# US 8,769,935 B2 · System and method for monitoring reductant quality > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,769,935 B2 - Document ID: US8769935B2 - Status: Granted - Kind: B2 - Application number: 13/429,125 - Filed: 2012-03-23 - Published: 2012-08-02 - Granted: 2014-07-08 - Earliest claimed: 2007-01-31 - Assignees: Ford Global Technologies, LLC - Applicants: Furqan Zafar Shaikh; John Paul Bogema; Michiel J. Van Nieuwstadt; Scott Donald Cooper; Garry Anthony Zawacki; Jacobus Hendrik Visser; William Charles Ruona; Timothy Webb; Ed Kulik; David K. Chen - Inventors: Furqan Zafar Shaikh; John Paul Bogema; Michiel J. Van Nieuwstadt; Scott Donald Cooper; Garry Anthony Zawacki; Jacobus Hendrik Visser; William Charles Ruona; Timothy Webb; Ed Kulik; David K. Chen - Web page: https://patentgrep.com/patent/US8769935B2 ## CPC - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - F01N 9/00: Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) - F01N 2560/026: for measuring or detecting NOx - F01N 2570/145: Dinitrogen oxide - F01N 2610/1406: Storage means for substances, e.g. tanks or reservoirs - F01N 2610/146: Control thereof, e.g. control of injectors or injection valves - F01N 2900/12: said parameters being related to the vehicle exterior - F01N 2900/1814: Tank level - Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters - Y02C 20/10: of nitrous oxide (N2O) - Y02T 10/12: Improving ICE efficiencies - Y02T 10/40: Engine management systems - 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) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG] - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method of operating an internal combustion engine having a reductant delivery and storage system in an emission control system, comprising of correlating a change in a monitored operating condition with a refill event to determine whether a reductant-diluting substance has been added to the reductant storage system; and limiting vehicle operation based on the correlation. ## Claims ### Claim 1 A method of operating a system having an engine and engine fuel system, and a separate reductant delivery and storage system for an SCR catalyst, comprising: correlating a change in a monitored operating condition with a reductant storage refill event to determine a dilution of ammonia concentration from addition of a reductant-diluting substance to the reductant storage system, the correlation based on whether the change occurred within a time range from the refill event; and performing default action based on the correlation, said refill event identified based on factors comprising at least one of an angle of inclination of the reductant storage system or a road condition. ### Claim 2 (depends on 1) The method of claim 1, wherein said monitored operating condition is at least a NOx amount. ### Claim 3 (depends on 1) The method of claim 1, wherein said monitored operating condition is at least a reductant flow rate. ### Claim 4 (depends on 1) The method of claim 1, wherein said time range is a length of time to deplete and refill the SCR catalyst. ### Claim 5 A method of operating an engine having a reductant delivery and storage system in an emission control system, comprising: correlating a change in a monitored operating condition with a refill event to determine whether a reductant-diluting substance has been added to the reductant storage system, said refill event identified based on factors comprising at least an ambient temperature condition and a reductant storage system inclination angle; and limiting vehicle operation based on the correlation. ### Claim 6 (depends on 5) The method of claim 5, wherein said monitored operating condition is at least a NOx amount. ### Claim 7 (depends on 5) The method of claim 5, wherein said monitored operating condition is at least a reductant flow rate. ### Claim 8 (depends on 5) The method of claim 5, wherein the correlation is based on whether the change occurred within a time range from the refill event. ### Claim 9 (depends on 8) The method of claim 8, wherein said time range is a length of time to deplete and refill an SCR catalyst in an exhaust. ### Claim 10 In a vehicle comprising an internal combustion engine and an emission control system comprising an SCR catalyst, a reductant storage device separate from a fuel storage device, and a reductant delivery system, a method for monitoring reductant quality in the emission control system, the method comprising: sensing an operating condition of the emission control system; detecting a deviation from said operating condition; determining whether the deviation occurred after a refill event of the reductant storage device separate from the fuel storage device, said refill event identified based on factors comprising at least one of an angle of inclination of the reductant storage device or a road condition; and if the deviation occurred after the refill event, then determining that a change in reductant quality due to reductant dilution has occurred within a time by addition of a reductant-diluting substance to the reductant storage device separate from the fuel storage device, the reductant reducing NOx in the SCR catalyst. ### Claim 11 (depends on 10) The method of claim 10, wherein said operating condition is at least a concentration of nitrous oxide and said deviation is an increase in said concentration of nitrous oxide, said time being a length of time to deplete and refill the SCR catalyst. ### Claim 12 (depends on 10) The method of claim 10, wherein said operating condition is at least a reductant flow rate and said deviation is a reduction in said reductant flow rate. ### Claim 13 (depends on 10) The method of claim 10, wherein determining whether the deviation occurred after a refill event of the reductant storage device comprises detecting if a refill flag is set when the deviation occurred. ### Claim 14 (depends on 13) The method of claim 13, wherein said time is a length of time to deplete and refill the SCR catalyst.