Study of the combustion system of a new small DI diesel engine with advanced common-rail injection system

摘要

In-cylinder combustion phenomena, performance and emissions of a new single-cylinder (225 cm{sup}3) naturally aspirated DI diesel engine, with an advanced low-cost, common-rail system for multiple injections, were investigated. The main objective of the present work was the study of the combustion system in terms of combustion chamber geometry, spray angle and number, injections pressure as well as injections number per engine cycle to find the best compromise between smoke and NO{sub}x emissions. CFD simulations were made to optimize the combustion chamber shape and the spray angle of a 6 holes nozzle to control the in-cylinder soot formation. The common-rail (CR) system consisted of an in-house modified low-cost PF Bosch injection unit for pumping the fuel up to 60 MPa, a high-pressure accumulator (rail) equipped with a pressure regulator valve and sensor as well as improved fast electronic drivers to drive both the pressure regulator valve and a commercial solenoid injector. A programmable electronic control unit (PECU) based on a dSpace processor was used to manage the fuel injection system in terms of injection pressure, start of injection, number of injections for engine cycle, duration of each injection as well as the dwell time between consecutive injections.