Abstract
Worldwide fuel consumption regulations are becoming more and more stringent. As a result, car companies are looking at a wide portfolio of component technologies, including engines, transmissions, and electrification. This study examined fuel consumption reductions offered by a collection of advanced spark-ignition (SI) engine technologies using full-vehicle simulations. High-fidelity engine models were developed to simulate Variable Valve Lift (VVL), Turbocharging and Downsizing (T), and Gasoline Direct Injection (DI) technologies in an incremental manner through an accumulative technology pathway. Measurements from these models were used to build full-vehicle simulations for each of the technologies across a spectrum of vehicle powertrain configurations with increased electrification. Each vehicle component was algorithmically sized to meet common performance criteria to ensure uniformity and comparability. The effects of vehicle hybridization and electrification on the technology fuel reductions while transitioning from conventional to mild, full, and plug-in hybrid configurations were investigated. Conventional vehicles were found to attain the highest overall benefits, while mild and full hybrid vehicles attained lower benefits. A negative correlation was found between engine technology benefit and vehicle hybridization. Over the pathway, cycles, and configurations investigated, average benefits for DI were found to be 8.0%; VVL, 3.4%; Turbocharging and downsizing, 9.7%; and downsizing from 1.6 L to 1.2 L, 2.7%.
Highlights
Since the creation of the gasoline-fueled automobile, the spark-ignition (SI) internal combustion engine has remained one of the most inefficient components of the vehicle powertrain, limited by the inherent nature of thermodynamics and the Otto Cycle
The advanced engine technologies investigated in the study were Variable Valve Lift (VVL), Turbocharging and Downsizing (T), and Gasoline Direct Injection (DI)
Results from the simulated vehicles indicate that conventional and mild hybrid vehicles, where the engine is directly coupled to the road load and responsible for tractive torque, saw higher benefits compared to the full hybrids
Summary
Since the creation of the gasoline-fueled automobile, the spark-ignition (SI) internal combustion engine has remained one of the most inefficient components of the vehicle powertrain, limited by the inherent nature of thermodynamics and the Otto Cycle. To achieve the highest overall vehicle efficiency, the internal combustion engine must be designed and controlled to approach the theoretical maximum efficiency offered by thermodynamics. To this end, much progress has been made in the past several decades creating advanced engine technologies that alter the thermodynamic cycle of combustion engines to reduce pumping losses, increase compression ratios etc. Previous studies have employed several analytical methods, EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium such as Lumped Parameter Models and Partial Discrete Approximation, to estimate the fuel consumption benefits resulting from increasing the level of internal combustion engine technology[5]. The main drawback of such methods is their reliance on estimates of the synergies among technologies and their inability to account for the specific operating conditions experienced by the wide spectrum of vehicle powertrain configurations
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