Development of basic methodologies for the construction of an innovative single-cylinder engine for two-wheeled vehicles with low consumption and low environmental impact, which can be implemented on chassis in advanced materials for high performance
FIRB Project
Call: Idee progettuali relativamente ai grandi programmi strategici previsti dal PNR 2005-2007
Project code: RBIP063PM5
- Scientific Responsible: Giglio Veniero
- Participants: Costa Michela, di Gaeta Alessandro, Iorio Biagio, Police Giuseppe, Rispoli Natale, Sgammato Bruno, Cecere Michele, Reale Fabrizio.
Period 2008 – 2011
The project objective is the development of methodologies useful for the realization of a high performance motorcycle engine, featured by low consumption and low emission, compatible with future emission standards. The reference engine is a single cylinder with a 0.65 liter total swept volume, with high bore and short stroke so as to allow high revolution speed while maintaining reasonable average piston speed. In comparison with a multi-cylinder engine with same total displacement, a lower friction surface and a lower dead volume result, with noticeable benefit on mechanical efficiency at high speed. The main innovative features of the engine project are:
- High volumetric compression ratio and high EGR rate
- Gasoline direct injection, with an injection system capable of two injections per cycle
- Use of a flexible mechanical variable valve timing device
- Stoichiometric fueling with three way catalyst and UEGO sensor
- Use of innovative sensors and closed loop controls for ignition optimization avoiding knock
- Model based control of air to fuel ratio
The engine is designed so as to work in stoichiometric condition (in urban cycle), currently the most efficient way for emission abatement. However, without adequate strategies of combustion process management, such a system involves limitations of the overall engine efficiency and a knock propensity which inhibit high efficiencies.
The external cooled EGR allows a dilution of the mixture in the combustion chamber while maintaining a stoichiometric ratio between fresh air charge and fuel, averting knock possibility and reducing nitric oxides. A double injection would allow a cooling of mixture, with cylinder filling enhancement, concurring to avoid knock and to the robustness of the combustion process, featured by charge stratification. A flexible valvetrain management allows to optimize engine filling in whatever working condition, significantly reducing pumping losses.
The work was divided into three tasks:
1. The preliminary project of the combustion chamber, aimed to the optimization of in-cylinder air motion and injector location, with the evaluation of the possibility of a double injection in the different operating conditions, and the choice of the start and duration of injection
2. Design of the valvetrain system, with kinematics analysis and optimization of valve opening and closing strategies using a mechanical flexible variable valve timing device.
3. Development of a system for combustion diagnostics based on the use of a usual spark plug as a ionization current sensor. Such a system, entirely designed and realized at Istituto Motori, has been particularly aimed to knock detection, resulting as an effective alternative to conventional piezo-quartz sensors mounted into the combustion chamber.