Advanced Thermal Management for Internal Combustion Engines - Valve Design, Component Testing and Block Redesign 2006-01-1232
Advanced engine cooling systems can enhance the combustion environment, increase fuel efficiency, and reduce tailpipe emissions with less parasitic engine load. The introduction of computer controlled electro-mechanical valves, radiator fans, and coolant pumps require mathematic models and real time algorithms to implement intelligent thermal control strategies for prescribed engine temperature tracking. Smart butterfly valves can replace the traditional wax-based thermostat to control the coolant flow based on both engine temperature and operating conditions. The electric water pump and radiator fan replace the mechanically driven components to reduce unnecessary engine loads at high speeds and provide better cooling at low speeds. However, implementation of electro-mechanical actuators including the alternator and electrical storage devices introduces inefficiencies in mechanical to electrical energy conversion (and electrical to mechanical energy conversion), which may require increased fuel consumption over pure mechanical components. Empirical models can provide realistic component data used in simulation tools during the development process, and also define the basis for cooling system control algorithms. In this paper, a general framework to derive these empirical models is investigated for thermal management systems where the engine temperature must be accurately controlled in both steady state and transient operation. The evolution of automotive cooling systems also requires a paradigm shift in the engine block design. The design changes include isolated cylinder water jackets, temperature sensor arrays, and distributed smart valves to enable distinct cylinder-by-cylinder temperature maintenance for optimum combustion. This paper explores the introduction of a ‘coolant rail’ to accommodate specific cylinder temperature control defined by an on-demand cylinder dependent cooling strategy.