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How well can mPEMS measure gas phase motor vehicle exhaust emissions?

Ford Motor Company-Diep Vu, Joseph Szente, Michael Loos, Matti Maricq
  • Technical Paper
  • 2020-01-0369
To be published on 2020-04-14 by SAE International in United States
“Real world emissions” is an emerging area of focus in motor vehicle related air quality. These emissions are commonly recorded using portable emissions measurement systems (PEMS) designed for regulatory application, which are large, complex and costly. Miniature PEMS (mPEMS) is a developing technology that can significantly simplify on-board emissions measurement and potentially promote widespread use. Whereas full PEMS use analyzers to record NOx, CO, and HCs similar to those in emissions laboratories, mPEMS tend to use electrochemical sensors and compact spectroscopic detectors for their small size and low cost. The present work evaluates this approach by comparing measurements of NOx, CO, CO2 and HC emissions from five commercial mPEMS to both laboratory and full regulatory PEMS measurements. It further examines the use of vehicle on-board diagnostics data to calculate exhaust flow, as an alternative to on-vehicle exhaust flow measurement. The evaluations include two vehicle types, gasoline direct injection and diesel, and employ the US EPA and Worldwide Harmonized Light duty drive cycles. The results show that two classes of electrochemical NOx sensors are capable of…
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Using Transmission Data to Isolate Individual Losses in Coastdown Road Load Coefficients

US Environmental Protection Agency-Andrew Moskalik
  • Technical Paper
  • 2020-01-1064
To be published on 2020-04-14 by SAE International in United States
As part of the U.S. Environmental Protection Agency’s continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, multiple transmissions have been benchmarked to determine their efficiency during operation. The benchmarking included a modified “coastdown test,” with the transmission on an engine dynamometer, to measure the transmission output drag as a function of speed while in neutral. The transmission drag data can be represented in quadratic form, similar to that used for vehicle coastdown test results, as F0 + F1V + F2V2, where V is the vehicle velocity. When evaluating the transmission test data, the relationships among the three coefficients found to be highly predictable, and in some cases the magnitude of the coefficients were quite large. Additionally, for some tested transmissions the deviation between the quadratic regression and the measured drag at individual velocities can be significant. To evaluate the effect of transmission losses in vehicle coastdown tests, the coastdown and dynamometer coefficients were pulled from the EPA’s published “Data on Cars used for Testing Fuel Economy” for an entire…
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Analysis of Drivability Influence on Tailpipe Emissions by Means of Engine-in-the-Loop Test Benches

FEV Europe GmbH-Stefan Tegelkamp, Michael Görgen, Martin Nijs, Johannes Scharf
RWTH Aachen University-Christian Heusch, Daniel Guse, Frank Dorscheidt, Johannes Claßen, Timm Fahrbach, Stefan Pischinger
  • Technical Paper
  • 2020-01-0373
To be published on 2020-04-14 by SAE International in United States
Due to increasing environmental awareness, standards for pollutant and CO2 emission legislations are getting stricter in most markets around the world. In important markets such as Europe, also the emissions during driving on real roads, the so called “Real Driving Emissions” (RDE), are now a part of the type approval process for passenger cars. In addition to the hybridization and electrification of vehicles, the complexity and degrees of freedom of conventional powertrains with internal combustion engines are continuing to increase in order to comply with stricter exhaust emission standards. Besides the different requirements placed on vehicle emissions, the drivability capabilities of passenger vehicles desired by the costumers, varies within markets. Since the interactions between different hardware and software systems of the powertrain strongly influence the drivability characteristics of a vehicle, a high degree of maturity of prototype vehicles is required to execute drivability calibration tasks. Hence, these tasks are generally conducted in late phases of the vehicle development process. The assessment of the influence of drivability calibration on the vehicle’s tailpipe emissions is complex. Since…
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Benchmarking a 2018 Toyota Camry UB80E Eight-Speed Automatic Transmission

US Environmental Protection Agency-Andrew Moskalik, Mark Stuhldreher, John Kargul
  • Technical Paper
  • 2020-01-1286
To be published on 2020-04-14 by SAE International in United States
As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry UB80E front wheel drive 8-speed automatic transmission was benchmarked to determine the losses in operation. The transmission was installed in an engine dynamometer test cell equipped with the 4-cylinder engine from the 2018 Toyota Camry and inline torque transducers to measure transmission loads. A series of tests were conducted to determine the losses associated with the transmission operation, including transmission torque loss in each gear, torque converter K factor, neutral “coastdown” losses, idle torque, and oil temperature effects. The transmission benchmark data and associated engine data were used as inputs to EPA’s Advanced Light-duty Powertrain and Hybrid Analysis (ALPHA) vehicle simulation model. The ALPHA model simulated the GHG emissions from the 2018 Toyota Camry containing this engine and transmission, and the results were compared to vehicle chassis dynamometer test to validate the model. The torque loss map for the Toyota UB80E was then compared to other benchmarked transmission…
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Sensitivity Analysis of Aerodynamic Drag Coefficient to EPA Coastdown Ambient Condition Variation

FCA US LLC-Todd Lounsberry, John Tripp, Gregory Fadler
  • Technical Paper
  • 2020-01-0666
To be published on 2020-04-14 by SAE International in United States
The test cycle average drag coefficient is examined for the variation of allowable EPA coastdown ambient conditions. Coastdown tests are ideally performed with zero wind and at SAE standard conditions. However, often there is some variability in actual ambient weather conditions during testing, and the range of acceptable conditions is further examined in detail as it pertains to the effect on aerodynamic drag derived from the coastdown data. In order to “box” the conditions acceptable during a coastdown test, a sensitivity analysis was performed for wind averaged drag ((CDW ) ̅) as well as test cycle averaged drag coefficients (CDWC) for the fuel economy test cycles. Test cycle average drag for average wind speeds up to 16 km/h and temperatures ranging from 5C to 35C, along with variation of barometric pressure and relative humidity are calculated. The significant effect of ambient cross winds on coastdown determined drag coefficient is demonstrated.
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Impact of multi-mode range and location on fuel economy on a light-duty spark-ignition based powertrain using vehicle system simulations

Oak Ridge National Laboratory-Scott Curran, Robert Wagner
  • Technical Paper
  • 2020-01-1018
To be published on 2020-04-14 by SAE International in United States
Advanced compression ignition (ACI) modes have been shown to offer higher brake thermal efficiency than conventional spark ignition combustion with gasoline range fuels. The goal of a full-time ACI in which an ACI mode can be operated in over the entire speed and load map in a conventional passenger vehicle have been limited to date. The benefits of running ACI modes in a portion of the engine operating map have been shown in a number of studies to have potential benefits on improving fuel economy and reducing emissions. An engine that runs in two different combustion modes is known as a multi-mode strategy. Different multi-mode strategies have been proposed and demonstrated in laboratory and in demo vehicle settings. Multi-mode combustion strategies for vehicle applications offer the ability to maintain functionality expected for the real-world and certification driving cycles but offer part-time higher-efficiency/ lower emissions operation during a sufficient portion of the expected drive/duty cycle to offer significant fuel economy benefits as well as potential emissions controls benefits. There are challenges as well in both combustion…
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Single vs Double Stage Partial Flow Dilution System: Automobile PM Emission Measurement

Clemson University-Chirag Basrur
Cummins Technical Center-Yusuf Khan, Chet Mun Liew
  • Technical Paper
  • 2020-01-0366
To be published on 2020-04-14 by SAE International in United States
California Air Resource Board already introduced LEV III PM emission regulation (1mg/mi by 2028). It will be challenging to quantify such ultra-low PM by using conventional full flow Constant Volume Sampling (CVS) system. Sampling technique alternative to a CVS such as a Partial Flow Dilution System (PFDS) has already been introduced. Collecting PM on a single filter by using flow weighting is one options to load traceable amount of PM (Preferably more than 100 micrograms) on filter. Lower Dilution Ratios (DR) and higher Filter Face Velocity (FFV) are options to load traceable amount of PM on filter media in case of Light Duty Vehicle (LDV) testing. On the other hand Heavy Duty Engine (HDE) testing requires higher DR and lower FFV is to keep the amount of PM on filter less than 400 micrograms. PFDS with a single dilution tunnel cannot support both the LDV and HDE testing where a wide range of FFV and DR are required. A new PFDS with 2-stage dilution has been developed in the previous study. Two identical dilution tunnel…
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Motor Vehicle Emission Control Quality Monitoring for On-Road Driving -- Dynamic Signature Recognition of NOx & NH3 Emissions

US Environmental Protection Agency-Xiaoguo Tang, John Kargul, Dan McBryde
  • Technical Paper
  • 2020-01-0372
To be published on 2020-04-14 by SAE International in United States
Motor vehicles road drive emission test is important for exhaust emission regulation design/compliance and therefore the atmosphere air quality assessment. US EPA NVFEL has been developing a new approach of emission control dynamic signature to measure vehicle powertrain emission control behavior during both road and dyno driving. This so called signature device equipped with O2/NOx sensor, thermocouple and GPS to record exhaust NOx concentration, air fuel ratio controlled lambda, tailpipe temperature and vehicle speed (acceleration) dynamic signals. At the first stage, it was used to describe PCM control behaviors (cause/effect bijectivity) , then through a trained artificial neural-net (ANN) to distinguish normal control state-space and abnormal state-space (space distance). For the current stage, the emission control dynamic signature is used further to recognize NH3 releasing, and estimate NOx+NH3 during road and dyno driving, since the NH3 conversion can be observed by NOx sensor plus lambda rich biased reading after engine TWC warmed up. Stoich engine exhaust with TWC under certain conditions can have: CO+H2O→H2 & CO+NO+H2→NH3, it converts two regulated species into one unregulated compound,…
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Relevance of exhaust aftertreatment degradation for EU7 gasoline engine applications

FEV Europe GmbH-Michael Görgen, Jim Cox, Martin Nijs, Johannes Scharf
RWTH Aachen University-Stefan Sterlepper, Johannes Claßen, Stefan Pischinger
  • Technical Paper
  • 2020-01-0382
To be published on 2020-04-14 by SAE International in United States
Exhaust aftertreatment systems must function sufficiently over the full useful life of a vehicle. In Europe this is currently defined as 160.000 km, but it is expected that with introduction of EU7, the required mileage will be extended to 240.000 km. This will then be consistent with the US legislation. While emission limits are tightened, additional engine operation areas become relevant for certification. This results in new challenges in terms of limiting the deterioration of the conversion efficiencies of the exhaust aftertreatment system during the life of the vehicle. Before this backdrop, three-way catalyst aging and gasoline particulate filter ash accumulation are investigated in this paper. An advanced gasoline exhaust aftertreatment system with high platinum group metals loading, as expected necessary for the EU7, is evaluated. The system is aged using different cycles, such as the Standard Bench Cycle, the ZDAKW cycle for gasoline exhaust systems (a cycle developed by the German Exhaust Center for the Automotive Industry) and supplemented with borderline catalyst aging as well as a novel ash loading method. All aging operations…
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Statistical Model for the Prediction of Shift Points for Manual Motorcycles

U.S. Environmental Protection Agency-Peter James Caffrey
  • Technical Paper
  • 2020-01-1046
To be published on 2020-04-14 by SAE International in United States
Emissions from manual transmission motorcycles have been shown to be dependent upon transmission shift patterns. Presently, when undergoing an emission test for EPA certification a manufacturer can designate their own shift points during the cycle or utilize an Environmental Protection Agency (EPA) prescribed shift pattern which uses basic up or down shifts at specific speeds regardless of the type of motorcycle. In order to predict the real-life emissions from motorcycles, a comparative real-life shift pattern has been developed which can then be used to evaluate the suitability of the manufacturer’s shift schedule. To that end, a model that predicts shift points for motorcycles has been created. This model is based on the actual operation of different motorcycles by real life operators in a combined city and highway operational setting. Recognizing that no model is sufficient to adequately predict user operation in all situations, this model maintains a degree of flexibility in allowing the user to designate various limits to the shift probability, thus representing various rider scenarios. This would include a broad range of probability…