THERMAL EXPANSION TANK HAVING AN EXPANSION MEMBER FOR USE IN A DIELECTRIC FLUID COOLING CIRCUIT

A cooling system for an electrified vehicle powertrain includes a cooling circuit fluidly coupling at least a traction battery, an electric motor, a pump, a heat exchange device and an expansion and contraction tank. The tank provides a sealed volume in the circuit for thermal expansion and contraction of the dielectric fluid as the temperature of the dielectric fluid increases or decreases. The tank includes an elastic member bifurcating an interior volume of the tank and separating the dielectric fluid on one side of the bladder from a volume of air functioning as a fluid spring on the other side of the bladder. The gas is configured to compress with the thermal expansion of the dielectric fluid.