Thermal management of urea dosing components in an engine exhaust after-treatment system

An internal combustion engine comprising:

• combustion chambers within which fuel is combusted to operate the engine;
• a cooling system, including a coolant pump, for circulating liquid coolant through the engine;
• an exhaust system through which products of combustion that include NOx are conveyed from the combustion chambers to atmosphere, including an SCR catalyst for chemically converting NOx to other products in the presence of urea introduced into the exhaust system;
• a tank for holding a supply of aqueous urea;
• a supply pump for pumping aqueous urea from the tank into the exhaust system through a urea injector;
• and
• a heat exchange circuit comprising an inlet and an outlet in communication with the cooling system to provide for the coolant pump to flow liquid coolant through the heat exchange circuit;
• wherein a segment of the heat exchange circuit is disposed in heat exchange relationship with the urea injector, and downstream of that segment there is a controller for controlling the flow of coolant that has exchanged heat with the urea injector to a first branch that is in heat exchange relationship with the tank and the supply pump and a second branch that is not in heat exchange relationship with either the tank or the supply pump.