Optimized discrete level sensing system for vehicle reductant reservoir

Abstract

An example emissions-control system of a vehicle includes a reservoir configured to contain a reductant solution, and an SCR device disposed in the exhaust system and configured to consume the reductant solution. The example emissions-control system further includes a base sensor responsive to whether a volume of the reductant solution exceeds a base volume, wherein the base volume is a sum of a dead volume of the reservoir plus a standard volume, and one or more elevated sensors corresponding to one or more elevated volumes. The example emissions-control system further includes an emissions sensor responsive to a NOX level in the exhaust system, and a misformulation indicator operatively coupled to the emissions sensor and to at least one of the base sensor and an elevated sensor, and configured to indicate when an excess NOX emission follows, within an interval, an increase in the volume of the reductant solution above the base volume or an elevated volume. The example emissions-control system may further include an insufficiency indicator operatively coupled to the base volume sensor and configured to indicate when the volume of the reductant solution becomes less than the base volume.

Description

TECHNICAL FIELD[0001]The present application relates to the field of emissions control in vehicles, and more particularly, to control of nitrogen-oxide emissions from diesel-powered vehicles.BACKGROUND AND SUMMARY[0002]An emissions-control system in a vehicle may include a selective catalytic reduction (SCR device) device, wherein nitrogen oxide (NOX) emissions from an engine are combined with ammonia to form dinitrogen and water vapor. Ammonia may be supplied to the exhaust system of the vehicle via a reductant solution, e.g. aqueous urea. Maintenance of the quantity and quality of the reductant solution enables the benefits of the SCR device to be achieved through the operation of the system.[0003]Therefore, U.S. Pat. No. 6,363,771 B1 describes a diagnostic system for a vehicle. The diagnostic system described therein is configured to detect when a level of the reductant solution in a reservoir descends below a threshold, and, based on such detection, to alert the operator of the ...

AI Technical Summary

Benefits of technology

The patent text describes a system and method for controlling emissions in vehicles powered by diesel engines. The system includes a selective catalytic reduction (SCR) device and a reductant solution stored in a reservoir. The system is designed to detect and address issues with the reductant solution, such as misformulation or insufficient reductant level. The technical effect of the patent is to provide a more accurate and reliable diagnosis of emissions-control errors in vehicles, allowing for timely maintenance and repair of the system.

Problems solved by technology

However, the inventors herein have recognized a flaw in this approach.

Specifically, a diagnostic system as described above may not be able to distinguish a misformulated reductant solution from other causes of emissions-control error.

If the diagnostic system determines incorrectly that the reductant solution in a vehicle is misformulated, it may issue erroneous warnings or take inappropriate corrective action—limiting speed or engine power, for example—which may be antagonistic to the operator of the vehicle.

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