In-Cylinder Cycle-by-Cycle NOx Measuring Technique in Spark Ignited Engines

Case ID:

Currently, there is no technique that determines the quantity of NOx present at the end of the combustion cycle in spark ignited engines.  Existing technologies for measuring NOx in spark ignited engines are limited to slow response sensors placed in the engine exhaust. 

Wayne State University researchers have developed a novel technique to determine the quantity of NOx that will be emitted with the exhaust gases from each cylinder of spark ignited engines.  The technique utilizes the ion current signal produced from an ion current sensor installed in the combustion chamber to measure NOx on a cycle-by-cycle basis under different steady state and transient engine operating conditions.  Simple and inexpensive ion current sensors, such as a spark plug utilized as an ion current sensor or a fuel injector modified to work as an ion sensor is inserted inside the combustion chamber of each cylinder.  The ion current signal from each cylinder is sent to the engine control unit to adjust different operating parameters for each cylinder to reduce total engine NOx emissions.  


Commercial Applications:

·         Spark ignited engines in the automotive field and other applications

- Direct injection gasoline engines

- Natural gas engines

- Spark ignited HCCI engines

·         Can be incorporated into OEM engine designs or retrofitted to existing engines as an aftermarket product


Technological Advantages:

·         Measuring NOx present in the each cylinder on a cycle-by-cycle basis

·         Ability to adjust engines operating parameters to reduce total engine NOx emissions


Patent Status:

Patent pending

Patent Information:
For Information, Contact:
Nic Wetzler
Wayne State University
Naiem Henein
Fadi Estefanous
Tamer Badawy