A Study on Gasoline Direct Injection (GDI) Pump System Performance using Model-Based Simulation

Abstract

This paper focuses on a simulation study of a newly developed high-pressure fuel pump system for small engine. When an engine is operated at high speed in a typical Gasoline Direct Injection (GDI) system, its pump will perform extra pumping requiring continuous engine work. Because it is driven by the engine’s camshaft, the extra pumping action is both unavoidable and parasitic. In this study, a new GDI pump has been designed and built to only operate at a constant speed, regardless of engine load and speed. The pump is driven by an electric motor via a camshaft and is intended for a four-stroke, 0.2 litre, single-cylinder, spark ignition engine. The electric motor is governed by a control unit called the Engine Control Unit (ECU). The GDI pump will supply fuel to a rail up to its maximum pressure capacity. The pump is developed in accordance with a physical model-based design approach and is simulated using Matlab- SimscapeTM. Based on the calculation and simulation performed, the designed pump pressure is capable of producing discharge exceeding 4.5 MPa. Theoretical calculation also shows that the pressure developed by the pump reaches 10.54 MPa when a two lobe cam is used. In addition, the pressure developed by the pump is recorded to be 11.15 MPa, with an error of 5.8 % when a similar condition is applied to the physical modelling.