# US 10,371,031 B2 · Methods and systems for introducing reductant into an exhaust passage > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,031 B2 - Document ID: US10371031B2 - Status: Granted - Kind: B2 - Application number: 15/387,366 - Filed: 2016-12-21 - Published: 2017-06-22 - Granted: 2019-08-06 - Earliest claimed: 2015-12-22 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Frederik De Smet; Monika Angst - Web page: https://patentgrep.com/patent/US10371031B2 ## CPC - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - F01N 3/0814: {combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts} - F01N 3/0842: {Nitrogen oxides} - F01N 3/103: {Oxidation catalysts for HC and CO only} - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 11/007: {the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus} - F01N 13/0093: {the purifying devices are of the same type} - F02M 26/06: Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor - F02M 26/15: in relation to engine exhaust purifying apparatus - F01N 2560/026: for measuring or detecting NOx - F01N 2610/02: the substance being ammonia or urea - F01N 2900/1616: NH3-slip from catalyst - 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 - 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) - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Methods and systems are provided for an exhaust passage having a plurality of catalysts. In one example, a method may include injecting reductant via one or more injectors of the exhaust passage and monitoring injection conditions by flowing exhaust gas to the engine. ## Claims ### Claim 1 A method comprising: flowing low-pressure exhaust gas to an engine while a first injector is injecting, where the first injector is positioned to inject into an exhaust passage upstream of a first selective catalytic reduction device for treating NOx and a low-pressure exhaust gas recirculation passage branches from the exhaust passage downstream of the first selective catalytic reduction device; sensing reductant slip through the first selective catalytic reduction device via an exhaust gas sensor located in the exhaust passage upstream of the first injector; and adjusting injection conditions in response to a comparison between a sensed NOx value and a threshold NOx value. ### Claim 2 (depends on 1) The method of claim 1, wherein the threshold NOx value is based on a sum of an expected engine output NOx and an expected NOx increase corresponding to the reductant slip. ### Claim 3 (depends on 1) The method of claim 1, wherein the adjusting includes decreasing an injection amount of the first injector in response to the comparison indicating the sensed NOx value being greater than the threshold NOx value. ### Claim 4 (depends on 3) The method of claim 3, wherein the adjusting further includes adjusting injection conditions of a second injector corresponding to a second selective catalytic reduction device for treating NOx, where the second injector is upstream of the second selective catalytic reduction device and downstream of the low-pressure exhaust gas recirculation passage. ### Claim 5 (depends on 4) The method of claim 4, wherein the adjusting in response to the comparison includes increasing an injection amount of the second injector when the sensed NOx value is greater than the threshold NOx value. ### Claim 6 (depends on 1) The method of claim 1, wherein flowing low-pressure exhaust gas is in response to an engine exhaust gas recirculation demand or the first injector injecting. ### Claim 7 A method comprising: injecting reductant into an exhaust passage via first and second injectors, where the first injector is upstream of a first selective catalytic reduction device for treating NOx and the second injector is upstream of a second selective catalytic reduction device for treating NOx, further comprising an exhaust gas recirculation passage coming off the exhaust passage between the first selective catalytic reduction device and the second injector; and injecting reductant via both injectors during a first condition, where a ratio between the injectors is adjusted responsive to sensing recirculated reductant slip coming around through an EGR passage, and where the sensing occurs at an exhaust gas sensor located in the exhaust passage upstream of the first injector. ### Claim 8 (depends on 7) The method of claim 7, wherein the first injector and the second injector inject a gaseous ammonia or a liquid ammonia solution. ### Claim 9 (depends on 7) The method of claim 7, wherein the first injector injects urea and the second injector injects fuel, further comprising a nitrogen oxide trap catalyst being located between the second injector and the second selective catalytic reduction device. ### Claim 10 (depends on 7) The method of claim 7, further comprising adjusting injection amounts of the first and second injectors, the adjusting being in response to a comparison between a NOx sensed by the exhaust gas sensor in the exhaust passage and a threshold value, the adjusting further comprising decreasing a first injector injection amount and increasing a second injector injection amount in response to the NOx sensed being greater than the threshold value. ### Claim 11 (depends on 7) The method of claim 7, wherein the first injector is configured to inject reductant into the exhaust passage directly upstream of the first selective catalytic reduction device located between the injector and the exhaust gas recirculation passage, and where the second injector is configured to inject reductant into the exhaust passage upstream of the second selective catalytic reduction device, and where the second injector is located between the exhaust gas recirculation passage and the second selective catalytic reduction device. ### Claim 12 (depends on 11) The method of claim 11, wherein the first injector and the second injector inject in response to one or more of a reductant store of the first selective catalytic reduction device being less than a first threshold store and a reductant store of the second selective catalytic reduction device being less than a second threshold store. ### Claim 13 (depends on 12) The method of claim 12, wherein injecting in response to the reductant store of the second selective catalytic reduction device being less than the second threshold store and a reductant volume in a second reservoir corresponding to the second injector is less than an injection amount determined for the second injector further includes dividing the injection amount between the first and second injectors based on a reductant slip through the first selective catalytic reduction device coming around the exhaust gas recirculation passage, and where the injection amount of the first injector is increased in response to a NOx sensed at the exhaust gas sensor being less than a threshold value.