Fuel injection rate shaping and its effect on spray parameters in a direct-injection gasoline system

Abstract

Abstract The presented test results contain an analysis of the variable control of fuel flow from high-pressure gasoline injectors. To control such a system, the cRIO 9063 system and NI-driven module were used. This system allows controlling a piezoelectric injector with a time-varying needle height, which affects the time-varying fuel flow during a single-time opening of the injector needle. The tests were carried out in a constant volume chamber with a constant fuel dose (Pinj = 15 MPa and qo = 17.4 mg), with two values of medium back pressure: Pb = 1.0 and 1.5 MPa as well as different injector opening times (resulting from equal doses of fuel). Analyzes of changes in linear and radial fuel spray range as well as the fuel spray volume were made. It has been found that injection rate-shaping allows to control the fuel flow from the injector at a variable needle height. A reduction of the linear range of the spray by 50% and a radial range by 40% compared to conventional settings within a specified time from the start of the injection was achieved. The surface area of the spray is limited by a maximum of 60% compared to the settings at the maximum control voltage. The use of injection rate-shaping may be an effective method of controlling the variable fuel flow from the injector and may allow the replacement of multi-stage fuel injection. Graphical Abstract