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Technical Paper

CVT Auto Cruise Ratio Control Using Adaptive Sliding Mode Control

Cruise control is one of the most critical issues that manufacturers concern about. But last many researches just focused on engine side control with general step transmission. Continuously Variable Transmissions (CVT) can cover a wide range of ratios continuously. This makes it possible to operate a combustion engine in more efficient working points than stepped transmission. With this merit, fuel optimal cruise control by CVT ratio control is possible with precise longitudinal dynamic model. Estimation of longitudinal load such as road slope and rolling resistance is essential for precise cruise control of automotive vehicle. In this paper, using model based road slope estimation method with gravity sensor, precise longitudinal dynamic model of automotive vehicle is presented. Real-time adaptive algorithm is also implemented for detecting external driving condition change and compensating bias of g-sensor.
Technical Paper

Efficacy of In-Cylinder Control of Particulate Emissions to Meet Current and Future Regulatory Standards

Diesel particulate filter (DPF) technology has proven performance and reliability. However, the addition of a DPF adds significant cost and packaging constraints leading some manufacturers to design engines that reduce particulate matter in-cylinder. Such engines utilize high fuel injection pressure, moderate exhaust gas recirculation and modified injection timing to mitigate soot formation. This study examines such an engine designed to meet US EPA Interim Tier 4 standards for off-highway applications without a DPF. The engine was operated at four steady state modes and aerosol measurements were made using a two-stage, ejector dilution system with a scanning mobility particle sizer (SMPS) equipped with a catalytic stripper (CS) to differentiate semi-volatile versus solid components in the exhaust. Gaseous emissions were measured using an FTIR analyzer and particulate matter mass emissions were estimated using SMPS data and an assumed particle density function.
Technical Paper

Significance of Fuel Sulfur Content and Dilution Conditions on Particle Emissions from a Heavily-Used Diesel Engine During Transient Operation

The effects of fuel sulfur content and dilution conditions on diesel engine PM number emissions have been researched extensively through steady state testing. Most results show that the concentration of nuclei-mode particles emitted increases with fuel sulfur content. A few studies further observed that fuel sulfur content has little effect on the emissions of heavily-used engines. It has also been found that primary dilution conditions can have a large impact on the size and number distribution of the nuclei-mode particles. These effects, however, have not yet been fully understood through transient testing, the method used by governments worldwide to certify engines and regulate emissions, and a means of experimentation which generates realistic conditions of on-road vehicles by varying the load and speed of the engine.
Technical Paper

Comparing Measurements of Carbon in Diesel Exhaust Aerosols Using the Aethalometer, NIOSH Method 5040, and SMPS

Combustion aerosols consist mainly of elemental and organic carbon (EC and OC). Since EC strongly absorbs light and thus affects atmospheric visibility and radiation balance, there is great interest in its measurement. To this end, the National Institute for Occupational Safety and Health (NIOSH) published a standard method to determine the mass of EC and OC on filter samples. Another common method of measuring carbon in aerosols is the aethalometer, which uses light extinction to measure “black carbon” or BC, which is considered to approximate EC. A third method sometimes used for estimating carbon in submicron combustion aerosols, is to measure particle size distributions using a scanning mobility particle sizer (SMPS) and calculate mass using the assumptions that the particles are spherical, carbonaceous and of known density.
Technical Paper

Improvement of Intake Restrictor Performance for a Formula SAE Race Car through 1D & Coupled 1D/3D Analysis Methods

A typical means of limiting the peak power output of race car engines is to restrict the maximum mass flow of air to the engine. The Formula SAE sanctioning body requires the use of an intake restrictor to limit performance, keep costs low, and maintain a safe racing experience. The intake restrictor poses a challenge to improving engine performance. Methods to better understand the ramifications of the restrictor on the engine lead to performance improvements that allow an edge over the competition. A one-dimensional gas exchange simulation code coupled with three-dimensional CFD is used to simulate various concepts in the improvement of restrictor performance. Ricardo's WAVE and VECTIS are the respective simulation codes. Along with this, the interaction of intake manifold and restrictor are considered. The effects of different diffuser geometries and plenum dimensions were first explored using WAVE, and then a series of different diffuser angles were simulated using WAVE-VECTIS.
Journal Article

Measuring Diesel Ash Emissions and Estimating Lube Oil Consumption Using a High Temperature Oxidation Method

Diesel engine ash emissions are composed of the non-combustible portions of diesel particulate matter derived mainly from lube oil, and over time can degrade diesel particulate filter performance. This paper presents results from a high temperature oxidation method (HTOM) used to estimate ash emissions, and engine oil consumption in real-time. Atomized lubrication oil and diesel engine exhaust were used to evaluate the HTOM performance. Atomized fresh and used lube oil experiments showed that the HTOM reached stable particle size distributions and concentrations at temperatures above 700°C. The HTOM produced very similar number and volume weighted particle size distributions for both types of lube oils. The particle number size distribution was unimodal, with a geometric mean diameter of about 23 nm. The volume size distribution had a geometric volume mean diameter of about 65 nm.
Technical Paper

Dynamic Modeling of Torque-Biasing Devices for Vehicle Yaw Control

This paper focuses on modeling of torque-biasing devices of a four-wheel-drive system used for improving vehicle stability and handling performance. The proposed driveline system is based on nominal front-wheel-drive operation with on-demand transfer of torque to the rear. The torque biasing components of the system are an electronically controlled center coupler and a rear electronically controlled limited slip differential. Kinematic modeling of the torque biasing devices is introduced including stage transitions during the locking stage and the unlocking/slipping stage. Analytical proofs of how torque biasing could be used to influence vehicle yaw dynamics are also included in the paper. A yaw control methodology utilizing the biasing devices is proposed. Finally, co-simulation results with Matlab®/Simulink® and CarSim® show the effectiveness of the torque biasing system in achieving yaw stability control.
Journal Article

Emissions Effects of Hydrogen as a Supplemental Fuel with Diesel and Biodiesel

A 1.9 liter Volkswagen TDI engine has been modified to accomodate the addition of hydrogen into the intake manifold via timed port fuel injection. Engine out particulate matter and the emissions of oxides of nitrogen were investigated. Two fuels,low sulfur diesel fuel (BP50) and soy methyl ester (SME) biodiesel (B99), were tested with supplemental hydrogen fueling. Three test conditions were selected to represent a range of engine operating modes. The tests were executed at 20, 40, and 60 % rated load with a constant engine speed o 1700 RPM. At each test condition the percentage of power from hydrogen energy was varied from 0 to 40 %. This corresponds to hydrogen flow rates ranging from 7 to 85 liters per minute. Particulate matter (PM) emissions were measured using a scaning mobility particle sizer (SMPS) and a two stage micro dilution system. Oxides of nitrogen were also monitored.
Journal Article

Late Intake Valve Closing as an Emissions Control Strategy at Tier 2 Bin 5 Engine-Out NOx Level

A fully flexible valve actuation (FFVA) system was developed for a single cylinder research engine to investigate high efficiency clean combustion (HECC) in a diesel engine. The main objectives of the study were to examine the emissions, performance, and combustion characteristics of the engine using late intake valve closing (LIVC) to determine the benefits and limitations of this strategy to meet Tier 2 Bin 5 NOx requirements without after-treatment. The most significant benefit of LIVC is a reduction in particulates due to the longer ignition delay time and a subsequent reduction in local fuel rich combustion zones. More than a 95% reduction in particulates was observed at some operating conditions. Combustion noise was also reduced at low and medium loads due to slower heat release. Although it is difficult to assess the fuel economy benefits of LIVC using a single cylinder engine, LIVC shows the potential to improve the fuel economy through several approaches.
Technical Paper

Particle and Gaseous Emission Characteristics of a Formula SAE Race Car Engine

The focus of this work was the physical characterization of exhaust aerosol from the University of Minnesota Formula SAE team's engine. This was done using two competition fuels, 100 octane race fuel and E85. Three engine conditions were evaluated: 6000 RPM 75% throttle, 8000 RPM 50% throttle, and 8000 RPM 100% throttle. Dilute emissions were characterized using a Scanning Mobility Particle Sizer (SMPS) and a Condensation Particle Counter (CPC). E85 fuel produced more power and had lower particulate matter emissions at all test conditions, but more fuel was consumed.
Technical Paper

Diesel Trap Performance: Particle Size Measurements and Trends

Particle concentrations and size distributions were measured in the exhaust of a turbocharged, aftercooled, direct-injection, Diesel engine equipped with a ceramic filter (trap). Measurements were performed both upstream and downstream of the filter using a two-stage, variable residence time, micro-dilution system, a condensation particle counter and a scanning mobility particle sizer set up to count and size particles in the 7-320 nm diameter range. Engine operating conditions of the ISO 11 Mode test were used. The engine out (upstream of filter) size distribution has a bimodal, log normal structure, consisting of a nuclei mode with a geometric number mean diameter, DGN, in the 10-30 nm range and an accumulation mode with DGN in the 50-80 nm range. The modal structure of the size distribution is less distinct downstream of the filter. Nearly all the particle number emissions come from the nuclei mode, are nanoparticles (Dp < 50nm), and are volatile.
Technical Paper

Towards Human Friendly Hydraulics - Passive Teleoperation of Hydraulic Equipment Using a Force Feedback Joystick

Hydraulic systems, as power source and transmission, offer many advantages over electromechanical or purely mechanical counterparts in terms of power density, flexibility and portability. Many hydraulic systems require touching and contacting the physical environments; and many of these systems are directly controlled by human. If hydraulic systems are passive, they would be safer to interact with, and easier for human to control. In this paper, we describe our current research in developing bilateral passive teleoperated hydraulic machines which a human operator controls via a force feedback joystick. Two key developments are 1) methodologies to passify the electrohydraulic valves as a two-port device, and 2) the passive teleoperation controllers.
Technical Paper

Dust Loading Behavior of Engine and General Purpose Air Cleaning Filters

The purpose of this study is to compare the dust loading behavior of ten filter media. The filters are used in engine air filtration, self-cleaning industrial air cleaners, building heating ventilation and cooling (HVAC), automotive cabin air filtration, air respirators, and general purpose air cleaning. Several types of filter media are tested. The filters include cellulose, synthetic (felt), glass, dual-layered glass/cellulose, mixed synthetic/glass, gradient packing glass, and electrically charged fibers. The initial pressure drops and fractional collection efficiencies as a function of particle size are reported. The filters were evaluated with two test dusts to investigate the size-dependent dust loading behavior. The two test dusts are SAE fine and submicron alumina powder (median diameter 0.25 μm). The results are analyzed and compared. It was found that the cellulose filters exhibited surface loading behavior and have the fastest growth of pressure drops.
Technical Paper

A Bimodal Loading Test for Engine and General Purpose Air Cleaning Filters

The dust holding capacity of air cleaning filter depends on the size distribution of the particles. Traditional test dusts like Arizona road dust consist of a single mode of coarse particles. The purpose of this study is to evaluate the dust holding capacities of air filters with a bi-modal test dust that simulates the dust in atmospheric environments. The fine mode of the test dust consists of submicron Alumina particles that represent the fine particles in atmosphere. The coarse mode consists of traditional AC fine dust. The fine and coarse dusts are mixed in different mass ratios to simulate different atmospheric conditions. The ratios are 100% fine, 50%/50%, 25%/75%, 10%/90%, and 100% coarse. An engine air filter and a HVAC filter were studied with the bi-modal test dusts. The filter pressure drops were measured as a function of the dust loading. The results show that the flow resistance rises significantly faster as the ratio of fine to coarse fraction increases.
Technical Paper

Experimental Measurement of Clean Fractional Efficiency of Engine Air Cleaning Filters

The function of the engine air cleaning filter is to remove the particulate matter in the intake air to protect the engine and its components from wear and contamination. For a specific filter, the efficiency is a function of the size of the particles being collected and the air flow velocity through the filter. Traditional tests of engine air cleaners are based on the use of specific test dusts, such as the AC Coarse and AC Fine, to determine the mass collection efficiency. However, they do not provide information on the size dependent performance of the filters, and the variation in filter performance under different particle challenge conditions. The use of a fractional efficiency test method will help to provide this missing information. The purpose of this paper is to describe a fractional efficiency test system that has been designed to evaluate the fractional cleaning efficiency of engine air cleaning filters in the size range between 0.3 and 10 mm particle diameter.
Technical Paper

Effects of Variable Piston Trajectory on Indicated Efficiency Using a Quasi-Dimensional Spark-Ignition Model and Genetic Algorithm Optimization

The impact of compression ratio on engine efficiency is well known. A plethora of mechanical concepts have been proposed for altering engine compression ratio in real time. Some of these, like free-piston configurations or complex crank-slider mechanisms have the added ability to alter piston trajectory along with compression ratio. This secondary modality raises the question: Is there a more optimal piston position versus crank-angle profile for spark-ignition (SI) engines than the near-sinusoidal motion produced by a traditional four-bar crank-slider mechanism? Very little published literature directly addresses this question. This work presents the results of a quasi-dimensional SI engine model using piston trajectory as an input. Specific trajectory traits including increased dwell at top dead center and asymmetric compression and expansion strokes were swept. The trajectory also was optimized using a single objective genetic algorithm with 60 individuals and 40 generations.
Journal Article

Investigation of Fuel Effects on In-Cylinder Reforming Chemistry Using Gas Chromatography

Negative Valve Overlap (NVO) is a potential control strategy for enabling Low-Temperature Gasoline Combustion (LTGC) at low loads. While the thermal effects of NVO fueling on main combustion are well-understood, the chemical effects of NVO in-cylinder fuel reforming have not been extensively studied. The objective of this work is to examine the effects of fuel molecular structure on NVO fuel reforming using gas sampling and detailed speciation by gas chromatography. Engine gas samples were collected from a single-cylinder research engine at the end of the NVO period using a custom dump-valve apparatus. Six fuel components were studied at two injection timings: (1) iso-octane, (2) n-heptane, (3) ethanol, (4) 1-hexene, (5) cyclohexane, and (6) toluene. All fuel components were studied neat except for toluene - toluene was blended with 18.9% nheptane by liquid volume to increase the fuel reactivity.
Technical Paper

Investigation of Species from Negative Valve Overlap Reforming Using a Stochastic Reactor Model

Fuel reforming during a Negative Valve Overlap (NVO) period is an effective approach to control Low Temperature Gasoline Combustion (LTGC) ignition. Previous work has shown through experiments that primary reference fuels reform easily and produce several species that drastically affect ignition characteristics. However, our previous research has been unable to accurately predict measured reformate composition at the end of the NVO period using simple single-zone models. In this work, we use a stochastic reactor model (SRM) closed cycle engine simulation to predict reformate composition accounting for in-cylinder temperature and mixture stratification. The SRM model is less computationally intensive than CFD simulations while still allowing the use of large chemical mechanisms to predict intermediate species formation rates.
Technical Paper

Influence of Fuel Additives and Dilution Conditions on the Formation and Emission of Exhaust Particulate Matter from a Direct Injection Spark Ignition Engine

Experiments were performed to measure the number-weighted particle size distributions emitted from a gasoline direct injection (GDI) engine. Measurements were made on a late model vehicle equipped with a direct injection spark ignition engine. The vehicle was placed on a chassis dynamometer, which was used to load the engine to road load at five different vehicle speeds ranging from 15 - 100 km/hr. Dilution of the exhaust aerosol was carried out using a two-stage dilution system in which the first stage dilution occurs as a free jet. Particle size distributions were measured using a TSI 3934 scanning mobility particle sizer. Generally speaking, the presence of the additives did not have a strong, consistent influence on the particle emissions from this engine. The polyether amine demonstrated a reduction in particle number concentration as compared to unadditized base fuel.
Technical Paper

The Influence of Dilution Conditions on Diesel Exhaust Particle Size Distribution Measurements

Particle size distribution and number concentration measurements have been made in the diluted exhaust of a medium-duty, turbocharged, aftercooled, direct-injection Diesel engine using a unique variable residence time micro-dilution system that allows systematic variation of dilution and sampling conditions, and a scanning mobility particle sizer (SMPS). The measurements show that the number concentrations in the nanoparticle (Dp < 50 nm) and the ultrafine (Dp < 100 nm) ranges are very sensitive to dilution conditions and fuel sulfur content. Changes in concentration of up to two orders of magnitude have been observed when conditions are varied over the range that might be encountered in typical laboratory dilution systems. For example, at a dilution ratio of 12, dilution temperature of 32 °C, and a residence time of 1000 ms, the number concentrations reach 6 × 108 part.