Systems and methods for a split exhaust engine system

Patent metadata

Field	Value
Publication number	US-11085385-B2
Application number	US-201816204604-A
Country	US
Kind code	B2
Filing date	Nov 29, 2018
Priority date	Dec 16, 2016
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, an air-fuel control method for the engine system may include flowing air from the intake manifold through a plurality of engine cylinders to a junction of the exhaust passage and a bypass passage in response to a condition, the junction positioned along the exhaust passage between first and second emission control devices. The method may further include flowing exhaust gas to the first emission control device while flowing the air to the junction.

First claim

The invention claimed is:

1. An engine operating method, comprising:
flowing air from an intake manifold of an engine through a plurality of engine cylinders, and via a first set of cylinder exhaust valves exclusively coupled to a scavenge exhaust manifold, further flowing the air through a bypass passage, through a junction of an exhaust passage and the bypass passage, and then into the exhaust passage in response to a condition, the junction positioned along the exhaust passage between a first emission control device and a second emission control device, where both the first emission control device and the second emission control device are positioned in the exhaust passage, the exhaust passage coupled to a blowdown exhaust manifold and the bypass passage coupled between the scavenge exhaust manifold and the exhaust passage, between the first emission control device and the second emission control device; and
flowing exhaust gas from a second set of cylinder exhaust valves exclusively coupled to the blowdown exhaust manifold to the first emission control device, via the exhaust passage, while flowing the air to the junction, where flowing air from the intake manifold to the junction includes increasing an amount of opening of a first valve disposed in the bypass passage while increasing an amount of overlap between a first set of intake valves and the second set of exhaust valves,
where the condition includes an engine intake manifold pressure being greater than a pressure at an inlet of the second emission control device.

2. The method of claim 1 , where the exhaust passage includes a turbocharger turbine positioned upstream of the first emission control device.

3. The method of claim 1 , where the exhaust gas is a rich exhaust gas mixture that does not include air that has not participated in combustion in the plurality of engine cylinders, and where the air does not participate in combustion within the plurality of engine cylinders.

4. The method of claim 1 , where flowing air from the intake manifold to the junction further includes decreasing an amount of opening of a second valve disposed in an exhaust gas recirculation passage, the exhaust gas recirculation passage coupled between and to each of the scavenge exhaust manifold and an intake passage, the intake passage coupled to the intake manifold.

5. The method of claim 1 , further comprising providing a stoichiometric air-fuel gas mixture at the junction.

6. An engine operating method, comprising:
flowing exhaust from a first exhaust manifold to a first catalyst and a second catalyst, the first exhaust manifold receiving exhaust gas exclusively via a first set of exhaust valves, the second catalyst arranged downstream of the first catalyst in an exhaust passage; and
while flowing the exhaust gas, increasing an amount of overlap between a first set of intake valves and a set of second exhaust valves and increasing an amount of opening of a valve disposed in a bypass passage to flow intake blowthrough air to the second catalyst without flowing intake blowthrough air to the first catalyst via a second exhaust manifold receiving gas exclusively via the set of second exhaust valves in response to an engine intake manifold pressure condition, the intake blowthrough air flowed through a junction of the bypass passage and the exhaust passage before being flowed into the exhaust passage, the first catalyst and the second catalyst both being positioned in the exhaust passage, where the junction is between the first catalyst and the second catalyst such that the bypass passage is coupled between and to each of the second exhaust manifold and the exhaust passage, between the first catalyst and the second catalyst,
where the engine intake manifold pressure condition includes an engine intake manifold pressure being greater than a pressure at an inlet of the second catalyst.

7. The method of claim 6 , further comprising providing a stoichiometric air-fuel gas mixture in between the first catalyst and the second catalyst and where the exhaust passage includes a turbocharger turbine disposed upstream of the first catalyst.

8. The method of claim 7 , further comprising, while flowing the exhaust gas, increasing the amount of overlap and increasing the amount of opening of the valve, decreasing an amount of opening of an exhaust gas recirculation valve disposed in a recirculation passage coupled between the second exhaust manifold and an intake passage of an engine, upstream of a turbocharger compressor.

9. An engine operating method, comprising:
flowing blowdown gas without blowthrough air from a cylinder of an engine to a first exhaust emissions device and a second exhaust emissions device via a blowdown exhaust valve and a blowdown manifold coupled to the blowdown exhaust valve during a cycle of the cylinder, the second exhaust emissions device downstream of the first exhaust emissions device; and
flowing an amount of blowthrough air from the cylinder to the second exhaust emissions device and not the first exhaust emissions device via a scavenge exhaust valve and scavenge manifold coupled to the scavenge exhaust valve during the cycle, where flowing the blowthrough air includes opening a valve positioned along a bypass passage between the scavenge manifold and an inlet of the second exhaust emissions device in response to a request to regenerate the second exhaust emissions device and an engine intake manifold pressure condition, and flowing the blowthrough air to a junction of an exhaust passage and the bypass passage, the junction positioned along the exhaust passage between first and second exhaust emissions control devices, where the blowthrough air is flowed through the junction before being flowed into the exhaust passage, where both the first exhaust emissions control device and the second exhaust emissions device are positioned in the exhaust passage;
where the blowdown manifold is a first exhaust manifold in fluidic communication with a plurality of engine cylinders and a turbocharger turbine;
where the scavenge manifold is a second exhaust manifold in direct fluidic communication with the plurality of engine cylinders and an inlet of the second exhaust emissions device; and
adjusting an amount of overlap between opening of the scavenge exhaust valve and opening of an intake valve of the cylinder to adjust the amount of blowthrough air in response to an air-fuel ratio of gases in the scavenge manifold,
where the engine intake manifold pressure condition includes the engine intake manifold pressure being greater than a pressure at the inlet of the second exhaust emissions device.

10. The method of claim 9 , where the blowthrough air is air passing through the cylinder without participating in a combustion event and where the blowdown gas is blowdown exhaust gas that participated in the combustion event.

11. The method of claim 9 , further comprising flowing exhaust gas and blowthrough air to an intake manifold of an engine via the scavenge manifold while flowing blowthrough air from the cylinder to the second exhaust emissions device via the scavenge manifold.

12. The method of claim 9 , further comprising adjusting an amount of blowthrough air from the cylinder to the second exhaust emissions device via adjusting the valve positioned along the bypass passage between the scavenge manifold and the inlet of the second exhaust emissions device.

13. The method of claim 12 , further comprising adjusting the amount of blowthrough air in response to an output of an oxygen sensor disposed in the scavenge manifold.

14. The method of claim 9 , further comprising opening the valve in response to flo

Assignees

• Ford Global Tech Llc

Inventors

• Ulrey Joseph Norman
• Lewis Donald

Classifications

• F02M35/10222

  Exhaust gas recirculation [EGR]; Positive crankcase ventilation [PCV]; Additional air admission, lubricant or fuel vapour admission · CPC title

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02D41/0007

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02D41/005

  according to engine operating conditions · CPC title