One step closer to a radical engine for hybrid electric vehicles
The Libralato engine was invented and patented more than 20 years ago, but was never built and tested. It is a rotary engine that could address growing demand for a light, low-emissions engine for light passenger vehicles. Funded by the EU, the LIBRALATO (Libralato engine prototype) project sought to demonstrate the Libralato engine concept by building and testing a series of simulations, models and prototype engines. Project members started by constructing a 25 kW prototype engine based on the original design. Thermal and mechanical analyses revealed major mechanical design issues and that the engine would function better at lower power. To address this issue, a 50 kW prototype made up of 3 smaller rotors to provide equivalent power output was designed for tests using modelling software. Due to the lubrication management process used in the original prototype, the LIBRALATO team was not able to meet its objective of assessing, refining and optimising the performance of the 50 kW prototype, which would help to determine emissions targets for various operating conditions. It could not redesign the lubrication system and adopt selected rolling element bearings that were key to the emissions tests on the 50 kW design. As a result, few tests were carried out at the engine test facility. Using the two prototypes as a basis, a cost analysis was carried out that shows a competitive manufacturing cost of EUR 15 per kW. A market assessment indicates that the hybrid vehicle sector shows particular promise for the engine. Two patent applications have also been prepared. Despite the complications that arose, the combustion procedure was demonstrated and insight was gained on internal gas pressures. Potentially, this know-how can lead to the LIBRALATO engine concept's continuing development as a fuel- and cost-efficient breakthrough technology that meets the demands of hybrid vehicles.
Keywords
Engine, electric vehicles, Libralato, rotary engine, hybrid vehicle