Freevalve: Control and Optimization of Fully Variable Valvetrain-Enabled Combustion Strategies for High Performance Engines

Abstract

With ever stricter legislative requirements for CO2 and other exhaust emissions, significant efforts by OEMs have launched a number of different technological strategies to meet these challenges such as Battery Electric Vehicles (BEVs). However, a multiple technology approach is needed to deliver a broad portfolio of products as battery costs and supply constraints are considerable concerns hindering mass uptake of BEVs. Therefore, further investment in Internal Combustion (IC) engine technologies to meet these targets are being considered, such as lean burn gasoline technologies alongside other high efficiency concepts such as dedicated hybrid engines. Hence, it becomes of sound reason to further embrace diversity and develop complementary technologies to assist in the transition to the next generation hybrid powertrain. One such approach is to provide increased valvetrain flexibility to afford new degrees of freedom in engine operating strategies. Freevalve is an electro-hydraulic-pneumatic valve actuation system enabling independent control of IC engine valves, conceptualized by Koenigsegg's Freevalve AB. Developed primarily in line with increasingly strict emissions legislations over the past two decades, the cam-less engine technology has demonstrated significant potential, offering 20% decreased fuel consumption and 60% less cold start emissions on an average drive cycle. Adopting a software-based, data-driven, statistical approach, this paper provides a review of the most recent valve operating strategies enabled by the Fully Variable Valvetrain (FVVT) engine technology. It provides a case study for peak performance using the "Ultra Boost for Economy"(Ultraboost) project's engine as a state-of-the-art advanced valvetrain control benchmark. The One-Dimensional physics-based models are created in GT-Suite to comparatively demonstrate potential benefits of Freevalve compared to industry-standard common camshaft technologies. In addition to mitigating arising environmental concerns, preliminary findings have demonstrated that new degrees-of-freedom enabled by the FVVT IC engine technology, Freevalve, present significant potential to improve the full load curve of performance-focused engines, particularly at the low-medium engine speed range.