Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by engines (e.g., IC engines). Conventional exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) catalyst to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3). Generally in such conventional aftertreatment systems, an exhaust reductant, (e.g., a diesel exhaust fluid such as urea) is injected into the aftertreatment system to provide a source of ammonia, and mixed with the exhaust gas to partially reduce the SOx and/or the NOx gases. The reduction byproducts of the exhaust gas are then fluidically communicated to the catalyst included in the SCR aftertreatment system to decompose substantially all of the SOx and/or NOx gases into relatively harmless byproducts which are expelled out of such conventional SCR aftertreatment systems.
The aftertreatment system includes an injector which is configured to inject the exhaust reductant into the aftertreatment system. The injector can include nozzles, valves and/or pumps or other components. The injector is configured to inject a predetermined volume of the exhaust reductant into the aftertreatment system based on operating conditions. In conventional aftertreatment systems, the injector is disposed on an outside surface of the aftertreatment system and is in fluidic communication with the aftertreatment system. In such implementations, the injector is susceptible to damage by objects striking the injector. For example, when the aftertreatment system is included in a vehicle (e.g., a diesel engine operated vehicle), an injector disposed on the exterior of the aftertreatment system included in the vehicle is susceptible to impact from rocks, debris or other objects which can damage the injector leading to malfunction of the aftertreatment system and/or degrade the performance of the aftertreatment system.