Implementation and Optimization of a Variable-Speed Coolant Pump in a Powertrain Cooling System

This study investigates methods to precisely control a coolant pump in an internal combustion engine. The goal of this research is to minimize power consumption while still meeting optimal performance, reliability and durability requirements for an engine at all engine-operating conditions. This investigation achieves reduced fuel consumption, reduced emissions, and improved powertrain performance. Secondary impacts include cleaner air for the earth, reduced operating costs for the owner, and compliance with US regulatory requirements. The study utilizes mathematical modeling of the cooling system using heat transfer, pump laws, and boiling analysis to set limits to the cooling system and predict performance changes. The models are correlated with physical test data of one internal combustion engine, and a map is generated for allowable pump-speed reductions over all the conditions of engine speeds and torques, which provides insight into thermal behavior in the cooling loop and critical information to conduct optimal thermal design. It is found that speed-variable coolant pump could reduce the pump power up to 97%, and it could save the overall engine power consumption by 1.25% from the Supplemental Emission Test cycle (SET cycle), suggesting the speed-variable coolant pump is a promising technology to reduce fuel consumption and meet the emission regulations. The detailed procedure for the analysis of the cooling system is described in this study, which will provide a guideline for systematic thermal analysis and optimization of powertrain cooling systems.