Patent ID: 7102267

Claim:
An electric machine, comprising: a housing; a rotatably supported rotor and a stationary stator which are received in the housing and interact with one another, wherein the stator has axial ends and has a stator winding which terminates in winding end parts at the axial ends of the stator; and a cooling device for cooling heat-generating components of the rotor and the stator, said cooling device including a closed-flow system having an evaporator disposed in the housing in close proximity of a one of the axial winding end parts of the stator winding, a condenser disposed outside the housing at a geodetically higher location, and a closed tube assembly, which connects the condenser and the evaporator, for circulating a coolant using a thermosiphon effect as a result of a difference in density between vapor and liquid portions of the coolant, with the closed-flow system containing a liquid-vapor mixture of the coolant in saturated state, said tube assembly including a first tube for feeding coolant to the evaporator and a second tube for conducting coolant away from the evaporator, wherein the first tube has a cross section which is smaller than a cross section of the second tube.