Water pumps: traditional, mechanically driven automotive water pumps are being revolutionized for both fuel cell and hybrid applications

摘要

Hybrid and fuel-cell vehicles present many new challenges to OE automotive water pump suppliers and systems integrators. There are potentially multiple heat sources to thermally manage to different operating temperatures. Moreover, water pumps have typically been mechanically driven from the internal combustion engine. This drive will not be available at all from fuel-cell vehicles and, due to the 'stop/start' operation proposed on many hybrid vehicles, will only be available at certain times during the drive cycle. Traditionally, automotive water pumps were mechanically driven at a constant ratio to engine speed The two defining duty points for the pump that needed to be satisfied were to supply an adequate amount of coolant to the passenger cell heater core at engine idle for windshield demist and passenger comfort, and to provide coolant flow through the engine to maintain the engine metal temperatures at full rated towing in high ambient temperature, low speed, hill climb operation. These two specification points rarely occur on the same system resistance curve, so the water pump was sized for whichever point was higher and this meant that 'over pumping' occurred during much of the water pump operating range, and therefore a significant proportion of the vehicle life.