Potential of hybrid powertrains in a variable compression ratio downsized turbocharged VVA Spark Ignition engine

• Published in: Energy (Oxford) 2020-03, Vol.195, p.117039, Article 117039
• Main Authors: García, Antonio, Monsalve-Serrano, Javier, Martínez-Boggio, Santiago, Wittek, Karsten
• Format: Article
• Language: English
• Subjects: Air pollution; Automobiles; Carbon dioxide; Carbon dioxide emissions; Compression; Computer simulation; Design of experiments; Diesel engines; Downsized combustion engines; Driving cycles; Electric motors; Electric vehicles; Electrification; Emissions; Emissions regulations; Engine tests; Exhaust pipes; Fuel consumption; Hybrid electric vehicles; Hybrid powertrain; Internal combustion engines; Legislation; Light duty vehicles; Optimization; Passengers; Pollutants; Powertrain; Spark ignition; Superchargers; Variable compression ratio
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2020.117039

After the diesel emissions scandal, also known as Dieselgate, Direct Injection Spark-Ignited (DISI) internal combustion engines (ICE) appears as the most promising alternative to mitigate the harmful tailpipe emissions from passenger cars. In spite of that, the current ICE technologies are not enough to achieve the fuel consumption/CO2 emissions targets set by the new transportation legislation (4.1 Lgasoline/100 km, 95 gCO2/km for 2021). In this complex scenario, the electrification of the powertrain using high efficiency electric motors and battery package together with sophisticated DISI engines appears as potential solution to meet these requirements. The aim of this work is to study the fuel consumption and pollutant emissions in transient conditions from a passenger car equipped with a variable compression ratio (VCR) DISI engine and electrified powertrain technologies. The vehicle behavior was simulated by means of a 0D GT-Suite model fed by experimental results obtained in an engine test bench. Mild hybrid electric vehicle (MHEV) and full hybrid electric vehicle (FHEV) architectures using a VCR DISI engine were studied. Moreover, an optimization methodology is presented to select the best vehicle configuration in terms of hardware and control strategies by means of a design of experiments (DoE). The results show that VCR allows a fuel improvement of 3% with respect to the conventional DISI fixed CR along the worldwide harmonized light vehicles test cycles (WLTC). The benefits found when combining the VCR technology with hybrid powertrains are even higher. In this sense, the fuel improvements were higher as the electrification levels increased, with 8% for MHEV-VCR and around 20% for FHEV-VCR. In terms of emissions, the two clear benefits with FHEV-VCR were the reduction of particle number (PN) and unburned hydrocarbons (HC) of around 60% and 15%, respectively, as compared to the conventional DISI. •VCR hybrid technology evaluated in transient conditions through vehicle simulations.•The VCR system allows fuel improvements of 3% in conventional powertrains.•VCR system allows fuel improvements of 8% in mild and 18% in full hybrid powertrains.•VCR hybrid allows to increase the engine efficiency from 29% to 36% in a WLTC.•VCR full hybrid leads to the lowest fuel consumption in real driving conditions.