Search Results

Due to the constant environmental preoccupation, application of increasingly sophisticated technologies for control of motor vehicle pollutants and necessity of monitoring of such systems, the Embedded Emissions Monitoring System (OBD) was implemented with the primary function of ensuring that the pollutant emissions levels stay within the homologation limits during the whole vehicle useful life. For this reason electronic systems (such as sensors, actuators and model-based functions) are increasingly being used for powertrain control, thereby increasing the complexity of such systems. As a consequence the software fine tuning is also becoming more complex leading to increase of costs during the development phase. In this paper is presented theoretical and practical analysis of the OBD system for Otto (L6) and Diesel (L6 / P7) systems in order to evaluate the differences and identify possible synergies between both applications.

The increasing preoccupation of the environmental impact of automotive vehicles has led to more stringent harmful gases emissions regulations all around the world. In the case of heavy duty diesel vehicles the Brazilian regulations have always been developed according to the existing European ones (Euro), for example the current regulation in Brazil (called Proconve P7 which was introduced in January 2012) follows the same requirements of the Euro V with some minor differences. Europe (remaining the technological leadership position in the automotive segment) has introduced a more stringent emissions regulation called Euro VI in January 2014.

Emission standards are becoming more stringent and at the same time the standards for the On-Board Diagnostic System (OBD) are also continuously enhancing to ensure a more efficient and robust engine emissions monitoring system during the whole vehicle useful life and to improve the quality of the information delivered to the user. In the case of heavy duty diesel vehicles, the Brazilian standards are developed according to the existing European standards (Euro), for example the current standard in Brazil (so called Proconve P7) follows the same requirements of the Euro V with some minor differences. As a consequence, the applied technologies for exhaust gas after-treatment and sensing systems to meet the requirements are already used in European applications such as Selective Catalytic Reduction System (SCR), Exhaust Gas Recirculation (EGR), Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst (DOC), as well as temperature, NOx and differential pressure sensors.

Due to the independent operation between the aftertreatment systems and the engine, the aim of the On Board Diagnostic System (OBD) is to ensure the engine emissions stay within the emissions standards during the whole vehicle useful life. In the case of the heavy duty diesel vehicles that use the Selective Catalytic Reduction System (SCR) or the Exhaust Gas Recirculation System (EGR) as the NOx aftertreatment technologies to meet the stringent emissions levels, the use of sensors in the exhaust pipe is required to control and to monitor the engine emissions. These are new and great challenges to the national diesel engine developers who are working with these systems to get the homologation certification. Accurate mathematic models within the automotive control strategies are becoming ever more important and are strongly used to monitor the NOx emissions directly (in case of SCR systems using the NOx sensor) or indirectly (in case of EGR systems using the Lambda sensor).

Due to the independent operation of the NOx (Nitrogen Oxides) aftertreatment systems from the engine, the aim of the OBD system (OnBoard Diagnosis) is to guarantee the NOx and the Particulate Matter emissions stay within the emissions standards during all the vehicle useful life. In the case of heavy duty diesel vehicles, that use the SCR system (Selective Catalytic Reduction) as the NOx aftertreatment technology, the use of the NOx sensor in the exhaust pipe will be indispensable to control and to monitor the engine emissions. In parallel with these advances in the engine embedded technology for reduction of emissions, it is also advancing the use of biofuels such as biodiesel, which appears as a renewable and clean alternative because it is derived from organic mass and results lower concentrations of some pollutant gases in the exhaust gas in comparison to the fossil fuel.