Continental Emitec SCR Dosing System for Passenger Cars and Light Duty Trucks

The Selective Catalytic Reduction (SCR) after-treatment system is already a trend for NOx reduction to achieve diesel emissions regulation.
With increased pressure on CO2 reduction and the phase in of more stringent driving cycles and real driving emissions, it will increase the need for NOx reduction over a wide range of conditions, and tighten the requirements for SCR dosing system.
Dosing accuracy, as well as spray optimization with the exhaust line will stay key requirements to control ammonia buffer in SCR catalyst.
In an effort to minimize heat losses and light off the SCR catalyst sooner automakers have to reposition the SCR catalyst much further upstream and more closely coupled to the engine. This approach has led to an increase in the level and duration of high temperature exposure for the injection device.
Meanwhile for reduction of cold temperature emissions efficient heating strategy of the system is required to achieve dosing readiness time, but also sufficient thawing capacity to maintain SCR efficiency even during the coldest winter conditions.
Short activation time is also required for now standard stop/start application. Precise level measurement is needed to inform the driver who may have to refill between service operations, due to increased AdBlue® consumption. This may lead to refilling errors that the system can detect thanks to a concentration sensor.
This paper review how a complete system approach based on state of the art components, control unit and control functions can achieve such set of requirements.