In automobile design, a rear-engine layout mainly espoused for small entry-level cars and light commercial vehicles for three reasons - packaging, traction, and ease of manufacturing. The aim of this paper is to strategize cooling system of rear-mounted engine of a small gasoline car. Radiator and cooling fan packaged close to engine at rear of the car for simple packaging. Efficient thermal management ensured by robust overheat protection stratagem using EMS software.
DFSS, a disciplined problem prevention approach that helps in achieving the most optimum design solution and provides improved and cost effective quality products; is used to finalize an optimum design based on the analysis of the various tests carried out as per DOE [1]. This paper is about designing a distinctive cooling system of a car having rear-mounted engine with rear radiator but front mounted HVAC system [2].
Strategizing overheat protection for subject vehicle is crucial due to three critical reasons which tempt high probability of engine overheating. (1) The arrangement having HVAC system mounted at front requires lengthy coolant lines extending from engine (rear of the car) to the HVAC heater (front of the car). The underbody assembly of heater lines are prone to structural damage thus leading to overheating. (2) Lengthy coolant lines of HVAC heater system becomes critical as air prone to trap in the coolant system during coolant filling and de-aeration process leading to overheating. (3) In case of radiator fan failure, rear mounted engine compartment does not get enough surrounding air for cooling and will lead to overheating.
This final design provide compact packaging of coolant system, ensure better thermal management and maintain good aesthetics of the automobile. The serviceability of the engine i.e. filling of the coolant and process of de-aeration also simplified with the finalized design.
This paper also comprise a robust engine protection EMS (Engine Management System) function in case of overheat phenomenon. The strategy validated on fleet cars and it meets safety critical requirements to protect engine and critical components from damage. This novel FIVE LEVEL monitoring strategy ensures protection of vehicle and components in the event of cooling system failure.