Reduced Piston Oil Cooling for Improved Heavy-Duty Vehicle Fuel Economy

Increased electrification of future heavy-duty engines and vehicles can enable many new technologies to improve efficiency. Electrified oil pumps are one such technology that provides the ability to reduce or turn off the piston oil cooling jets and simultaneously reduce the oil pump flow to account for the reduced flow rate required. This can reduce parasitic losses and improve overall engine efficiency. In order to study the potential impact of reduced oil cooling, a GT-Power engine model prediction of piston temperature was calibrated based on measured piston temperatures from a wireless telemetry system. A simulation was run in which the piston oil cooling was controlled to target a safe piston surface temperature and the resulting reduction in oil cooling was determined. With reduced oil cooling, engine BSFC improved by 0.2-0.8% compared to the baseline with full oil cooling, due to reduced heat transfer from the elevated piston temperatures. A GT-Drive vehicle model was used to evaluate the potential of this technology on a heavy-duty vehicle over various drive cycles. The parasitic losses of the engine oil pump were removed from the engine fuel efficiency map, and electric pump was added to the vehicle model. The pump flow rate was optimized to match the requirements of the engine at any given speed and load condition. The oil pump flow rate was further optimized based on the amount of piston oil cooling reduction possible at each operating point. The model was exercised over four drive cycles and vehicle fuel economy was observed. Results for the simulation showed that an electrified oil pump combined with reduced piston oil cooling provided an average fuel economy improvement of 2.7% over the baseline vehicle.