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This investigation was aimed at measuring the relative performance of two spray-guided, single-cylinder, spark-ignited direct-injected (SIDI) engine combustion system designs. The first utilizes an outwardly-opening poppet, piezo-actuated injector, and the second a conventional, solenoid operated, inwardly-opening multi-hole injector. The single-cylinder engine tests were limited to steady state, warmed-up conditions. The comparison showed that these two spray-guided combustion systems with two very different sprays had surprisingly close results and only differed in some details. Combustion stability and smoke emissions of the systems are comparable to each other over most of the load range. Over a simulated Federal Test Procedure (FTP) cycle, the multi-hole system had 15% lower hydrocarbon and 18% lower carbon monoxide emissions.

In a gasoline engine, the unswept in-cylinder residual gas and introduction of external EGR is one of the important means of controlling engine raw NOx emissions and improving part load fuel economy via reduction of pumping losses. Since the trapped in-cylinder Residual Gas Fraction (RGF, comprised of both internal, and external) significantly affects the combustion process, on-line diagnosis and monitoring of in-cylinder RGF is very important to the understanding of the in-cylinder dilution condition. This is critical during the combustion system development testing and calibration processes. However, on-line measurement of in-cylinder RGF is difficult and requires an expensive exhaust gas analyzer, making it impractical for every application. Other existing methods, based on measured intake and exhaust pressures (steady state or dynamic traces) to calculate gas mass flowrate across the cylinder ports, provide a fast and economical solution to this problem.

A pilot study was performed to explore the effects of PM Index, low and high molecular weight aromatics, and ethanol content on particulate matter (PM) emissions from light-duty Tier 2 gasoline vehicles. Four test vehicles from model years 2007-2009 were tested on seven fuels spanning PM Index values from 0.9 to 2.7, aromatic content from 14 to 38%, and ethanol content from 0 to 15%. Three of the test vehicles were port fuel injected (PFI) while the fourth featured gasoline direct injection (GDI). In an earlier program, two of the PFI vehicles demonstrated high sensitivity of PM emissions to fuel property changes while the third showed low sensitivity. The sensitivity of the GDI vehicle to fuel property changes was not known prior to this study. The vehicles were tested over the LA92 and US06 test cycles at 24°C (75°F). PM and regulated gaseous emissions were measured by test phase. Second-by-second tailpipe soot emissions were measured using the AVL Micro Soot Sensor.

Accurate accounting for fresh charge (fuel and air) along with trapped RGF is essential for the subsequent thermodynamic analysis of combustion in gasoline engines as well as for on-line and real-time quantification as relevant to engine calibration and control. Cost and complexity of such techniques renders direct measurement of RGF impractical for running engines. In this paper, an empirically-based approach is proposed for on-line RGF, based on an existing semi-empirical model [1]. The model developed expands the range over which the semi-empirical model is valid and further improves its accuracy. The model was rigorously validated against a well correlated GT-POWER model as well as results from 1D gas exchange model [2]. Overall, using this model, RGF estimation error was within ∼1.5% for a wide range of engine operating conditions. The model will be implemented in Dyno development and calibration at Chrysler Group.

As part of the U.S. Environmental Protection Agency (U.S. EPA) “Midterm Evaluation of Light-duty Vehicle Standards for Model Years 2022-2025 [1]”, the U.S. EPA is evaluating engines and assessing the effectiveness of future engine technologies for reducing CO2 emissions. Such assessments often require significant development time and resources in order to optimize intake and exhaust cam variable valve timing (VVT), exhaust gas recirculation (EGR) flow rates, and compression ratio (CR) changes. Mazda SkyActiv-G spark-ignition (SI) engines were selected by EPA for an internal engine development program based upon their high geometric compression ratio (14:1 in Europe and Japan, 13:1 in North America) and their use of a flexible valve train configuration with electro-mechanical phasing control on the intake camshaft. A one-dimensional GT-Power engine model was calibrated and validated using detailed engine dynamometer test data [2] from 2.0L and 2.5L versions of the SkyActiv-G engine.

This paper reports on DaimlerChrysler's participation in the Ad Hoc Diesel Fuels Test Program. This program was initiated by the U.S. Department of Energy and included major U.S. auto makers, major U.S. oil companies, and the Department of Energy. The purpose of this program was to identify diesel fuels and fuel properties that could facilitate the successful use of compression ignition engines in passenger cars and light-duty trucks in the United States at Tier 2 and LEV II tailpipe emissions standards. This portion of the program focused on minimizing engine-out particulates and NOx by using selected fuels, (not a matrix of fuel properties,) in steady state dynamometer tests on a modern, direct injection, common rail diesel engine.

Homogenous charge compression ignition (HCCI) engines offer a great potential in achieving high thermal efficiency and extremely low NOx at the same time. However, control of combustion phasing over a wide speed and load range has been a challenge, especially during transient operations. This paper describes work conducted at the National Vehicle and Fuel Emissions Laboratory, which explores the potential use of an HCCI engine as a power plant for a hybrid vehicle. A four-cylinder, 1.9 L commercial diesel engine was modified to operate with port-injected regular grade gasoline in HCCI mode. The combustion phasing is controlled by a combination of boost, EGR and thermal management as a function of engine speed and load. As a stand-alone unit, the engine has demonstrated a wide operation range with efficiency like that of a diesel engine and NOx below 0.2 g/kWh. At room temperature, the engine starts in SI mode and then transitions to HCCI in about 25 seconds.

This paper examines the pace at which manufacturers have added certain powertrain technology into new vehicles from model year 1975 to the present. Based on data from the EPA's Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends database [1], the analysis will focus on several key technologies that have either reached a high level of penetration in light duty vehicles, or whose use in the new vehicle fleet has been growing in recent years. The findings indicate that individual manufacturers have, at times, implemented new technology across major portions of their new vehicle offerings in only a few model years. This is an important clarification to prior EPA analysis that indicated much longer adoption times for the industry as a whole. This new analysis suggests a technology penetration paradigm where individual manufacturers have a much shorter technology penetration cycle than the overall industry, due to “sequencing” by individual manufacturers.

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 A25A-FKS 4-cylinder, 2.5-liter, naturally aspirated, Atkinson Cycle engine with cooled exhaust gas recirculation (cEGR) was benchmarked. The engine was tested on an engine dynamometer with and without its 8-speed automatic transmission, and with the engine wiring harness tethered to a complete vehicle parked outside of the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, onboard diagnostics (OBD) data, and Controller Area Network (CAN) bus data were recorded. This paper documents the test results under idle, low, medium, and high load engine operation. Motoring torque, wide open throttle (WOT) torque and fuel consumption are measured during transient operation using both EPA Tier 2 and Tier 3 test fuels.

Cam-phasing is increasingly considered as a feasible Variable Valve Timing (VVT) technology for production engines. Additional independent control variables in a dual-independent VVT engine increase the complexity of the system, and achieving its full benefit depends critically on devising an optimum control strategy. A traditional approach relying on hardware experiments to generate set-point maps for all independent control variables leads to an exponential increase in the number of required tests and prohibitive cost. Instead, this work formulates the task of defining actuator set-points as an optimization problem. In our previous study, an optimization framework was developed and demonstrated with the objective of maximizing torque at full load. This study extends the technique and uses the optimization framework to minimize fuel consumption of a VVT engine at part load.

In-use, light-duty vehicles were recruited in Cary, North Carolina for emissions testing on a transportable dynamometer in 1999. Two hundred forty-eight vehicles were tested in as received condition using the IM240 driving cycle. The study was conducted in two phases, a summer and winter phase, with half of the vehicles recruited during each phase. Regulated emissions, PM10, carbonaceous PM, aldehydes and ketones were measured for every test. PM2.5, individual volatile hydrocarbons, polycyclic aromatic hydrocarbons, sterane and hopane emissions were measured from a subset of the vehicles. Average light-duty gasoline PM10 emission rates increased from 6.5 mg/mi for 1993-97 vehicles to 53.8 mg/mi for the pre-1985 vehicles. The recruited fleet average, hot-stabilized IM240 PM10 emission rate for gasoline vehicles was 19.0 mg/mi.

The U.S. Environmental Protection Agency, U.S. Department of Transportation's National Highway and Traffic Safety Administration, and the California Air Resources Board have recently released proposed new regulations for greenhouse gas emissions and fuel economy for light-duty vehicles and trucks in model years 2017-2025. These proposed regulations intend to significantly reduce greenhouse gas emissions and increase fleet fuel economy from current levels. At the fleet level, these rules the proposed regulations represent a 50% reduction in greenhouse gas emissions by new vehicles in 2025 compared to current fleet levels. At the same time, global growth, especially in developing economies, should continue to drive demand for crude oil and may lead to further fuel price increases. Both of these trends will therefore require light duty vehicles (LDV) to significantly improve their greenhouse gas emissions over the next 5-15 years to meet regulatory requirements and customer demand.

This paper summarizes the Heavy-Duty In-Use Testing (HDUIT) measurement allowance program for Particulate Matter Portable Emissions Measurement Systems (PM-PEMS). The measurement allowance program was designed to determine the incremental error between PM measurements using the laboratory constant volume sampler (CVS) filter method and in-use testing with a PEMS. Two independent PM-PEMS that included the Sensors Portable Particulate Measuring Device (PPMD) and the Horiba Transient Particulate Matter (TRPM) were used in this program. An additional instrument that included the AVL Micro Soot Sensor (MSS) was used in conjunction with the Sensors PPMD to be considered a PM-PEMS. A series of steady state and transient tests were performed in a 40 CFR Part 1065 compliant engine dynamometer test cell using a 2007 on-highway heavy-duty diesel engine to quantify the accuracy and precision of the PEMS in comparison with the CVS filter-based method.

The Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created by EPA to estimate greenhouse gas (GHG) emissions from light-duty (LD) vehicles [1]. ALPHA is a physics-based, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types combined with different powertrain technologies. The software tool is a MATLAB/Simulink based desktop application. In order to model the behavior of current and future vehicles, an algorithm was developed to dynamically generate transmission shift logic from a set of user-defined parameters, a cost function (e.g., engine fuel consumption) and vehicle performance during simulation. This paper presents ALPHA's shift logic algorithm and compares its predicted shift points to actual shift points from a mid-size light-duty vehicle and to the shift points predicted using a static table-based shift logic as calibrated to the same vehicle during benchmark testing.

The Fischer-Tropsch (FT) process can be used to synthesize diesel fuels from a variety of energy sources, including coal, natural gas and biomass. Diesel fuels produced from the FT process are essentially sulfur-free, have very low aromatic content, and have excellent ignition characteristics. Because of these favorable attributes, FT diesel fuels may offer environmental benefits over transportation fuels derived from crude oil. Previous tests have shown that FT diesel fuel can be used in unmodified engines and have been shown to lower regulated emissions. Whereas exhaust emissions reductions from these previous studies have been impressive, this paper demonstrates that far greater exhaust emissions reductions are possible if the diesel engine is optimized to exploit the properties of the FT fuels. A Power Stroke 7.3 liter turbocharged diesel engine has been modified for use with FT diesel.

Current engine development processes typically involve extensive steady-state and simple transient testing in order to characterize the engine's fuel consumption, emissions, and performance based on several controllable inputs such as throttle, spark advance, and EGR. Steady-state and simple transient testing using idealistic load conditions alone, however, is no longer sufficient to meet powertrain development schedule requirements. Mapping and calibration of an engine under transient operation has become critically important. And, independent engine development utilizing accelerated techniques is becoming more attractive. In order to thoroughly calibrate new engines in accelerated fashion and under realistic transient conditions, more advanced testing is necessary.

The Automotive Industry/Government Emissions Research CRADA (AIGER) has been working to develop a new methodology for the direct determination of nonmethane hydrocarbons (DNMHC) in vehicle testing. This new measurement technique avoids the need for subtraction of a separately determined methane value from the total hydrocarbon measurement as is presently required by the Code of Federal Regulations. This paper will cover the historical aspects of the development program, which was initiated in 1993 and concluded in 2002. A fast, gas chromatographic (GC) column technology was selected and developed for the measurement of the nonmethane hydrocarbons directly, without any interference or correction being caused by the co-presence of sample methane. This new methodology chromatographically separates the methane from the nonmethane hydrocarbons, and then measures both the methane and the backflushed, total nonmethane hydrocarbons using standard flame ionization detection (FID).

The Ethanol-Boosted Direct Injection (EBDI) demonstrator engine is a collaborative project led by Ricardo targeted at reducing the fuel consumption of a spark-ignited engine. This paper describes the design challenges to upgrade an existing engine architecture and the synergistic use of a combination of technologies that allows a significant reduction in fuel consumption and CO₂ emissions. Features include an extremely reduced displacement for the target vehicle, 180 bar cylinder pressure capability, cooled exhaust gas recirculation, advanced boosting concepts and direct injection. Precise harmonization of these individual technologies and control algorithms provide optimized operation on gasoline of varying octane and ethanol content.

Chassis dynamometer testing was conducted with three on-highway motorcycles produced for the North American market with engine displacements of 296 cc, 749 cc and 1198 cc to better inform criteria pollutant emissions inventories. The motorcycles were tested using US Tier 2 certification fuel over the Federal Test Procedure (FTP), World Motorcycle Test Cycle (WMTC) and a cycle based on a sample of real-world motorcycle driving, informally referred to as the ‘Real World Driving Cycle’ (RWDC). Emissions characterization includes composite, individual test phase and 1Hz cumulative results for various criteria pollutants for each test cycle. Overall, it was found that the higher peak speed rates and peak torque levels observed during the RWDC are more fully represented in the WMTC than the FTP. The use of the WMTC and RWDC cycles generally translated into higher emissions rates compared to the FTP and in particular for nitrogen oxides and carbon monoxide.

Chassis dynamometer tests were conducted on three Class III on-highway motorcycles produced for the North American market and equipped with advanced emission control technologies in order to inform emissions inventories and compare the impacts of existing Tier 2 (E0) fuel with more market representative Tier 3 and LEV III certification fuels with 10% ethanol. For this study, the motorcycles were tested over the US Federal Test Procedure (FTP) and the World Motorcycle Test Cycle (WMTC) certification test cycles as well as a sample of real-world motorcycle driving informally referred to as the Real World Driving Cycle (RWDC). The primary interest was to understand the emissions changes of the selected motorcycles with the use of certification fuels containing 10% ethanol compared to 0% ethanol over the three test cycles.