Long Term Stable NOx Sensor with Integrated In-Connector Control Electronics

Abstract

<div class="htmlview paragraph">This paper describes improvements achieved with regard to the long term stability and the system integrability of a previously described thick film NOx sensor for gasoline lean burn and diesel applications. <sup>(<span class="xref">1</span>, <span class="xref">2</span>, <span class="xref">3</span>)</sup></div> <div class="htmlview paragraph">Durability test up to 1000 hours consisting of a temperature cycle have been carried out by a stoichiometric operating gasoline engine test bench. The NOx sensor demonstrates the NOx output shift in terms of the NOx sensitivity less than 5 % on a model gas apparatus and ± 7 % measuring accuracy in practical operating condition on a diesel engine after 1000 hours that is equivalent to approximately 60K miles driving.</div> <div class="htmlview paragraph">The integration of the control electronics for the sensor in its connector is achieved for the sensitive measuring current in the μA-range or less on vehicle applications. The developed electronics functions closed-loop controls for a tip temperature and oxygen pumps as well as a diagnosis of sensor malfunctions.</div> <div class="htmlview paragraph">It also allows a bi-directional data transmission with the engine management system. The NOx sensor demonstrates a feasibility for a regeneration control and an OBD of a NOx storage catalyst system.</div>