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Technical Paper

Pre-chamber Combustion System Development for an Ultra-lean Gasoline Engine

2024-04-09
2024-01-2110
Amid rising demands for fuel efficiency and emissions reduction, enhancing the thermal efficiency of gasoline engines has become imperative, which requires higher efficiency combustion strategies and integrated optimized design to maximize the work output from fuel. In gasoline engines, both increasing the compression ratio and using lean burn mode improve the thermal efficiency effectively. Although there is limited scope for increasing the compression ratio due to the higher sensitivity to knocking, especially under stoichiometric conditions, reduced sensitivity could be got with leaner mixture fill into cylinder, which can further increase the specific heat ratio and thermal efficiency. However, realizing the efficiency benefits of lean burn in gasoline engines necessitates overcoming critical challenges like ensuring robust ignition process and accelerating burning rates to achieve short, stable combustion durations.
Technical Paper

Evolution of Light-duty Gasoline Compression Ignition (LD-GCI) for High Efficiency and US Tier3- Bin30 Emissions

2024-04-09
2024-01-2092
It is widely recognized that internal combustion engines (ICE) are needed for global transport for years to come, however, demands on ICE fuel efficiency, emissions, cost, and performance are extremely challenging. Gasoline compression ignition (GCI) is one approach to achieving demanding efficiency and emissions targets. At Aramco Research Center-Detroit, an advanced, multi-cylinder GCI engine was designed and built using the latest combustion system, engine controls, and lean aftertreatment. The combustion system uses Aramco's PPCI-diffusion process for ultra-low NOx and smoke. A P2 48V mild hybrid system was integrated on the engine for braking energy recovery and improved cold starts. For robust low-load operation, a 2-step valvetrain system was used for exhaust rebreathing. The fuel injection system was a modified diesel system with high injection rate and 2000 bar pressure rating.
Technical Paper

Proactive Battery Energy Management using Navigation Information

2024-04-09
2024-01-2142
In this paper, a control strategy for state of charge (SOC) allocation using navigation data for Hybrid Electric Vehicle (HEV) propulsion systems is proposed. This algorithm dynamically defines and adjusts a SOC target as a function of distance travelled on-line, thereby enabling proactive management of the energy store in the battery. The proposed approach incorporates variances in road resistance and adheres to geolocation constraints, including ultra-low emission zones (uLEZ). The anticipated advantages are particularly pronounced during scenarios involving extensive medium-to-long journeys characterized by abrupt topological changes or the necessity for exclusive electric vehicle (EV) mode operation. This novel solution stands to significantly enhance both drivability and fuel economy outcomes.
Technical Paper

Analysis of Geo-Location Data to Understand Power and Energy Requirements for Main Battle Tanks.

2024-04-09
2024-01-2658
Tanks play a pivotal role in swiftly deploying firepower across dynamic battlefields. The core of tank mobility lies within their powertrains, driven by diesel engines or gas turbines. To better understand the benefits of each power system, this study uses geo-location data from the National Training Center (NTC) to understand the power and energy requirements from a main battle tank over an 18-day rotation. This paper details the extraction, cleaning, and analysis of the geo-location data to produce a series of representative drive cycles for an NTC rotation. These drive-cycles serve as a basis for evaluating powertrain demands, chiefly focusing on fuel efficiency. Notably, findings reveal that substantial idling periods in tank operations contribute to diesel engines exhibiting notably lower fuel consumption compared to gas turbines. Nonetheless, gas turbines present several merits over diesel engines, notably an enhanced power-to-weight ratio and superior power delivery.
Technical Paper

Modeling of the EcoCAR electric vehicle for torque split analysis and architecture selection

2024-04-09
2024-01-2166
The proliferation of electric vehicles (EVs) is making big transition in the automotive industry, promising reduced greenhouse gas emissions and improved energy efficiency. The architectural configurations and power distribution strategies necessitate the optimization of their drivability performance, all-electric ranges, and overall efficiency. This paper reports the efforts of the University of California at Riverside (UCR) EcoCAR team in EV architecture selection to match the EcoCAR EV Challenge theme of shared mobility for disadvantaged communities. The UCR EcoCAR team conducted a comprehensive analysis of various EV architectures (including rear-wheel drive, front-wheel drive, and all-wheel drive) and motor parameters, considering a spectrum of targeted vehicle technology specifications such as acceleration and braking performance, fuel economy, and cargo/passenger capacity.
Technical Paper

On the Need for Revisions of Utility Factor Curves for Plug-in Hybrids in the US

2024-04-09
2024-01-2155
Plug-in hybrid electric vehicles (PHEVs) have the capability to drive an appreciable fraction of their miles travelled on electric power from the grid, similar to battery-only electric vehicles (BEVs). However, unlike BEVs which cannot drive unless charged, PHEVs can automatically switch to gasoline power and operate similar to a regular (non-plug-in) hybrid electric vehicle (HEV). Though operating similar to HEV is already beneficial in terms of fuel economy, greenhouse gas (GHG) emissions and criteria pollutants compared to conventional internal combustion engine (ICE) vehicles, much of the attractiveness and allure of PHEVs comes from their capability to drive “almost like a BEV”, but without range anxiety about running out of battery charge.
Technical Paper

An Experimental Study on the Camshaft Impact Noise by Dynamic Coupling of Valvetrain and Chain systems

2024-04-09
2024-01-2827
To improve the fuel efficiency and satisfy the strict emission regulations, the development of internal combustion engine gets more complicated in both hardware and software perspectives, and the margins for durability and NVH quality become narrower, which could result in poor NVH robustness in harsh engine operating conditions. In this paper, we investigate experimentally the camshaft impact noise mechanism relating the valvetrain and timing chain forces to detailed motion of the camshaft and the chain tensioner. After the initial investigation of identifying the impact locations and specific engine operating points when the noise occur, the camshaft orbital motion inside of the sliding bearing are measured and visualized with the proximity sensors with calibration after sensor mounting, in addition to the chain tensioner movements.
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