Abstract
Keywords - Diesel - Engine - Two-Stage Turbo-Charging - Electrical Assistance - Fuel Consumption
ABSTRACT - The future challenges for modern engines are the reduction of exhaust emissions and fuel consumption. The legislative, the performance and emissions requirements of the new automotive engines demand therefore the development of new technologies to purpose downsized applications to reach an average CO2 emissions level of 140g/km in 2008.
This article presents two applications performed by Renault which concern :
- Development of an application with a Two-Stage Turbo-Charging System.
- Development of a vehicle equipped with a small diesel engine electrically assisted.
Two-Stage Turbo-Charging.
The first example of diesel downsizing, shows the potential of the adaptation of a Two- Stage Turbo-Charging system, on a 1.5 L engine, which allows to reach, for the same level of global customer requirements, a reduction of the consumption.
In this study, we will present the numerical optimisations made with different combinations of turbochargers. We will present the results obtained on the test bench that allow to validate the vehicle simulations results.
This study shows that the specific management of the regulation of the turbochargers is necessary to reach the objectives of power of 103 kW at 4000 rpm and torque of 320 N.m at 2000 rpm corresponding to the 2L engine reference target.
Vehicle Electrically Assisted.
The second example of downsizing concerns the electrical assistance.
This support based on a Laguna car equipped with a 1,5 L engine allows to show a significant reduction of the consumption with the same level of global customers requirements of the reference 1.9L engine.
The vehicle is equipped with a separated starter generator, pulled by belt, a specific power electronic system, a energy storage (battery or super-capacity ), a 42 V network. The electric assistance of the small diesel engine allows to fill the deficit of torque at low engine speed and to improve the engine power in different functioning areas.
The prototype is equipped with a specific supervision system which allows a "intelligent" management of the engine due to the integration of the « Energy Management Rules » numerically developed by the optimisation of the working points of the engine. This energy management is based on Stop and Start, Brake and Boost strategies allowing to reduce the consumption and the emissions.