Method and system for reducing engine exhaust emissions

Patent metadata

Field	Value
Publication number	US-2016305302-A1
Application number	US-201514689309-A
Country	US
Kind code	A1
Filing date	Apr 17, 2015
Priority date	Apr 17, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

Methods and systems are provided for addressing engine cold-start emissions while an exhaust catalyst is activated. In one example, a method for improving exhaust emissions may include flowing ionized air into an engine exhaust, downstream of an exhaust catalyst, to oxidize exhaust emissions left untreated by the catalyst. The approach reduces the PM load of the exhaust as well as of a downstream particulate matter filter.

First claim

1 . A method for an engine, comprising:
introducing ionized air downstream of an exhaust catalyst responsive to catalyst temperature.

2 . The method of claim 1 , further comprising, oxidizing organic matter downstream of the exhaust catalyst using the ionized air.

3 . The method of claim 2 , wherein the catalyst is an exhaust oxidation catalyst, and wherein the introducing includes initiating introduction of ionized air when a catalyst temperature is below a threshold, continuing to introduce the ionized air until the catalyst temperature is at the threshold, and discontinuing the introduction of ionized air when the catalyst temperature is above the threshold.

4 . The method of claim 3 , wherein the introducing includes operating an electric air pump and an ionizer so as to add a threshold portion of aircharge received at the catalyst with ionized air, the threshold portion based on the catalyst temperature relative to the threshold.

5 . The method of claim 3 , further comprising, adjusting one or more of an amount of ionized air introduced, a rate of introduction of the ionized air, and a duration of introduction of the ionized air based on the catalyst temperature relative to the threshold.

6 . The method of claim 2 , wherein the oxidizing includes oxidizing organic matter in a mixing chamber coupled downstream of the exhaust catalyst, and releasing the oxidized organic matter from the mixing chamber into an exhaust tailpipe.

7 . The method of claim 1 , wherein the introducing of ionized air is further based on an estimated exhaust particulate matter load.

8 . The method of claim 1 , further comprising, while introducing the ionized air, limiting rich engine operation to above a threshold air-fuel ratio.

9 . A method for a hybrid vehicle system, comprising:
in response to one or more of an exhaust catalyst temperature being below an activation threshold, and an exhaust particulate matter load being higher than a threshold load, operating an ionizer to introduce ionized air downstream of the exhaust catalyst.

10 . The method of claim 9 , wherein the exhaust particulate matter load is one of an estimated exhaust particulate matter load estimated by a soot sensor, an expected exhaust particulate matter load inferred based on engine operating conditions, and a soot load of a particulate filter coupled downstream of the exhaust catalyst.

11 . The method of claim 9 , further comprising, continuing operation of the ionizer until the exhaust catalyst temperature is at or above the activation threshold, or the exhaust particulate matter load is below the threshold load.

12 . The method of claim 9 , wherein the operating includes, enabling the ionizer and adjusting an output of an electric air pump coupled to the ionizer so as to add a threshold fraction of aircharge received downstream of the exhaust catalyst with ionized air.

13 . The method of claim 9 , further comprising, while introducing the ionized air, limiting an engine combustion air-fuel ratio to be at or above a threshold air-fuel ratio, the threshold air-fuel ratio based one of a duration and an amount or ionized air introduced downstream of the catalyst.

14 . The method of claim 9 , further comprising, in response to a request for rich engine operation for engine component protection, disabling operation of the ionizer.

15 . The method of claim 9 , further comprising, oxidizing exhaust organic matter, including exhaust particulate matter, in a mixing chamber coupled downstream of the exhaust catalyst, and releasing the oxidized organic matter and heat from the mixing chamber into an exhaust tailpipe.

16 . A hybrid vehicle system, comprising:
an engine including an intake and an exhaust, the exhaust including an oxidation catalyst; an electric air pump for flowing air into an ionizer; an ionizer for ionizing air into ionic air; an electric motor; vehicle wheels propelled via one or more of the engine and the electric motor; and a controller with computer-readable instructions stored on non-transitory memory for: during a first engine cold-start of a drive cycle, discontinuing vehicle propulsion via the motor while operating the engine with ignition timing retard to raise a temperature of the catalyst above a threshold temperature; and during a second, subsequent engine cold-start of the drive cycle, continuing vehicle propulsion via the motor while flowing ionized air into the engine exhaust, downstream of the exhaust catalyst, while operating the engine, until the temperature of the exhaust catalyst is above the threshold temperature.

17 . The system of claim 16 , wherein the first engine cold-start of the drive cycle is responsive to an initial drop in exhaust catalyst temperature during the vehicle propulsion via the motor, and wherein the second engine cold-start of the drive cycle is responsive to a subsequent drop in exhaust catalyst temperature while the vehicle is propelled via the motor.

18 . The system of claim 16 , wherein a drop in catalyst temperature during the first engine cold-start of the drive cycle is to a lower temperature than the drop in catalyst temperature during the second engine cold-start of the drive cycle.

19 . The system of claim 16 , wherein a particulate matter load of exhaust gas during the first engine cold-start of the drive cycle is a higher than the particulate matter load of exhaust gas during the second engine cold-start of the drive cycle.

20 . The system of claim 16 , wherein the controller includes instructions for flowing ionized air into the engine exhaust by operating the ionizer and adjusting an output of the electric air pump based on a difference between the temperature of the exhaust catalyst and the threshold temperature.

Assignees

• Ford Global Tech Llc

Inventors

• Martin Douglas Raymond
• Miller Kenneth James
• Van Nieuwstadt Michiel J
• Rollinger John Eric

Classifications

• B01D53/92

  of engine exhaust gases (exhaust {or silencing} apparatus {for internal combustion engines, machines or engines in general}, having means for purifying, {rendering innocuous} or otherwise treating exhaust gases F01N3/00) · CPC title

• B01D2251/11

  Air · CPC title

• B01D53/944

  Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts (three-way-catalysts [TWC] B01D53/9445) · CPC title

• B01D53/9418

  for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas · CPC title

• B01D2259/122

  Gaseous reactants · CPC title