System and method for post-shutdown temperature management and purge

A method for thermal management and post-shutdown purge of a fluid from an injector in a machine having an engine, the engine having a coolant system and an electrical system associated therewith, the engine electrical system including a power storage device, the method comprising:

• storing electrical energy in an auxiliary power unit that includes a battery array from the electrical system during engine operation, the auxiliary power unit being separate from the power storage device of the engine electrical system;
• activating the auxiliary power unit to deliver electrical power after engine shut-down and deactivation of the engine electrical system that includes the power storage device;
• powering a fluid pump to purge the fluid from the injector using electrical power from the auxiliary power unit;
• sensing a temperature of the injector and, based on the temperature, activating a coolant pump that is separate from the coolant system of the engine, the coolant pump operating in a secondary cooling system to reduce an injector temperature when the sensed temperature is or is expected to exceed a threshold temperature after the engine and the engine electrical system are shut down;
• wherein the coolant pump of the secondary cooling system draws electrical power for operation from the auxiliary power unit, and
• wherein a flow of electrical power to the fluid pump and to the coolant pump of the secondary cooling system is controlled by a power management module that is associated with the auxiliary power unit, the fluid pump, and the secondary cooling system.

A method for avoiding overheating of a diesel exhaust fluid (DEF) injector disposed in an engine exhaust system following a hot engine shut-down, comprising:

• activating an auxiliary power unit, which includes a battery array that is separate from a power storage device of the engine and operates to store electrical energy therein during engine operation and to selectively deliver, upon activation, electrical power after engine shut-down and deactivation of an engine electrical system;
• sensing a temperature associated with the DEF injector and, when and while the temperature exceeds a predetermined threshold:
• using energy from the auxiliary power unit to operate a fan providing a cooling air flow to the DEF injector;
• using energy from the auxiliary power unit to operate a coolant pump that circulates a flow of coolant fluid through a passage formed in a housing of the DEF injector;
• wherein a flow of electrical power to the fan and to the coolant pump is controlled by a power management module that includes a controller associated with the auxiliary power unit.