# US 8,769,929 B2 · Exhaust system with a NOx sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,769,929 B2 - Document ID: US8769929B2 - Status: Granted - Kind: B2 - Application number: 13/603,273 - Filed: 2012-09-04 - Published: 2012-12-27 - Granted: 2014-07-08 - Earliest claimed: 2009-04-14 - Assignees: Ford Global Technologies, LLC - Applicants: David Charles Weber - Inventors: David Charles Weber - Web page: https://patentgrep.com/patent/US8769929B2 ## CPC - F01N 3/225: {Electric control of additional air supply} - B01D 53/30: Controlling by gas-analysis apparatus (regulating non electrical variables in general G05D) - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - F01N 3/22: Control of additional air supply only, e.g. using by-passes or variable air pump drives - F01N 3/30: Arrangements for supply of additional air (control, e.g. using by-passes or variable air pump drives, F01N3/22) - B01D 2251/2067: Urea - B01D 2257/404: Nitrogen oxides other than dinitrogen oxide - B01D 2258/01: Engine exhaust gases - 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 2560/025: for measuring or detecting O2, e.g. lambda sensors - F01N 2560/026: for measuring or detecting NOx - F01N 2900/1402: Exhaust gas composition - 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) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Various systems and methods are described for controlling a NOx sensor coupled to an engine exhaust system in a motor vehicle. One example method comprises generating an offset of the sensor based on an ambient air flow drawn into the exhaust system, the ambient air flow having circumvented cylinders of the engine, and adjusting an output of the sensor based on the generated offset. ## Claims ### Claim 1 An engine control method, comprising: before an engine start, exposing an exhaust gas sensor having a heater coupled in an engine exhaust system to ambient air both upstream and downstream of the sensor; upon the engine start, activating the sensor heater to heat the sensor even if temperature of combusted exhaust gas from the engine start is below a dew point temperature of the combusted exhaust gas while maintaining exposure of the sensor to ambient air both upstream and downstream of the sensor, including exposing the sensor to ram air circumventing the engine. ### Claim 2 (depends on 1) The method of claim 1 wherein the sensor is an O2 sensor. ### Claim 3 (depends on 1) The method of claim 1 wherein the sensor is a NOx sensor, and wherein the exposing includes exposing the sensor to the ram air via a valved bypass that leads to ram air without passing through cylinders of the engine, and exposing the sensor to ambient air downstream of the sensor via a tailpipe, where the valved bypass directs combusted exhaust gas from the engine start to bypass the sensor while the heater is activated until the exhaust gas dew point is above a threshold temperature. ### Claim 4 (depends on 3) The method of claim 3, further comprising: generating an offset of the sensor after a delay from switching from combusted exhaust gas to ram air flowing past the sensor, the delay being decreased with increased speed of a vehicle driven by the engine; adjusting an output of the sensor based on the sensor offset; and adjusting urea injection based on the adjusted sensor output. ### Claim 5 (depends on 3) The method of claim 3 further comprising, once the exhaust gas dew point is above the threshold temperature, controlling the valved bypass to expose the sensor to combusted exhaust gas from the engine while not exposing the sensor to the ram air. ### Claim 6 (depends on 5) The method of claim 5 further comprising: while the sensor is exposed to the ram air, identifying an ambient NOx amount based on output from the NOx sensor; and while the sensor is exposed to the combusted exhaust gas, identifying an exhaust NOx amount based on output from the NOx sensor. ### Claim 7 (depends on 6) The method of claim 6 wherein the ambient NOx amount is an offset of the NOx sensor, and wherein the exhaust NOx amount is based on the sensor offset. ### Claim 8 An engine control method, comprising: before engine start, exposing an exhaust NOx sensor having a heater to ambient air both upstream and downstream of the sensor; upon engine start, activating the heater to heat the sensor even if combusted engine exhaust gas temperature is below an exhaust dew point, while maintaining exposure of the sensor to ambient air both upstream and downstream of the sensor including exposing the sensor to ram air circumventing the engine; and adjusting urea injection responsive to the sensor. ### Claim 9 An engine control method, comprising: before engine start, exposing an exhaust NOx sensor having a heater to ambient air both upstream and downstream of the sensor; upon engine start, activating the heater to heat the sensor even if combusted engine exhaust gas temperature is below an exhaust dew point, while maintaining exposure of the sensor to ambient air both upstream and downstream of the sensor, once the exhaust gas dew point is above a threshold temperature, exposing the sensor to combusted exhaust gas from the engine and not exposing the sensor to ambient air upstream of the sensor; and adjusting urea injection responsive to the sensor.