Abstract
Energy economy in automotive field should be applied to every power consumer in the auxiliary systems, mainly to mechanically driven aggregates such as cooling fan. The procedure of dimensioning the cooling system on the heat released at rated power turn to be obsolete as the concept of continuously driving fan is faded. The fan drive consumes unnecessary energy in different operation modes such as starting, warming-up and low loads. The engine manufacturers intend to limit the fan power loss designing intermittent driven and variable-speed fans, especially for heavy duty vehicles and equipment. The paper studies the increase of performance of a heavy duty diesel engine when the cooling fan is driven discontinuously. For the turbocharged 1035 L6 DT (233 HP) diesel engine manufactured at ROMAN truck factory there were presented dynamometric tests for three equipment versions of the engine, performed at Road Vehicle Institute (INAR): with the series fan, with a viscous fan and with a blocked viscous fan. There were investigated the air flow rates driven by the fan versus pressure loss, at constant speeds, the fan consumed power versus speed and efficiency. Other investigated indicator for engine development is engine thermal constant. The results showed at rated speed (2200 rpm) when using a viscous fan, that the power consumption during starting, warming and operating in cold weather will require only 3% of the power consumption in continuous drive of the cooling fan. The experiments confirmed the requirements for controlled drive of cooling fan to heavy duty commercial vehicles as it is already used in passenger car development.
Keywords: diesel engine, cooling fan, variable speed drive