Experimental Procedure for Measuring the Energy Consumption of IC Engine Lubricating Pumps during a NEDC Driving Cycle

The paper presents an experimental procedure for comparing different families of IC Engine lubricating pumps in terms of total consumed energy in a NEDC driving cycle. Measures are performed on a test rig able to reproduce the oil temperature profile, the lubrication circuit permeability and its variation during the engine warm-up. The pump under test is driven by a variable speed electric motor supplying the engine velocity profile of the driving cycle. The load on the pump is generated by means of a variable restrictor controlled in a closed loop by a proper combination of speed, temperature, flow rate and pressure signals in order to replicate the typical permeability of the lubricating circuit. The method has been applied to a 15 cc/rev crankshaft mounted gerotor pump for a medium displacement Diesel engine; the flow-pressure characteristics of the lubricating circuit at different temperatures and the oil heating rate measured on the engine have been supplied to the test rig control system. The reference pump has been contrasted with a crankshaft mounted variable displacement vane pump with absolute pressure limiter device and an off-axis external gear pump with the same displacement and pressure setting. Experimental tests bring to evidence the advantage of the variable displacement pump during short trips with cold start, while the external gear pump prevails at the end of NEDC cycle where highest engine speeds and oil temperatures are reached.