# US 8,273,315 B2 · Engine emission control system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,273,315 B2 - Document ID: US8273315B2 - Status: Granted - Kind: B2 - Application number: 12/853,075 - Filed: 2010-08-09 - Published: 2011-07-07 - Granted: 2012-09-25 - Earliest claimed: 2010-08-09 - Assignees: Ford Global Technologies, LLC - Inventors: Jeong Yeol Kim; Giovanni Cavataio - Web page: https://patentgrep.com/patent/US8273315B2 ## CPC - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 13/009: {having two or more separate purifying devices arranged in series} - F01N 2610/02: the substance being ammonia or urea - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Systems and methods are provided for reducing exhaust NOx species using a monolith substrate having a plurality of channels configured with radially varying cell density. An injector injects reductant into the substrate unobstructedly, without use of a mixer. In some embodiments, a twist angle of the channels is based on a distance from an inlet of the substrate and varies exponentially as a function of the distance. ## Claims ### Claim 1 A method of operating an emission control system coupled to an exhaust passage of an engine, comprising: injecting an amount of reductant upstream of a first monolithic cylindrical substrate having a plurality of channels of radially varying cell density, the radial variation including inner channels with a higher cell density and outer channels with a lower cell density, the injected amount of reductant flowing unobstructedly from an injector into the first substrate without use of a mixer; flowing exhaust gas through the first substrate to mix the exhaust gas with the injected reductant; and flowing the mixed exhaust gas over an SCR catalytic washcoat to catalytically convert a component of the mixed exhaust gas, wherein the channels are along a length of the first substrate, and wherein the channels are rotated progressively along a lateral axis along the length of the first substrate, a twist angle of the rotation varying exponentially as a function of a distance from an inlet of the first substrate. ### Claim 2 (depends on 1) The method of claim 1, wherein in addition to the SCR catalytic washcoat over which the mixed exhaust gas flows, another SCR catalytic washcoat is included on the first substrate. ### Claim 3 (depends on 2) The method of claim 2, wherein flowing the mixed exhaust gas over the SCR catalytic washcoat includes flowing the mixed exhaust gas through a second substrate positioned downstream of the first substrate, the SCR catalytic washcoat included on the second substrate. ### Claim 4 An emission control system of an engine exhaust passage, comprising: a monolithic-substrate having channels of varying cell density extending from an inlet end to an outlet end of the monolithic-substrate with a channel twist angle varying exponentially as a function of monolithic-substrate length; a downstream-substrate; an upstream injector to inject reductant to flow unobstructedly to the monolithic-substrate without use of a mixer via an upstream reductant injector; and an SCR catalytic washcoat on the monolithic-substrate or on the downstream-substrate. ### Claim 5 (depends on 4) The system of claim 4, wherein the catalytic washcoat includes zeolites. ### Claim 6 (depends on 4) The system of claim 4, wherein the monolithic-substrate is cylindrical and wherein the cell density of the channels varies radially with inner channels having a higher cell density and outer channels having a lower cell density. ### Claim 7 (depends on 6) The system of claim 6, wherein the channels are rectangular in cross-section. ### Claim 8 (depends on 7) The system of claim 7, wherein at least some of the channels are plugged. ### Claim 9 (depends on 8) The system of claim 8, wherein the downstream-substrate has a plurality of channels, and wherein an SCR catalytic washcoat is positioned on the downstream-substrate, a cell density of the channels of the downstream-substrate different from the cell density of the channels of the monolithic-substrate. ### Claim 10 (depends on 4) The system of claim 4, wherein the reductant is urea or ammonia. ### Claim 11 (depends on 4) The system of claim 4, wherein the monolithic-substrate has a lower thermal mass than the downstream-substrate. ### Claim 12 An emission control system coupled to an exhaust passage of an engine, comprising: a monolithic upstream substrate having a plurality of channels of varying cell density, the channels formed within the upstream substrate and having a length extending between an inlet end of the upstream substrate and an outlet end of the upstream substrate, the cell density varying radially through the upstream substrate with a higher cell density at a center of the upstream substrate and a lower cell density at a periphery of the upstream substrate, the channels twisted along the length of the channels, where a twist angle of the channels is based on a distance from the inlet of the upstream substrate and varies exponentially as a function of the distance, and where a position of a selected channel at the inlet end is twisted with respect to a position of the selected channel at the outlet end; a reductant injector positioned upstream of the upstream substrate for injecting reductant that flows unobstructedly from the injector to an inlet of the upstream substrate without use of a mixer; a downstream substrate having a plurality of channels of uniform cell density; and an SCR catalytic washcoat coated on the downstream substrate and the upstream substrate. ### Claim 13 (depends on 12) The system of claim 12, wherein the upstream substrate is cylindrical and a cross section of each channel is rectangular. ### Claim 14 (depends on 13) The system of claim 13, wherein a first end of a channel at the inlet of the upstream substrate is twisted by an angle from a second end of the channel at an outlet of the upstream substrate, the angle measured along a lateral axis of the upstream substrate.