Autonomous auxiliary DEF supply system with purge control

An autonomous auxiliary diesel exhaust fluid (DEF) supply system for supplying DEF to an onboard DEF tank in a diesel engine, comprising:

• an auxiliary DEF tank;
• an auxiliary DEF supply line configured for fluid communication between the auxiliary DEF tank and the onboard DEF tank;
• a pump configured to force DEF through the auxiliary DEF supply line;
• and
• a controller electrically coupled to the pump;
• wherein the controller is configured to command the pump responsive to DEF level signals received from an engine control module of the diesel engine;
• and
• wherein the controller is configured to execute a routine encoded in software for automatically running a purge cycle, wherein the routine executed by the controller comprises:
• running the pump for one fill cycle;
• automatically pausing the system for a predetermined amount of time after completion of the fill cycle, wherein the predetermined amount of time the system is paused is sufficient for DEF delivered to the onboard DEF tank to stabilize in the onboard DEF tank;
• reading an updated stabilized DEF level signal from the engine control module;
• if the updated stabilized DEF level signal indicates that the DEF tank is not full, determining whether the pump has a run a maximum number of fill cycles;
• and
• running a purge cycle if the pump has run the maximum number of fill cycles or if the updated stabilized DEF level signal indicates that the DEF tank is full.

An autonomous auxiliary diesel exhaust fluid (DEF) supply system for supplying DEF to an onboard DEF tank in a diesel engine, comprising:

• an auxiliary DEF tank;
• an auxiliary DEF supply line configured to fluid communication between the auxiliary DEF tank and the onboard DEF tank;
• a pump configured to force DEF through the auxiliary DEF supply line;
• and
• a controller electrically coupled to the pump;
• wherein the controller is configured to command the pump responsive to DEF level signals received from an engine control module of the diesel engine;
• and wherein the controller is configured to execute a first routine and a second routine, each routine encoded in software;
• wherein the first routine executable by the controller comprises:
• running the pump for one fill cycle;
• automatically pausing the system for a predetermined amount of time after completion of the fill cycle, wherein the predetermined amount of time the system is paused is sufficient for DEF delivered to the onboard DEF tank to stabilize;
• reading an updated stabilized DEF level signal from the engine control module;
• if the updated stabilized DEF level signal indicates that the DEF tank is not full, determining whether the pump has a run a maximum number of fill cycles;
• and
• running a purge cycle if the pump has run the maximum number of fill cycles or if the updated stabilized DEF level signal indicates that the DEF tank is full;
• and
• wherein the second routine executable by the controller comprises:
• receiving a low DEF level signal from the engine control module that indicates a low level of DEF in the onboard DEF tank;
• running the pump for a single fill cycle selected to deliver to the onboard DEF tank a volume of DEF that is less than a total volume of the onboard DEF tank;
• receiving an actual DEF level signal from the engine control module that indicates a higher level of DEF in the onboard DEF tank;
• and
• calculating the total volume of the onboard DEF tank based on the low level of DEF, the delivered volume of DEF, and the higher level of DEF.