Method and system for exhaust heat exchanger diagnostics
AssigneeFord Global Technologies, LLC
InventorsKaren Evelyn Bevan, Ross Dykstra Pursifull, Michael James Uhrich, Joseph Norman Ulrey
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Abstract
Methods and systems are provided for carrying out on-board diagnostics of a plurality of components of an exhaust heat exchange system. In one example, degradation of one or more of a heat exchanger and a coolant system fluidically coupled to the heat exchanger may be detected based on a first temperature estimated upstream of the heat exchanger, a second temperature sensor estimated downstream of the heat exchanger, a coolant temperature, and a pressure estimated upstream of the heat exchanger. Also, degradation of a diverter valve of the heat exchange system may be detected based on inputs of a position sensor coupled to the diverter valve.
Claims20
A method, comprising:
- diverting engine exhaust for a turbo-charged direct injection engine, via a diverter valve of a heat exchange system, from downstream of an exhaust catalyst and downstream of a turbocharger turbine into a heat exchanger in an exhaust bypass;
- and
- indicating degradation of the heat exchange system based a first exhaust temperature and an exhaust pressure estimated upstream of the heat exchanger, a second exhaust temperature estimated downstream of the heat exchanger, and a temperature of coolant circulating through the heat exchanger sensed by a temperature sensor, the coolant returned to the engine or a heater core from the heat exchanger.
A method, comprising:
- generating exhaust gas form a direct injection turbocharged engine;
- while operating a heat exchange system to flow an entire volume of the exhaust from downstream of an exhaust catalyst to atmosphere via an exhaust bypass housing a heat exchanger,
- indicating degradation of the heat exchanger responsive to each of an exhaust pressure measured upstream of the heat exchanger being higher than a first threshold pressure, and a temperature difference between a first exhaust temperature measured upstream of the heat exchanger and a second exhaust temperature measured downstream of the heat exchanger being higher than a first threshold difference;
- indicating degradation of a coolant system circulating coolant through the heat exchanger responsive to coolant temperature measured at an outgoing line of the coolant system being lower than a first threshold coolant temperature;
- and
- indicating a diverter valve coupled at a junction of the exhaust bypass and a main exhaust passage is stuck closed or partially open responsive to an actual position of the diverter valve differing from a fully open position.
Dependencies are inferred from the claim text.