Control strategy for diesel engine auxiliary loads to reduce emissions during engine power level changes

A method for controlling the activation of auxiliary loads of an internal combustion engine of a locomotive, wherein the engine is drivingly coupled to a main alternator and an auxiliary alternator, wherein the main alternator provides current to one or more traction motors for providing motive power to the locomotive, and wherein the auxiliary alternator provides current to a plurality of auxiliary loads operative in conjunction with an associated subsystem, and wherein the locomotive further includes a manually-operated controller having a plurality of notch positions, and wherein each notch position commands an engine speed/horsepower pair, said method comprising:

• determining whether a higher notch position has been commanded by movement of the manually-operated controller;
• determining whether the internal combustion engine has reached the engine speed/horsepower of the higher notch position;
• determining whether a command has issued to control one of the plurality of auxiliary loads because the operational parameter of the associated subsystem has a predetermined relation to a first predetermined limit;
• determining whether the operational parameter of the associated subsystem has a predetermined relation to a second predetermined limit;
• if the operational parameter has the predetermined relation to the second predetermined limit, controlling the auxiliary load;
• and
• if the operational parameter has the predetermined relation to the first predetermined limit and does not have the predetermined relation to the second predetermined limit and the internal combustion engine has not reached the engine speed/horsepower of the higher notch position, waiting until the internal combustion engine reaches the engine speed/horsepower of the higher notch position, after which the command is executed to control the one of the plurality of auxiliary loads.

A control system for an internal combustion engine comprising a plurality of subsystems, a traction load and a plurality of auxiliary loads, wherein the internal combustion engine supplies operating energy to the traction load and to the plurality of auxiliary loads, and wherein the internal combustion engine operates in a transient mode while the engine speed or horsepower is transitioning to a commanded value in response to an operator-initiated request, or operates in a steady-state mode during which the engine speed and horsepower are substantially stable at the commanded value, said control system for controlling the plurality of auxiliary loads, comprising:

• a first module for determining when a request for an engine speed or horsepower change to a commanded value has been initiated and for determining engine operational parameters;
• a second module for determining the relationship between an operational parameter for at least one of the plurality of subsystems and a first and a second predetermined threshold value, and for activating the auxiliary load associated with the one of the plurality of subsystems when the operational parameter of the subsystem has a predetermined relation with the first threshold value and the engine is in a steady-state mode, wherein in the steady-state mode the engine speed and horsepower are substantially stable at the commanded value;
• and
• wherein said second module activates the auxiliary load associated with the one of the plurality of subsystems when the operational parameter of the subsystem has a predetermined relation with the second threshold value and the engine is in a transient mode, wherein in the transient mode the engine speed or horsepower is transitioning to the commanded value.