COOLING AND PREHEATING PROCESS AND SYSTEM

The invention concerns a device and method for cooling and preheating, especially of transmission fluid, of an internal combustion engine, with an equalization tank, with at least one radiator, which can be connected by means of an engine thermostat when a predetermined temperature is reached in the cooling loop, and with a water/oil heat exchanger. It is prescribed according to the invention that the forward stream (1) of a single water/oil heat exchanger (5) be branched off in the heating phase by means of a valve unit (3) essentially from the main cooling loop (12) of the internal combustion engine (17) and that its forward stream (1) in the cooling phase be taken by means of the same valve unit (3) essentially in the coolant side stream (13) from the low-temperature region (14) of the radiator (4) or a separate low-temperature cooler (14a) connected in the side stream after radiator (4, 4a). The method proposes that the forward stream (1) of the water/oil heat exchanger (5) be taken in the heating phase essentially from the main coolant stream (12) not flowing through the radiator (4), that switching to cooling operation occur at a temperature lying somewhat below the switch point of the engine main thermostat (9) and the forward stream (1) of the water/oil heat exchanger (5) in cooling operation be branched off essentially from the low-temperature region (14) of radiator (4), or from a low-temperature cooler (14a) additionally connected in the side stream after radiator (4, 4a).