Experimentally Based Methodology to Evaluate Fuel Saving and CO 2 Reduction of Electrical Engine Cooling Pump during Real Driving

Abstract

Engine thermal management (ETM) is a promising technology that allows the reduction of harmful emissions and fuel consumption when the internal combustion engine (ICE) is started from a cold state. The key technology for ETM is the decoupling of the cooling pump from the crankshaft and the actuation of the pump independently. In this article, an electric engine cooling pump has been designed through a novel experimentally based procedure and operated on a vehicle equipped with an advanced turbocharged gasoline engine, particularly interesting for its hybridization potential. In the first phase, a dedicated experimental campaign was conducted off board on an engine identical to the one equipped in the vehicle to assess the characteristics of the cooling circuit and the reference pump performances. The experimental data have been used to design an electric pump with a best efficiency point (BEP) located in a region more representative of the real operating conditions faced by the vehicle during real driving. Once prototyped, the electric pump has been compared to the reference mechanical one on a real driving mission profile whose parameters have been experimentally evaluated. The comparison was made in the same operating conditions of flow rate and the pressure head acting on the revolution speed of the prototype to focus the attention on the effect of the different design choices made possible by the electric actuation. The procedure can evaluate the pump-related fuel consumption, whatever the real vehicle speed profile and the actuation of the pump. The results show that in a driving cycle with urban, extra-urban, and highway phases, the electric pump absorbs 66% less power compared to the mechanical one, which translates into a 0.55 gCO2/km specific emission reduction. This demonstrates the validity of the novel design procedure together with the benefits of the electric actuation.