Model based diagnostics of an aftertreatment fuel dosing system
View Patent ↗The invention relates to systems and methods of detecting faults in an exhaust line fuel injection system. An expected relationship between a temperature within the exhaust system and a commanded fuel injection rate or amount is compared to an actual relationship in order to detect faults. The temperature is preferably a temperature of, within, or downstream of an exhaust system device that catalyzes an oxidation or partial oxidation reaction of the fuel, such as an oxidation catalyst or a fuel reformer. The expected relationship may be defined in terms of a thermal model of a system comprising the catalytic device. The invention can be used to detect spray quality faults or to detect fuel injector faults without the use of flow meter.
1. A fault detection method, comprising:
injecting fuel into an exhaust line using a fuel injection system comprising a fuel injector whereby the fuel mixes with exhaust;
passing the fuel-exhaust mixture through a device that catalyzes oxidation or partial oxidation reactions of the fuel;
detecting a temperature of the device, within the device, or downstream of the device; and
using the detected temperature in detecting a fault in the fuel injection system;
wherein using the detected temperature in detecting a fault in the fuel injection system comprises the application of a thermal model of a system comprising the device
wherein the thermal model comprises a term relating to heat of reactions of the fuel, a term relating to heat capacity of the device, and a term relating to convective heat transfer by the exhaust.
2. A method of diagnosing a fuel injection system, comprising:
supplying fuel to a fuel reformer through the fuel injection system;
measuring a temperature of the reformer or a reformer exhaust stream;
analyzing data comprising the temperature measurement to determine whether the fuel injection system has experienced a fault; and
if a fault is detected, recording the fault in a memory or signaling the fault
wherein analyzing data comprising the temperature measurement to determine whether the fuel injection system has experienced a fault comprises application of a thermal model of a system comprising the device;
wherein the thermal model comprises a term relating to heat released by reactions of the fuel, a term relating to heat capacity of the device, and a term relating to convective heat transfer by the exhaust.
3. A method of diagnosing a fuel injection system, comprising:
supplying fuel to a fuel reformer through the fuel injection system; and
comparing an expected relationship between a commanded fuel injection rate and a temperature to an actual relationship between the commanded fuel injection rate and the temperature and thereby checking for a fuel injection fault;
wherein the expected relationship is a model-based relationship;
wherein the model comprises a term relating to heat released or taken up by reactions of the fuel, a term relating to heat capacity of the fuel reformer, and a term relating to convective heat transfer by the exhaust.