System and Method for Injector Fault Remediation

Abstract

A machine includes an engine having an exhaust system. A diesel exhaust fluid (DEF) injector provides metered amounts of DEF and includes a valve adapted to selectively open in response to a command. A controller associated with the engine and the DEF injector monitors operation of the DEF injector to detect a fault and activates a failure remediation cycle when the fault has been detected. The remediation cycle includes heating the exhaust gas to heat the DEF injector and melt any urea crystals that may be causing the fault, and activating the valve of the DEF injector to evacuate molten urea from within the DEF injector.

Description

technical field [0001] The present invention relates generally to engine systems, and more particularly to exhaust aftertreatment systems and methods. Background technique [0002] One known method for removing certain diesel engine exhaust constituents is the use of exhaust aftertreatment systems utilizing selective catalytic reduction (SCR) of nitrogen oxides. In a typical SCR system, urea or a urea-based aqueous solution is mixed with the exhaust gas. In some applications, the urea solution is injected directly into the exhaust passage via a dedicated injector device. The injected urea solution mixes with the exhaust gas and decomposes to provide ammonia (NH 3 ). Ammonia then reacts at the catalyst with nitrogen oxides (NO X ) reaction to provide nitrogen (N 2 ) and water (H 2 O). [0003] As can be appreciated, SCR systems require some form of urea to be present near the engine system so that the engine can be continuously supplied with urea during operation. Var...

AI Technical Summary

Problems solved by technology

In known urea injection systems, challenges related to temperature and / or pressure can arise which affect the electrical and mechanical hardware used to inject urea

Considering, for example, that urea is usually injected directly into an engine's exhaust system in the form of an aqueous solution, changes in solution concentration due to thermal or pressure effects can hamper the injector during system operation and after thermal saturation following a hot engine shutdown normal work

Also, for systems using water-based urea solutions, depressurization and / or boiling of the system can cause urea to crystallize at the injector, which can clog the injector

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