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Viewing 241 to 270 of 16480
2017-03-28
Journal Article
2017-01-1182
Xin Guo, Xu Peng, Sichuan Xu
Abstract Startup from subzero temperature is one of the major challenges for polymer electrolyte membrane fuel cell (PEMFC) to realize commercialization. Below the freezing point (0°C), water will freeze easily, which blocks the reactant gases into the reaction sites, thus leading to the start failure and material degradation. Therefore, for PEMFC in vehicle application, finding suitable ways to reach successful startup from subfreezing environment is a prerequisite. As it’s difficult and complex for experimental studies to measure the internal quantities, mathematical models are the effective ways to study the detailed transport process and physical phenomenon, which make it possible to achieve detailed prediction of the inner life of the cell. However, review papers only on cold start numerical models are not available. In this study, an extensive review on cold start models is summarized featuring the states and phase changes of water, heat and mass transfer.
2017-03-28
Journal Article
2017-01-1179
Tatsuya Arai, Ozaki Takashi, Kazuki Amemiya, Tsuyoshi Takahashi
Abstract Polymer electrolyte membrane fuel cell (PEFC) systems for fuel cell vehicles (FCVs) require both performance and durability. Carbon is the typical support material used for PEFC catalysts. However, hydrogen starvation at the anode causes high electrode potential states (e.g., 1.3 V with respect to the reversible hydrogen electrode) that result in severe carbon support corrosion. Serious damage to the carbon support due to hydrogen starvation can lead to irreversible performance loss in PEFC systems. To avoid such high electrode potentials, FCV PEFC systems often utilize cell voltage monitor systems (CVMs) that are expensive to use and install. Simplifying PEFC systems by removing these CVMs would help reduce costs, which is a vital part of popularizing FCVs. However, one precondition for removing CVMs is the adoption of a durable support material to replace carbon.
2017-03-28
Journal Article
2017-01-1535
Luca Dalessio, Bradley Duncan, Chinwei Chang, Joaquin Ivan Gargoloff, Ed Tate
Abstract The ultimate goal for vehicle aerodynamicists is to develop vehicles that perform well on the road under real-world conditions. One of the most important metrics to evaluate vehicle performance is the drag coefficient. However, vehicle development today is performed mostly under controlled settings using wind tunnels and computational fluid dynamics (CFD) with artificially uniform upstream conditions, neglecting real-world effects due to road turbulence from wind and other vehicles. Thus, the drag coefficients computed with these methods might not be representative of the real performance of the car on the road. This might ultimately lead engineers to develop design solutions and aerodynamic devices which, while performing well in idealized conditions, do not perform well on the road. For this reason, it is important to assess the vehicle’s drag as seen in real-world environments. An effort in this direction is represented by using the wind-averaged drag.
2017-03-28
Journal Article
2017-01-0599
Yichao Guo
Abstract Misfire is generally defined as be no or partial combustion during the power stroke of internal combustion engine. Because a misfired engine will dramatically increase the exhaust emission and potentially cause permanent damage to the catalytic converters, California Air Resources Board (CARB), as well as most of other countries’ on-board diagnostic regulations mandates the detection of misfire. Currently almost all the OEMs utilize crankshaft position sensors as the main input to their misfire detection algorithm. The detailed detection approaches vary among different manufacturers. For example, some chooses the crankshaft angular velocity calculated from the raw output of the crankshaft positon sensor as the measurement to distinguish misfires from normal firing events, while others use crankshaft angular acceleration or the associated torque index derived from the crankshaft position sensor readings as the measurement of misfire detection.
2017-03-28
Journal Article
2017-01-1297
Robert Peckham, Sumit Basu, Marcelo Ribeiro, Sandra Walker
Abstract This study emphasizes the fact that there lies value and potential savings in harmonizing some of the inherent differences between the USA, EU, and China regulations with respect to the role of vehicle mass and lightweighting within Fuel Economy (FE) and Green House Gas (GHG) regulations. The definition and intricacies of FE and mass regulations for the three regions (USA, EU, and China) have been discussed and compared. In particular, the nuances of footprint-based, curb-mass-based, and stepped-mass-based regulations that lead to the differences have been discussed. Lightweighting is a customer benefit for fuel consumption, but in this work, we highlight cases where lightweighting, as a CO2 enabler, has incentives that do not align with rational customer values. A typical vehicle’s FE performance sensitivity to a change in mass on the standard regional certification drive cycles is simulated and compared across the three regions.
2017-03-28
Journal Article
2017-01-1313
Bao Wang, Jianhua Zhou, Min Xu
Abstract Manufacturing tolerances are inevitable in nature. For the bearings used in internal combustion engines, the manufacturing tolerances of roundness, which is of the micron scale, can be very close to the bearing radial clearance, and as a result the roundness could affect the lubrication of the bearings and thus affecting the friction loss of the engine. However, there is insufficient understanding of this mechanism. This study aims to find out the effects of the amplitude and the phase of journal roundness in the shape of ellipse on the lubrication of engine bearings. The elastohydrodynamic (EHD) theory is applied to model the bearing since the EHD model takes account of the elastic deformation of the journal and the bearing shell. The analysis of the DOE results shows the existence of roundness can be beneficial to the lubrication in some cases.
2017-03-28
Journal Article
2017-01-1513
Young-Chang Cho, Chin-Wei Chang, Andrea Shestopalov, Edward Tate
Abstract The airflow into the engine bay of a passenger car is used for cooling down essential components of the vehicle, such as powertrain, air-conditioning compressor, intake charge air, batteries, and brake systems, before it returns back to the external flow. When the intake ram pressure becomes high enough to supply surplus cooling air flow, this flow can be actively regulated by using arrays of grille shutters, namely active grille shutters (AGS), in order to reduce the drag penalty due to excessive cooling. In this study, the operation of AGS for a generic SUV-type model vehicle is optimized for improved fuel economy on a highway drive cycle (part of SFTP-US06) by using surrogate models. Both vehicle aerodynamic power consumption and under-hood cooling performance are assessed by using PowerFLOW, a high-fidelity flow solver that is fully coupled with powertrain heat exchanger models.
2017-03-28
Journal Article
2017-01-0930
Christine K. Lambert, Timothy Chanko, Mark Jagner, Jon Hangas, Xin Liu, James Pakko, Carl Justin Kamp
Abstract To meet future particle mass and particle number standards, gasoline vehicles may require particle control, either by way of an exhaust gas filter and/or engine modifications. Soot levels for gasoline engines are much lower than diesel engines; however, non-combustible material (ash) will be collected that can potentially cause increased backpressure, reduced power, and lower fuel economy. The purpose of this work was to examine the ash loading of gasoline particle filters (GPFs) during rapid aging cycles and at real time low mileages, and compare the filter performances to both fresh and very high mileage filters. Current rapid aging cycles for gasoline exhaust systems are designed to degrade the three-way catalyst washcoat both hydrothermally and chemically to represent full useful life catalysts. The ash generated during rapid aging was low in quantity although similar in quality to real time ash.
2017-03-28
Technical Paper
2017-01-0931
Michiel Van Nieuwstadt, Joseph Ulrey
Abstract While not commonly in production today, Gasoline Particulate Filters (GPFs) are likely to see widespread deployment to meet stringent EU6.2 and China particulate number (PN) standards. In many ways the operating conditions for GPFs are orthogonal to those of their diesel counterparts, and this leads to different and interesting requirements for the control strategy. We will present some generic system architectures for exhaust systems containing a GPF and will lay out an architecture for the GPF control strategy components which include: regeneration assist feature, soot estimation algorithm, GPF protection. The regeneration assist feature uses spark retard to increase exhaust temperature. The soot estimation algorithm describes how we can estimate soot from an open loop model or from a normalized pressure metric. The GPF protection feature controls oxygen flow to limit the soot burn rate.
2017-03-28
Technical Paper
2017-01-0683
Michael Fischer, Philipp Kreutziger, Yong Sun, Adam Kotrba
Abstract External Exhaust Gas Recirculation (EGR) has been used on diesel engines for decades and has also been used on gasoline engines in the past. It is recently reintroduced on gasoline engines to improve fuel economy at mid and high engine load conditions, where EGR can reduce throttling losses and fuel enrichment. Fuel enrichment causes fuel penalty and high soot particulates, as well as hydrocarbon (HC) emissions, all of which are limited by emissions regulations. Under stoichiometric conditions, gasoline engines can be operated at high EGR rates (> 20%), but more than diesel engines, its intake gas including external EGR needs extreme cooling (down to ~50°C) to gain the maximum fuel economy improvement. However, external EGR and its problems at low temperatures (fouling, corrosion & condensation) are well known.
2017-03-28
Technical Paper
2017-01-0932
Nehemiah S I Alozie, George Fern, David Peirce, Lionel Ganippa
Abstract The use of diesel particulate filter [DPF] has become a standard in modern diesel engine after treatment technology. However pressure drop develops across the filter as PM accumulates and this requires quick periodic burn-out without incurring thermal runaway temperatures that could compromise DPF integrity during operation. Adequate understanding of soot oxidation is needed for design and manufacture of efficient filter traps for the engine system. In this study, we have examined the impact of blending biodiesel on oxidation of PM generated from a high speed direct injection [HSDI] diesel engine, which was operated with 20% [B20] and 40% [B40] blends of two biodiesel fuels. The PM samples were collected from the engine exhaust using a Pall Tissuquartz filter, the oxidation characteristics of the samples were carried out using thermogravimetric analyzer [TGA]. The biodiesel oxidation data obtained from pure petrodiesel was compared against the fuel blends.
2017-03-28
Journal Article
2017-01-0271
Robert Jane, Gordon G. Parker, Wayne Weaver, Ronald Matthews, Denise Rizzo, Michael Cook
Abstract This paper considers optimal power management during the establishment of an expeditionary outpost using battery and vehicle assets for electrical generation. The first step in creating a new outpost is implementing the physical protection and barrier system. Afterwards, facilities that provide communications, fires, meals, and moral boosts are implemented that steadily increase the electrical load while dynamic events, such as patrols, can cause abrupt changes in the electrical load profile. Being able to create a fully functioning outpost within 72 hours is a typical objective where the electrical power generation starts with batteries, transitions to gasoline generators and is eventually replaced by diesel generators as the outpost matures.
2017-03-28
Journal Article
2017-01-0388
Haeyoon Jung, MiYeon Song, Sanghak Kim
Abstract CO2 emission is more serious in recent years and automobile manufacturers are interested in developing technologies to reduce CO2 emissions. Among various environmental-technologies, the use of solar roof as an electric energy source has been studied extensively. For example, in order to reduce the cabin ambient temperature, automotive manufacturers offer the option of mounting a solar cell on the roof of the vehicle [1]. In this paper, we introduce the semi-transparent solar cell mounted on a curved roof glass and we propose a solar energy management system to efficiently integrate the electricity generated from the solar roof into internal combustion engine (ICE) vehicles. In order to achieve a high efficiency solar system in different driving, we improve the usable power other than peak power of solar roof. Peak power or rated power is measured power (W) in standard test condition (@ 25°C, light intensity of 1000W/m2(=1Sun)).
2017-03-28
Journal Article
2017-01-0425
Hong Wang, Yanjun Huang, Chen Lv, Amir Khajepour
Abstract Energy management strategies greatly influence the power performance and fuel economy of series hybrid electric tracked bulldozers. In this paper, we present a procedure for the design of a power management strategy by defining a cost function, in this case, the minimization of the vehicle’s fuel consumption over a driving cycle. To explore the fuel-saving potential of a series hybrid electric tracked bulldozer, a dynamic programming (DP) algorithm is utilized to determine the optimal control actions for a series hybrid powertrain, and this can be the benchmark for the assessment of other control strategies. The results from comparing the DP strategy and the rule-based control strategy indicate that this procedure results in approximately a 7% improvement in fuel economy.
2017-03-28
Journal Article
2017-01-0587
Cetin Gurel, Elif Ozmen, Metin Yilmaz, Didem Aydin, Kerem Koprubasi
Abstract Emissions and fuel economy optimization of internal combustion engines is becoming more challenging as the stringency of worldwide emission regulations are constantly increasing. Aggressive transient characteristics of new emission test cycles result in transient operation where the majority of soot is produced for turbocharged diesel engines. Therefore soot optimization has become a central component of the engine calibration development process. Steady state approach for air-fuel ratio limitation calibration development is insufficient to capture the dynamic behavior of soot formation and torque build-up during transient engine operation. This paper presents a novel methodology which uses transient maneuvers to optimize the air-fuel ratio limitation calibration, focusing on the trade-off between vehicle performance and engine-out soot emissions. The proposed methodology features a procedure for determining candidate limitation curves with smoothness criteria considerations.
2017-03-28
Journal Article
2017-01-0586
Hayato Shirai, Hayato Nakada, Akio Matsunaga, Hiroyuki Tominaga
Abstract In real-world automotive control, there are many constraints to be considered. In order to explicitly treat the constraints, we introduce a model-prediction-based algorithm called a reference governor (RG). The RG generates modified references so that predicted future variables in a closed-loop system satisfy their constraints. One merit of introducing the RG is that effort required in control development and calibration would be reduced. In the preceding research work by Nakada et al., only a single reference case was considered. However, it is difficult to extend the previous work to more complicated systems with multiple references such as the air path control of a diesel engine due to interference between the boosting and exhaust gas recirculation (EGR) systems. Moreover, in the air path control, multiple constraints need to be considered to ensure hardware limits.
2017-03-28
Journal Article
2017-01-0583
Farraen Mohd Azmin, Phil Mortimer, Justin Seabrook
Abstract With the introduction in Europe of drive cycles such as RDE and WLTC, transient emissions prediction is more challenging than before for passenger car applications. Transient predictions are used in the calibration optimization process to determine the cumulative cycle emissions for the purpose of meeting objectives and constraints. Predicting emissions such as soot accurately is the most difficult area, because soot emissions rise very steeply during certain transients. The method described in this paper is an evolution of prediction using a steady state global model. A dynamic model can provide the instantaneous prediction of boost and EGR that a static model cannot. Meanwhile, a static model is more accurate for steady state engine emissions. Combining these two model types allows more accurate prediction of emissions against time. A global dynamic model combines a dynamic model of the engine air path with a static DoE (Design of Experiment) emission model.
2017-03-28
Journal Article
2017-01-0603
Vicente Cuapio Espino, Akshay Bichkar, Joycer D. Osorio
Abstract Software development for automotive application requires several iterations in order to tune parameters and strategy logic to operate accordantly with optimal performance. Thus, in this paper we present an optimizer method and tool used to tune calibration parameters related to torque estimation for a hybrid automatic transmission application. This optimizer aims to minimize the time invested during the software calibration and software development phases that could take significant time in order to cover the different driving conditions under which a hybrid automatic transmission can operate. For this reason, an optimization function based on the Nelder-Mead simplex algorithm using Matlab software helps to find optimized calibration values based on a cost function (square sum error minimization).
2017-03-28
Journal Article
2017-01-0602
Vladimir Vasilije Kokotovic, Colby Buckman
Abstract With the trending electrification of vehicle accessory drives brings new control concepts useful in many cases to optimize energy management within the powertrain system. Considering that direct engine drives do not have as much flexibility as independent electric drives, it is apparent that several advantages are to be expected from electric drives. New developed high efficient electric drives can be implemented when considering many vehicle sub-systems. Combinations of continuous varying and discrete flow control devices offer thermal management opportunities across several vehicle attributes including fuel economy, drivability, performance, and cabin comfort. Often new technologies are integrated with legacy systems to deliver maximum value. Leveraging both electrical and mechanical actuators in some cases presents control challenges in optimizing energy management while delivering robust system operation.
2017-03-28
Journal Article
2017-01-0598
Mohammad Reza Amini, Meysam Razmara, Mahdi Shahbakhti
Electronic throttle control is an integral part of an engine electronic control unit (ECU) that directly affects vehicle fuel economy, drivability, and engine-out emissions by managing engine torque and air-fuel ratio through adjusting intake charge flow to the engine. The highly nonlinear dynamics of the throttle body call for nonlinear control techniques that can be implemented in real-time and are also robust to controller implementation imprecision. Discrete sliding mode control (DSMC) is a computationally efficient controller design technique which can handle systems with high degree of nonlinearity. In this paper, a generic robust discrete sliding mode controller design is proposed and experimentally verified for the throttle position tracking problem. In addition, a novel method is used to predict and incorporate the sampling and quantization imprecisions into the DSMC structure. First, a nonlinear physical model for an electromechanical throttle body is derived.
2017-03-28
Journal Article
2017-01-0596
Vittorio Ravaglioli, Federico Stola, Matteo De Cesare, Fabrizio Ponti, Stefano Sgatti
Abstract Upcoming more stringent emission regulations throughout the world pose a real challenge, especially in regard to Diesel systems for passenger cars, where the need of additional after-treatment has a big impact in terms of additional system costs and available packaging space. Therefore, the need for strategies that allow managing combustion towards lower emissions, that require a precise control of the combustion outputs, is definitely increasing. Acoustic emission of internal combustion engines contains a large amount of information related to engine behavior and working conditions. Mechanical noise and combustion noise are usually the main contributions to the noise produced by an engine. In particular, recent research from the same authors of this paper demonstrated that combustion noise can be used as an indicator of the combustion that is taking place inside the combustion chamber and therefore as a reference for the control strategy.
2017-03-28
Journal Article
2017-01-0607
Nahid Pervez, Ace Koua Kue, Adarsh Appukuttan, John Bogema, Michael Van Nieuwstadt
Abstract Designing a control system that can robustly detect faulted emission control devices under all environmental and driving conditions is a challenging task for OEMs. In order to gain confidence in the control strategy and the values of tunable parameters, the test vehicles need to be subjected to their limits during the development process. Complexity of modern powertrain systems along with the On-Board Diagnostic (OBD) monitors with multidimensional thresholds make it difficult to anticipate all the possible scenarios. Finding optimal solutions to these problems using traditional calibration processes can be time and resource intensive. A possible solution is to take a data driven calibration approach. In this method, a large amount of data is collected by collaboration of different groups working on the same powertrain. Later, the data is mined to find the optimum values of tunable parameters for the respective vehicle functions.
2017-03-28
Journal Article
2017-01-0605
Anthony D'Amato, Yan Wang, Dimitar Filev, Enrique Remes
Abstract Government regulations for fuel economy and emission standards have driven the development of technologies that improve engine performance and efficiency. These technologies are enabled by an increased number of actuators and increasingly sophisticated control algorithms. As a consequence, engine control calibration time, which entails sweeping all actuators at each speed-load point to determine the actuator combination that meets constraints and delivers ideal performance, has increased significantly. In this work we present two adaptive optimization methods, both based on an indirect adaptive control framework, which improve calibration efficiency by searching for the optimal process inputs without visiting all input combinations explicitly. The difference between the methods is implementation of the algorithm in steady-state vs dynamic operating conditions.
2017-03-28
Journal Article
2017-01-0608
Qilun Zhu, Robert Prucka, Michael Prucka, Hussein Dourra
Abstract This research proposes a control system for Spark Ignition (SI) engines with external Exhaust Gas Recirculation (EGR) based on model predictive control and a disturbance observer. The proposed Economic Nonlinear Model Predictive Controller (E-NMPC) tries to minimize fuel consumption for a number of engine cycles into the future given an Indicated Mean Effective Pressure (IMEP) tracking reference and abnormal combustion constraints like knock and combustion variability. A nonlinear optimization problem is formulated and solved in real time using Sequential Quadratic Programming (SQP) to obtain the desired control actuator set-points. An Extended Kalman Filter (EKF) based observer is applied to estimate engine states, combining both air path and cylinder dynamics. The EKF engine state(s) observer is augmented with disturbance estimation to account for modeling errors and/or sensor/actuator offset.
2017-03-28
Technical Paper
2017-01-1004
Jan Czerwinski, Pierre Comte, Norbert Heeb, Andreas Mayer, Volker Hensel
Abstract In the present paper some results of investigations of nanoparticles from five DI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, five variants of “vehicle - GPF” were investigated. These results originate from the project GasOMeP (Gasoline Organic & Metal Particulates), which focused on metal-nanoparticles (including sub 20nm) from gasoline cars with different engine technologies. The PN-emission level of the investigated GDI cars in WLTC without GPF is in the same range of magnitude very near to the actual limit value of 6.0 × 1012 #/km. With the GPF’s with better filtration quality, it is possible to lower the emissions below the future limit value of 6.0 × 1011 #/km. There is no visible nuclei mode and the ultrafine particle concentrations below 10mm are insignificant. Some of the vehicles show at constant speed operation a periodical fluctuation of the NP-emissions, as an effect of the electronic control.
2017-03-28
Technical Paper
2017-01-1009
Yajun Wang, Xingyu Liang, Yuesen Wang, Xiuxiu Sun, Hanzhengnan Yu, Xikai Liu
In this paper, the influences of metallic content of lubricating oils on diesel particles were investigated. Three lubricating oils with different levels of metallic content were used in a 2.22 Liter, two cylinders, four stroke, and direct injection diesel engine. 4.0 wt. % and 8 wt. % antioxidant and corrosion inhibitor (T202) were added into baseline lubricating oil to improve the performance respectively. Primary particle diameter distributions and particle nanostructure were compared and analyzed by Transmission Electron Microscope. The graphitization degrees of diesel particles from different lubricating oils were analyzed by Raman spectroscopy. Conclusions drawn from the experiments indicate that the metallic content increases the primary particles diameter at 1600 rpm and 2200 rpm. The primary particles diameter ranges from 5 nm to 65 nm and the distribution conformed to Gaussian distribution.
2017-03-28
Journal Article
2017-01-1005
Yizhou Zhang, Jaal Ghandhi, David Rothamer
Abstract The effect of direct-injected fuel on particle size distributions (PSDs) of particulate matter emitted from dual-fuel combustion strategies was investigated. The PSD data were acquired from a light-duty single-cylinder diesel engine operated using conventional diesel combustion (CDC) and two diesel/natural gas dual-fuel combustion strategies. Three different direct-injection (DI) fuels (diesel, 2,6,10-trimethyldodecane, and a primary reference fuel blend) and two different injector nozzles were studied. The DI fuels were chosen to have similar energy and ignition characteristics (heat of combustion and cetane number) but different physical and chemical properties (volatility, aromatics %, viscosity, density). The two nozzles (with different orifice diameter and spray angle) allowed a wide range in DI fuel quantity for the dual-fuel combustion strategies.
2017-03-28
Journal Article
2017-01-1047
Yang Liu, Yuwei Li, Tian Tian
Abstract A new ring pack model has been developed based on the curved beam finite element method. This paper describes the second part of this model: simulating oil transport around the ring pack system (two compression rings and one twin-land oil control ring (TLOCR)) through the ring-liner interfaces by solving the oil film thickness on the liner. The ring dynamics model in Part 1 calculates the inter-ring gas pressure and the ring dynamic twist which are used in the ring-liner lubrication model as boundary conditions. Therefore, only in-plane conformability is calculated to obtain the oil film thickness on the liner. Both global process, namely, the structural response of the rings to bore distortion and piston tilt, and local processes, namely, bridging and oil-lube interaction, are considered. The model was applied to a passenger car engine.
2017-03-28
Journal Article
2017-01-1043
Yang Liu, Tian Tian
Abstract A new ring pack model has been developed based on the curved beam finite element method. This paper describes the first part of this model: simulating gas pressure in different regions above piston skirt and ring dynamic behavior of two compression rings and a twin-land oil control ring. The model allows separate grid divisions to resolve ring structure dynamics, local force/pressure generation, and gas pressure distribution. Doing so enables the model to capture both global and local processes at their proper length scales. The effects of bore distortion, piston secondary motion, and groove distortion are considered. Gas flows, gas pressure distribution in the ring pack, and ring structural dynamics are coupled with ring-groove and ring-liner interactions, and an implicit scheme is employed to ensure numerical stability. The model is applied to a passenger car engine to demonstrate its ability to predict global and local effects on ring dynamics and oil transport.
2017-03-28
Journal Article
2017-01-0269
Doohyun Kim, Jason Martz, Angela Violi
Abstract The ignition delay time for direct injection compression ignition engines is determined by complex physical and chemical phenomena that prepare the injected liquid fuel for gas phase ignition. In this work, Computational Fluid Dynamics (CFD) simulations of a reacting spray within a constant volume spray chamber are conducted to investigate the relative importance of liquid fuel physical properties and oxidation chemistry on the ignition delay time. The simulations use multi-component surrogates that emulate the physical and chemical properties of petroleum-derived (Jet-A) and natural-gas-derived (S-8) jet fuels. Results from numerical experiments isolating the fuel physical property and chemistry effects show that fuel chemistry is significantly more important to ignition delay than fuel physical properties under the conditions studied.
Viewing 241 to 270 of 16480