Thermal expansion tank having an expansion member for use in a dielectric fluid cooling circuit

An electric vehicle cooling system using dielectric cooling fluid, the cooling system comprising:

• a cooling circuit fluidly coupling at least a traction battery, an electric motor, a fluid pump, a heat exchange device and an expansion and contraction tank;
• wherein the cooling circuit is a closed circuit sealed from the atmosphere and at least substantially free of atmospheric air;
• wherein the pump circulates the dielectric fluid through the cooling circuit for cooling at least the traction battery and the electric motor;
• wherein the expansion and contraction tank is configured to provide a sealed volume in the cooling circuit to allow for thermal expansion of the dielectric fluid as the temperature of the dielectric fluid increases with increasing temperature of one or more of at least the traction battery and electric motor;
• wherein the expansion and contraction tank includes an expansion member bifurcating an internal volume of the expansion and contraction tank into a first portion on one side of the expansion member in communication with the dielectric fluid, and second portion on an opposite side of the expansion member, the expansion member providing a seal between the first and second portions;
• and
• wherein the second portion comprises a gas that is configured to compress within the second portion of the tank with the thermal expansion of the dielectric fluid in the first portion.