Method and system for exhaust gas recirculation and heat recovery

Patent metadata

Field	Value
Publication number	US-2018355809-A1
Application number	US-201816106875-A
Country	US
Kind code	A1
Filing date	Aug 21, 2018
Priority date	Dec 1, 2016
Publication date	Dec 13, 2018
Grant date	—

Abstract

Methods and systems are provided for a single heat exchanger coupled to a main exhaust passage upstream of one or more exhaust catalysts or in between two exhaust catalysts for exhaust heat recovery and exhaust gas recirculation (EGR) cooling. In one example, in the pre-catalyst configuration of the heat exchanger, during exhaust heat recovery, a portion of exhaust may be routed via the heat exchanger while the remaining portion of exhaust may be routed directly to the exhaust catalysts, and fueling may be adjusted on a per-cylinder basis to maintain a target exhaust air-fuel-ratio at the exhaust catalysts.

First claim

1 - 12 . (canceled)

13 . A method, comprising:
during engine cold-start conditions, actuating a diverter valve coupled to a bypass passage to a fully closed position and closing an EGR valve to enable exhaust flow from downstream of a first exhaust catalyst to upstream of a second exhaust catalyst via a main exhaust passage; after activation of at least the second exhaust catalyst, actuating the diverter valve to a partially open position and closing the EGR valve to enable a first portion of exhaust to flow from downstream of the first exhaust catalyst to upstream of the second exhaust catalyst via a heat exchanger housed in the bypass passage, and a second, remaining portion of exhaust to flow from downstream of the first exhaust catalyst to upstream of the second exhaust catalyst via the main exhaust passage, the first portion and the second portion of exhaust combining upstream of the second exhaust catalyst and then flowing through the second exhaust catalyst.

14 . The method of claim 13 , wherein a ratio of the first portion to the second portion is based on a temperature of the second exhaust catalyst relative to an activation temperature of the second exhaust catalyst and an opening of the diverter valve is adjusted based on the first portion, the opening increased as the first portion is increased and wherein flowing exhaust via the heat exchanger includes transferring exhaust heat to a coolant circulating through the heat exchanger, and then transferring heat from the coolant to an engine block based on engine heating demand.

15 . The method of claim 14 , wherein the first portion is decreased and the second portion is correspondingly increased as the temperature of the second exhaust catalyst decreases to below the activation temperature.

16 . The method of claim 13 , further comprising, in response to a demand for exhaust gas recirculation, actuating the diverter valve to the fully closed position and opening the EGR valve to enable a third portion of exhaust to flow from downstream of the first exhaust catalyst to an engine intake via the heat exchanger and a fourth, remaining portion of exhaust to flow from downstream of the first exhaust catalyst to upstream of the second exhaust catalyst via the main exhaust passage, the third portion adjusted with respect to the fourth portion based on EGR demand, wherein the third portion is increased as the EGR demand increases.

17 . The method of claim 13 , further comprising, in response to each of a higher than threshold engine load and a higher than threshold engine temperature, actuating the diverter valve to the fully closed position and closing the EGR valve to enable exhaust flow from downstream of the first exhaust catalyst to upstream of the second exhaust catalyst via the main exhaust passage bypassing the heat exchanger.

18 - 20 . (canceled)

Assignees

• Ford Global Tech Llc

Inventors

• Uhrich Michael James
• Styles Daniel Joseph
• Bevan Karen Evelyn
• Schwartz William Samuel
• Baker Chad Allan

Classifications

• F02D2200/0802

  Temperature of the exhaust gas treatment apparatus · CPC title

• F02M2026/004

  EGR valve controlled by a temperature signal or an air/fuel ratio (lambda) signal · CPC title

• F01N13/008

  Mounting or arrangement of exhaust sensors in or on exhaust apparatus (sensor arrangements for engine control F02D41/1439) · CPC title

• F02D41/0085

  Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio · CPC title

• F02D41/0082

  per groups or banks (F02D41/0087 takes precedence) · CPC title