Development of an electrically driven diesel fuel pump for commercial vehicles using HILS

Abstract

Common-rail fuel injection systems on modern diesel engines have fuel pumps that are mechanically driven by the crankshaft. The pumps actually house two pumping elements: a low pressure element and a high pressure element. Part of the fuel compressed by the low pressure element returns to the tank in the process of maintaining the pressure in the common-rail at adequate levels for injection. Since the returning fuel represents pumping energy loss, fuel economy improves if the returned fuel can be reduced by using a properly controlled electrical fuel pump. As the first step in developing an electrical fuel pump the fuel supply system on a six-liter diesel engine was modeled with AMESim to analyze the workload and the fuel feed rate of the injection pump; the results served as the basis for selecting a suitable servo-motor to drive the pump. A motor controller was built using a DSP and a program which controls the common-rail pressure using a proportional control method based on the target fuel pressure information from the engine ECU. Test equipment was also fabricated to evaluate the performance of the electrically driven fuel pump. In a simulated vehicle test during the first 200 seconds of the NEDC driving schedule, the electric pump satisfied the fuel pressure and flow demand of the engine, consuming only 48.3% of the energy that an engine-driven pump would require.