Electric machine, especially a generator for motor vehicles

An electric machine, particularly a generator for motor vehicles, includes a housing and a casing enclosing the housing concentrically, the casing, together with the housing, bounding an annular space that is sealed in a fluid-tight manner and is connected to a coolant outflow and a coolant inflow. To achieve a uniform circumflow of the housing with sufficient cooling capacity, even given low volumetric flow of the coolant, a plurality of axial guide bars are arranged in the annular space, so that the coolant restrictedly flows in an axially wide-strip manner through the annular space within space segments arranged in a row in the circumferential direction, with an opposing flow direction in successive space segments.