# US 9,518,287 B2 · NOx control during engine idle-stop operations > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,287 B2 - Document ID: US9518287B2 - Status: Granted - Kind: B2 - Application number: 14/512,326 - Filed: 2014-10-10 - Published: 2015-01-29 - Granted: 2016-12-13 - Earliest claimed: 2012-08-02 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Joseph Robert Theis; James Michael Kerns; Michael James Uhrich; Giovanni Cavataio; Thomas G. Leone; Jeffrey Allen Doering; Todd Anthony Rumpsa - Web page: https://patentgrep.com/patent/US9518287B2 ## CPC - C12Q 1/6806: Preparing nucleic acids for analysis, e.g. for polymerase chain reaction [PCR] assay (C12Q1/6804 takes precedence) - F02D 41/0087: {Selective cylinder activation, i.e. partial cylinder operation (deceleration cut-off F02D41/123)} - F01N 13/0093: {the purifying devices are of the same type} - F01N 13/011: {having two or more purifying devices arranged in parallel} - F02D 41/027: {to purge or regenerate the exhaust gas treating apparatus} - F02D 41/042: {for stopping the engine} - F01N 3/101: {Three-way catalysts} - F01N 3/2066: {Selective catalytic reduction [SCR]} - F02D 41/0235: {in relation with the state of the exhaust gas treating apparatus (control of exhaust gas treating apparatus per se F01N)} - F02D 41/126: {transitional corrections at the end of the cut-off period} - F02N 11/0818: {Conditions for starting or stopping the engine or for deactivating the idle-start-stop mode} - Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters - Y02T 10/12: Improving ICE efficiencies - C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - F02N: STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Methods and systems are provided for improving engine exhaust emissions while enabling exhaust catalyst regeneration following an engine lean event. Prior to a VDE event, or prior to an engine idle-stop, ammonia is produced and stored on an exhaust underbody SCR catalyst. Then, during the engine restart after the VDE mode or the idle-stop, the stored ammonia is used to treat exhaust NOx species while an upstream exhaust underbody three-way catalyst is regenerated. ## Claims ### Claim 1 An engine method, comprising: during engine running, flowing exhaust through each of a first, second, and third close-coupled three-way catalyst to store exhaust ammonia on the first catalyst, the second catalyst located downstream of, and the third catalyst located upstream of, the first catalyst; selectively deactivating the engine during an idle-stop; and during an engine restart from idle-stop, adjusting regeneration of the third catalyst based on an ammonia content of the first catalyst. ### Claim 2 (depends on 1) The method of claim 1, wherein the first catalyst is an SCR catalyst and the second and third catalysts are three-way catalysts, the method further comprising, after regenerating the third catalyst, in response to a high load engine operation, adjusting regeneration of the second catalyst. ### Claim 3 (depends on 2) The method of claim 2, wherein regenerating the third catalyst includes, during the engine restart, adjusting a fuel injection to the engine to provide an exhaust air-to-fuel ratio that is richer than stoichiometry to regenerate the third catalyst. ### Claim 4 (depends on 3) The method of claim 3, wherein adjusting the regeneration includes, as the ammonia content of the first catalyst increases above a threshold, reducing a degree of richness of the regenerating fuel injection. ### Claim 5 (depends on 3) The method of claim 3, wherein the adjusting further includes, as the ammonia content of the first catalyst increases above a threshold, reducing a duration of regenerating the third catalyst with the rich fuel injection. ### Claim 6 (depends on 3) The method of claim 3, wherein adjusting the regeneration includes, as the ammonia content of the first catalyst decreases below a threshold, increasing a degree of richness of the regenerating fuel injection. ### Claim 7 (depends on 1) The method of claim 1, wherein the first catalyst and the second catalyst are integrated with face-sharing contact in an emission control device coupled to an engine exhaust manifold. ### Claim 8 (depends on 1) The method of claim 1, wherein the ammonia content of the first catalyst is based at least on a duration of an immediately preceding idle-stop. ### Claim 9 (depends on 1) The method of claim 1, wherein the engine is coupled to a vehicle, and wherein the ammonia content of the first catalyst is based at least on a number of engine idle-stop events estimated over a duration of vehicle operation. ### Claim 10 An engine method comprising: during a first engine restart from idle-stop, when an ammonia content of a first exhaust SCR catalyst is higher than a threshold, injecting fuel with a first, lower rich bias to regenerate each of a second and third close-coupled three-way exhaust catalyst, the second exhaust catalyst positioned downstream of the first catalyst, the third exhaust catalyst positioned upstream of the first catalyst; and during a second engine restart from idle-stop, when the ammonia content of the first exhaust catalyst is lower than the threshold, injecting fuel with a second, higher rich bias to regenerate the second and third exhaust catalysts. ### Claim 11 (depends on 10) The method of claim 10, wherein during each of the first and second engine restarts, the ammonia content of the first catalyst is based at least on a duration of an immediately preceding idle-stop. ### Claim 12 (depends on 11) The method of claim 11, wherein during each of the first and second engine restarts, the ammonia content of the first catalyst is further based on one or more engine operating conditions estimated during engine running prior to the idle-stop, the one or more conditions including exhaust gas temperature, exhaust flow rate, engine speed, engine load, and exhaust air-to-fuel ratio. ### Claim 13 (depends on 10) The method of claim 10, wherein during each of the first and second engine restarts, exhaust gas is flowed through the third catalyst followed by the first catalyst and then the second catalyst before venting to atmosphere. ### Claim 14 (depends on 10) The method of claim 10, wherein the first catalyst and the second catalyst are integrated in an emission control device coupled to an exhaust manifold of the engine. ### Claim 15 An engine system, comprising: an engine that is selectively deactivatable responsive to idle-stop conditions; an emission control device coupled to an engine exhaust manifold, the device including a first, upstream SCR catalyst in face-sharing contact with a second, downstream catalyst; a third close-coupled three-way exhaust catalyst positioned upstream of the emission control device; and a control system with non-transitory computer readable instructions for, during an engine restart from idle-stop, adjusting fuel injection to be richer than stoichiometry to regenerate the third catalyst, a degree of richness adjusted based on an ammonia content of the first catalyst. ### Claim 16 (depends on 15) The system of claim 15, wherein the ammonia content of the first catalyst at the engine restart is based on the idle-stop, the ammonia content of the first catalyst at engine restart decreased as a duration of the idle-stop increases. ### Claim 17 (depends on 16) The system of claim 16, wherein the adjusting includes, as the ammonia content of the first catalyst decreases, increasing a degree of richness of the fuel injection. ### Claim 18 (depends on 16) The system of claim 16, wherein the ammonia content of the first catalyst at engine restart is further based on a temperature of the emission control device. ### Claim 19 (depends on 15) The system of claim 15, wherein the first catalyst has a higher ammonia storage content than the second catalyst. ### Claim 20 (depends on 15) The system of claim 15, wherein the control system includes further instructions for, prior to the idle-stop, adjusting fuel injection to the engine to be richer than stoichiometry, a degree of richness adjusted responsive to the ammonia content of the first catalyst to maintain the ammonia content of the first catalyst above a threshold amount.