Study On The Control Strategy And Experiment Of Diesel/natural Gas Dual-fuel Engine

The situation of the increasingly serious oil shortage and environmental pollution impels governments,scholars and enterprises around the world to develop cleaner and more efficient alternative fuels for internal combustion engine. Natural gas has become the most promising alternative fuel in the field of transportation in 21 st century due to its abundant reserve, attractive price, extremely low emissions and excellent knock resistance characteristics. The mature solution of the natural gas employed in internal combustion engine is spark-ignited engine. Some scholars propose that natural gas can be employed in compression-ignited engine for bringing natural gas’ s superiority of high-octane rating into full play.Natural gas is used as primary fuel and induced into manifold, and then natural gas-air mixture is ignited by a very small amount pilot diesel which is directly injected into cylinder at the end of the compression stroke.This kind of engine has attracted great attention from academia and enterprises because of its good dynamic performance, extremely low emissions on NOx and PM.In this study, a common-rail turbo charged diesel engine was converted to operate in duel-fuel mode by adding natural gas injection system, in which natural gas was sequentially injected into manifold. And developed a electronic control system for the converted duel-fuel engine. Introduced the hardware structure,main functions of duel-fuel ECU and the functions, principles of key sensors and actuators which constitute the electronic control system.A duel-fuel engine control strategy was put forward, which was based on the original diesel injection signals real-time acquisition and equivalent heat value substitution. On the one hand, this strategy could preserve the ability to work under the original diesel mode. On the other hand, this strategy could make maximum use of the mature algorithms to calculate the amount of diesel and natural gas depending on original real-time diesel injection signals under current working conditions.At last, the strategy and duel-fuel ECU was verified by experiments. The experiment results show that the duel-fuel ECU schematic is correct and complete, satisfy the design requirements has high application values. Comparison tests were finished on the engine full-load characteristic and emissions performance under two working mode.