Analysis of fuel economy of mild hybrid vehicle by the backward simulation with considering power loss of oil pump

The idle stop and go(ISG) function, which automatically turns off the engine at the time of stopping, is currently applied to a hybrid vehicle in order to increase the transmission economy. This function turns off the engine when the vehicle is stopped. It helps to improve the fuel efficiency by reducing fuel waste by idling. However, if you turn off the engine at a stop, the mechanical oil pump(MOP) and the flow will also stop. For this reason, the flow rate required for the power circulation is supplied through the electric oil pump(EOP), and power loss occurs. Power loss through the use of additional oil pumps affects fuel economy, as well as the capacity of the oil pump used. Therefore, power loss through the use of an oil pump must be considered in a fuel economy analysis. In this study, the fuel consumption analysis was performed while considering the power loss of the oil pump by using the backward simulation. To do this, we modeled a hypothetical mild hybrid vehicle and proceeded in assuming a hydraulic line. The study is based on the analysis of the fuel consumption reduction of the vehicle model with the idle stop and go function disregarding the oil pump loss, and the vehicle model using the mechanical oil pump and the electric oil pump. We also analyzed the changes in the engine and motor operating points.