Browse Topic: Drive cycles
ABSTRACT The U.S. Department of Defense faces growing fuel demand, resulting in increasing costs and compromised operational capability. In response to this issue, the Fuel Efficient Ground Vehicle Demonstrator (FED) program was initiated in order to demonstrate a tactical vehicle with significantly greater fuel efficiency than a Humvee while maintaining capability. This article provides an overview of a systems engineering methodology for maximizing fuel efficiency and its application in concept development for the FED program. Engineering tools and methods used include tradespace definition, provisional baseline product models, decomposition of energy expenditure over the product usage cycle, structured technology market surveys, complex systems modeling & simulation tools, and design space exploration / Pareto optimization. The methodology explores the impact of technology on fuel efficiency along with other aspects of vehicle development including drive cycle definition
ABSTRACT The recent climate change plan for the United States Army states that hybridized combat vehicles will enter the fleet by 2050. The Bradley Fighting Vehicle (BFV) and its family of vehicles are prime candidates for hybridization. This paper sets out to perform a drive cycle analysis for the BFV using its traditional powertrain along with hybridized powertrains. The analysis considers both series and parallel hybrid architectures, where the size of the batteries are based on modifications to the existing powertrain. Three different drive cycles are considered – stationary, highway, and off-road. The model accounts for accelerative forces, transmission losses, cooling losses, drag, road grade, tractive losses, and ancillary equipment. The results indicate that both parallel and series hybrids provide reduced fuel consumption and increased range. Of the two, the series hybrid architecture provides more overall benefits. The study concludes by discussion of the technical challenges
Abstract This paper presents the development of a transmission-in-the-loop (TiL) experimentation system. In this TiL experimental setup, the input side of the transmission is controlled by a dynamometer emulating the engine, while the output sides of the transmission are controlled by two dynamometers emulating the wheels and vehicle. The models emulating these vehicle components are required to possess sufficient fidelity to simulate engine torque pulse (ETP) and wheel slip dynamics while being computationally efficient to run in real-time. While complex engine and tire models exist in the literature that accurately capture these dynamics, they are often too numerically stiff for real-time simulation. This paper presents the system level details of such a TiL setup, and the modeling concepts for the development of high fidelity real-time models of the engine and tire dynamics for use in this experiment. Parameters of the engine model are identified using experimental data. Vehicle
Nowadays, Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) are becoming popular globally due to increasing pollution levels in the environment and expensive conventional non-renewable fuels. Li-ion battery EV’s have gained attention because of their higher specific energy density, better power density and thermal stability as compared to other cell chemistries. Performance of the Li-ion battery is affected by temperatures of the cells. For Li-ion cells, optimum operating temperature range should be between 15-35 °C [1]. Initially, small battery packs which are cooled by air were used but nowadays, large battery packs with high power output capacities being used in EV’s for higher vehicle performance. Air based cooling system is not sufficient for such batteries, hence, liquid coolant based cooling systems are being introduced in EV’s. Computational Fluid Dynamics (CFD) simulation can be used to get better insight of cell temperature inside battery. But it is complex, time
Homologation is an important process in vehicle development and aerodynamics a main data contributor. The process is heavily interconnected: Production planning defines the available assemblies. Construction defines their parts and features. Sales defines the assemblies offered in different markets, where Legislation defines the rules applicable to homologation. Control engineers define the behavior of active, aerodynamically relevant components. Wind tunnels are the main test tool for the homologation, accompanied by surface-area measurement systems. Mechanics support these test operations. The prototype management provides test vehicles, while parts come from various production and prototyping sources and are stored and commissioned by logistics. Several phases of this complex process share the same context: Production timelines for assemblies and parts for each chassis-engine package define which drag coefficients or drag coefficient contributions shall be determined. Absolute and
On the path to decarbonizing road transport, electric commercial vehicles will play a significant role. The first applications were directed to the smaller trucks for distribution traffic with relatively moderate driving and range requirements. Meanwhile, the first generation of a complete portfolio of truck sizes has been developed and is available on the market. In these early applications, many compromises were made to overcome component availability, but today, the supply chain has evolved to address the specific needs of electric trucks. With that, optimization toward higher performance and lower costs is moving to the next level. For long-haul trucks, efficiency is a driving factor for the total cost of ownership (TCO) due to the importance of the energy costs [1]. Besides the propulsion system, other related systems must be optimized for higher efficiency. This includes thermal management since the thermal management components consume energy and have a direct impact on the
In response to global climate change, there is a widespread push to reduce carbon emissions in the transportation sector. For the difficult to decarbonize heavy-duty (HD) vehicle sector, hybridization and lower carbon-intensity fuels can offer a low-cost, near-term solution for CO2 reduction. The use of natural gas can provide such an alternative for HD vehicles while the increasing availability of renewable natural gas affords the opportunity for much deeper reductions in net-CO2 emissions. With this in consideration, the US National Renewable Energy Laboratory launched the Natural Gas Vehicle Research and Development Project to stimulate advancements in technology and availability of natural gas vehicles. As part of this program, Southwest Research Institute developed a hybrid-electric medium-HD vehicle (class 6) to demonstrate a substantial CO2 reduction over the baseline diesel vehicle and ultra-low NOx emissions. The development included the conversion of a 5.2 L diesel engine to
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