traction system comprising an electric motor and an outside liquid-air heat exchanger for cooling the rotor

A traction system for a railway vehicle, comprising:

• an electric motor comprising a stator, a rotor adapted for rotating with respect to the stator about an axis, and a housing including a peripheral part surrounding the stator about the axis, the peripheral part being in thermal contact with the stator for receiving heat from the stator, the housing, the rotor and the stator defining two chambers axially opposite each other, the rotor defining a plurality of air passages between the two chambers, the peripheral part defining a first liquid circuit configured for receiving a first flow of cooling liquid intended to be heated by said heat received from the stator,
• a heat exchanger located outside of the housing, and having an air inlet in fluid communication with one of the two chambers, an air outlet in fluid communication with the other of the two chambers, and a second liquid circuit configured for receiving a second flow of cooling liquid, the air passages, the two chambers and the heat exchanger defining an air loop adapted for cooling the rotor, the heat exchanger being adapted for performing a heat exchange between air of the air loop and the second flow of cooling liquid, and
• a fan for circulating air in the air loop.