Method and system for exhaust heat exchanger diagnostics
First Claim
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1. A method, comprising:
- indicating degradation of a heat exchange system diverting exhaust, via a diverter valve, from downstream of an exhaust catalyst into a heat exchanger in an exhaust bypass, the indicating based on each of 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.
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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.
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Citations
20 Claims
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1. A method, comprising:
indicating degradation of a heat exchange system diverting exhaust, via a diverter valve, from downstream of an exhaust catalyst into a heat exchanger in an exhaust bypass, the indicating based on each of 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method, comprising:
while operating a heat exchange system to flow an entire volume of exhaust from downstream of an exhaust catalyst to a tailpipe 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. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An engine system, comprising:
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an engine intake manifold; an engine exhaust system with an exhaust passage and a bypass passage, the exhaust passage including one or more exhaust catalysts and a muffler, the bypass passage coupled to the exhaust passage from downstream of the one or more exhaust catalysts to upstream of the muffler, the bypass passage including a heat exchanger; a first temperature sensor coupled to the bypass passage upstream of the heat exchanger for estimating a first exhaust temperature; a second temperature sensor coupled to the bypass passage downstream of the heat exchanger for estimating a second exhaust temperature; a pressure sensor coupled to the bypass passage upstream of the heat exchanger for estimating an exhaust pressure; a coolant system with an incoming coolant line and an outgoing coolant line for circulating coolant through the heat exchanger, the coolant system further coupled to each of an engine block and a heater core, the outgoing coolant line including a coolant temperature sensor for estimating a coolant temperature; a diverter valve coupling an outlet of the bypass passage to the exhaust passage; a position sensor coupled to the diverter valve for estimating a diverter valve position; an EGR passage with an EGR valve for recirculating exhaust gas from the bypass passage, downstream of the heat exchanger, to the intake manifold; and a controller with computer readable instructions stored on non-transitory memory for; shifting the diverter valve to a first position and closing the EGR valve to operate the exhaust system in a first mode with exhaust flowing from downstream of the exhaust catalyst to upstream of the muffler via the bypass passage; shifting the diverter valve to a second position and opening the EGR valve to operate the exhaust system in a second mode with exhaust flowing from the bypass passage to the engine intake manifold via the EGR passage; shifting the diverter valve to a second position and closing the EGR valve to operate the exhaust system in a third mode with exhaust flowing directly from downstream of the exhaust catalyst to upstream of the muffler bypassing the heat exchanger; and while operating in one of the first mode and the second mode, indicating degradation of the heat exchanger responsive to each of a difference between the first temperature and the second temperature being higher than a threshold difference, and the second temperature being lower than a threshold temperature; and responsive to the indication of degradation, transitioning to the third mode. - View Dependent Claims (19, 20)
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Specification