| US 7,588,368 B2 | ||
| System for diagnosing temperature sensor operation in an exhaust gas aftertreatment system | ||
| Eric L. Hagen, Trafalgar, Ind. (US); and Jaideep Prasad, Columbus, Ind. (US) | ||
| Assigned to Cummins Inc., Columbus, Ind. (US) | ||
| Filed on Dec. 20, 2006, as Appl. No. 11/613,770. | ||
| Prior Publication US 2008/0151964 A1, Jun. 26, 2008 | ||
| Int. Cl. G01K 15/00 (2006.01); G01K 17/00 (2006.01); G01K 3/08 (2006.01) | ||
| U.S. Cl. 374—40 [374/29; 374/135; 374/137; 374/152] | 15 Claims |
| 1. A method for diagnosing operation of three temperature sensors each disposed at a different location along a single exhaust
flow path fluidly connected to an exhaust manifold of an internal combustion engine, the method comprising:
receiving a first temperature signal from a first of the three temperature sensors,
receiving a second temperature signal from a second of the three temperature sensors,
receiving a third temperature signal from a third of the three temperature sensors,
determining an exhaust gas flow rate corresponding to a flow rate of exhaust gas flowing through the single exhaust flow path,
determining a first average temperature differential between the first and second temperature sensors as a function of the
first temperature signal, the second temperature signal and the exhaust gas flow rate,
determining a second average temperature differential between the first and third temperature sensors as a function of the
first temperature signal, the third temperature signal and the exhaust gas flow rate, and
producing a first fault signal if a difference between the first and second average temperature differentials exceed a threshold
value.
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