Turbocharged engine cooling apparatus

An internal combustion engine having coolant passages therethrough, a turbocharger for increasing the density of inlet air thereto, an aftercooler for cooling the inlet air from the turbocharger and cooling apparatus comprising:

• a main coolant loop comprising a main pump, a main radiator and a main coolant conduit connecting the main pump, the coolant passages of the engine and the main radiator for unidirectional circulation of a liquid coolant;
• an aftercooler coolant loop comprising an aftercooler pump, an aftercooler radiator, an aftercooler coolant conduit connecting the aftercooler pump, the aftercooler and the aftercooler radiator for unidirectional circulation of a liquid coolant and a restricted orifice in the aftercooler coolant loop at the inlet of the aftercooler pump, the components of the aftercooler coolant loop providing a lower coolant temperature therein than the coolant temperature provided by the components of the main coolant loop therein when coolant flows of the main and aftercooler coolant loops are maintained separate;
• a first linking conduit from the aftercooler loop at the upstream side of the restricted orifice to the inlet of the main pump in the main coolant loop;
• a second linking conduit comprising a common coolant tank communicating with the inlets of both the main pump and the aftercooler pump;
• valve apparatus comprising a valve in the first linking conduit, the valve having a first condition preventing coolant flow therethrough so as to maintain coolant flows in the main and aftercooler coolant loops separate and a second condition allowing coolant flow therethrough so as to allow mixing of coolant between the main and aftercooler coolant loops;
• and
• a control responsive to an engine operation related parameter to activate the valve apparatus between its first and second conditions.