Cooler plate for a new hybrid diesel electric rail car
Modifying a diesel mechanic to become a hybrid diesel electric rail car
In a joint research project Deutsche Bahn and Tognum MTU have modified a diesel mechanic to become a hybrid diesel electric rail car.
Images courtesy of TOGNUM AG
Energy savings on track with many stops and slopes
The new hybrid train is currently in operation in the Maintal valley on a track that has lots of stops and ascending and downward slopes making it especially suitable for energy savings. In braking and downhill drive electric energy is recuperated and stored to a battery which is then used to aid propulsion when accelerating after a stop or on uphill slopes.
Mechanical and cooling requirements for hybrid pack
The hybrid power pack is mounted to a cooler plate supplied by AMS Technologies. Cooler plate and power electronics exceed 120 kg in weight such that a rugged construction was required. A common make of an aluminum plate with press lock type inserted tubes was excluded due to the risk that thermal cycling of maximum heat loads of 5 kW could cause degradation of the joint of the tube along the long cooler plate of 1.2 m. Power electronics in rolling stock applications must withstand many 10s of thousands of thermal cycles.
Thermal design flexibility and ruggedness of friction stir weld aluminum cooler plate
A fluid channel geometry machined into an aluminum plate was finally chosen. It is sealed by a cover welded into the main plate utilizing friction stir welding technology. Our friction stir welds have proven to withstand millions of pressure cycles without signs of fatigue and maximum pressures of up 140 bars without being destroyed.
"Water cooling of power electronics was kind of new for us, so we were happy to have a partner with expertise in both water cooling and rolling stock requirements", Matthias Herold, Project manager, Tognum-MTU Friedrichshafen.
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