Scr emissions-control system
AssigneeFord Global Technologies, LLC
InventorJoseph Robert Theis
Life of this patent
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Abstract
An emissions-control system of a vehicle is provided, having an LNT disposed in an exhaust system of the vehicle, downstream of the engine, an SCR device disposed downstream of the LNT, and a controller. The controller is operatively coupled to the engine and configured to cause the engine to provide a reducing exhaust to the LNT at least during an enrichment interval, the enrichment interval including an enrichment subinterval beginning after a sensor indicates rich breakthrough, and further configured to adjust the duration and/or the level of enrichment for the enrichment subinterval in response to an ageing of the LNT. In this way, it is possible to modify LNT regeneration based on catalyst performance and thereby generate sufficient ammonia for improved operation of the SCR device.
Claims20
An emissions-control system of a vehicle coupled to an engine of the vehicle and comprising:
- an LNT disposed in an exhaust system of the vehicle, downstream of the engine;
- an SCR device disposed in the exhaust system of the vehicle, downstream of the LNT;
- and
- a controller operatively coupled to the engine, configured to cause the engine to provide a reducing exhaust to the LNT during an enrichment interval, the enrichment interval including an enrichment subinterval, the controller further configured to adjust the enrichment subinterval in response to an ageing of the LNT.
An emissions-control system of a vehicle coupled to an engine of the vehicle and comprising:
- an LNT disposed in an exhaust system of the vehicle, downstream of the engine;
- an SCR device disposed in the exhaust system of the vehicle, downstream of the LNT;
- a sensor disposed in the exhaust system of the vehicle, upstream of the SCR device, and configured to report when an exhaust-stream air-fuel ratio traverses a threshold;
- and
- a controller operatively coupled to the engine, configured to cause the engine to:
- provide a lean exhaust to the LNT, transition to providing a richer exhaust to the LNT, and continue providing the richer exhaust to the LNT during an enrichment interval, the enrichment interval including an enrichment subinterval starting when the sensor reports that the exhaust-stream air-fuel ratio has traversed the threshold;
- and further configured to adjust a duration of the enrichment subinterval in response to an ageing of the LNT.
A method to provide ammonia to an SCR device disposed downstream of an LNT in an exhaust system of a vehicle, the method comprising:
- enriching an exhaust flow to the LNT during an enrichment interval, the enrichment interval including an enrichment subinterval, wherein the enrichment subinterval is lengthened as the LNT becomes further aged;
- and
- disabling enrichment of the exhaust flow at an end of the enrichment subinterval.
Dependencies are inferred from the claim text.