engine, the cylinder having an intake valve for passing air into the combustion chamber, and an exhaust valve for passing exhaust out of the combustion chamber, comprising:

performing at least one combustion in the combustion chamber at a first exhaust valve closing timing and a first intake valve opening timing;

if temperature of the exhaust gas is equal to or below a preselected temperature threshold, performing at least one combustion in the combustion chamber at a second, earlier exhaust valve closing timing and a second, later intake valve opening timing to thereby increase the internal exhaust gas recirculation and the temperature of exhaust emitted by the diesel engine.

if the external exhaust gas recirculation rate is below a preselected value, performing at least one combustion in the combustion chamber at a third earlier exhaust valve closing timing to thereby increase internal exhaust gas recirculation; and

13. The method of claim 12, wherein the aftertreatment device includes a NOx trap.

14. The method of claim 12, wherein performing at least one combustion in the combustion chamber at the second exhaust valve closing timing and the second intake valve opening includes advancing a rotation of a camshaft that opens the exhaust valve and retarding a rotation of a camshaft that opens the intake valve.

15. The method of claim 12, wherein performing at least one combustion in the combustion chamber at the third exhaust valve closing timing includes advancing a rotation of a camshaft that opens the exhaust valve.

16. The method of claim 12, wherein exhaust valve and intake valve timing are controlled electronically.

17. The method of claim 12, wherein an amount of exhaust valve advancement and an amount of intake valve retard are equal.

18. The method of claim 12, wherein an amount of exhaust valve advancement and an amount of intake valve retard are different.

20. A method of controlling a diesel engine including a combustion chamber, the engine coupled to an aftertreatment device configured to treat emissions from the diesel engine, the cylinder having an intake valve for passing air into the combustion chamber, and an exhaust valve for passing exhaust out of the combustion chamber, comprising:

advancing exhaust valve opening timing and exhaust valve closing timing and retarding intake valve opening timing and intake valve closing timing during a first exhaust temperature;

retarding exhaust valve opening timing and exhaust valve closing timing and advancing intake valve opening timing and intake valve closing timing during a second, higher, exhaust temperature;

advancing exhaust valve opening timing and exhaust valve closing timing and retarding intake valve opening timing and intake valve closing timing during a first external exhaust gas recirculation condition; and

retarding exhaust valve opening timing and exhaust valve closing timing and advancing intake valve opening timing and intake valve closing timing during a second, higher, external exhaust gas recirculation condition.