Favourable consumption levels, low CO2 emissions and high torque are the hallmarks of modern diesel engines. Common-rail injection technology and EDC electronic diesel control, both made by Bosch, play a major role in this. These systems for optimising the combustion process in the engine are complemented by Denoxtronic, the Bosch exhaust-gas treatment system. Its current generation cuts nitrogen-oxide emissions by up to 95 percent. Denoxtronic not only cuts emissions, it makes diesel engines more economical as well. Thanks to SCR exhaust-gas treatment, the engine can be configured in such a way that fuel consumption, and thus CO2 emissions, can be lowered by as much as 5 percent.In addition, there are new NOx and particulate sensors that support the diagnosis of exhaust-gas treatment systems, which will become increasingly complex in the future.
xtronic for reducing nitrogen-oxide emissions
In the transition from the Euro 5 to the Euro 6 emissions standard, which is planned for 2014, nitrogen-oxide limits will have to be further reduced by more than half. In particular, powerful diesel engines in heavy passenger cars will require an SCR catalyst (selective catalytic reduction). To meet this requirement, Bosch has adapted its Denoxtronic to the requirements of the passenger car. Denoxtronic has been successfully used in commercial vehicles since 2004. Together with the SCR catalyst, this system transforms any nitrogen oxide in the exhaust gas into harmless steam and nitrogen. It does this by injecting a reagent into the exhaust stream – a urea-water solution known as AdBlue. Electronic diesel control regulates the metering system, ensuring that the amount of AdBlue added is precisely right for engine parameters such as operating temperature and engine speed. In this way, Bosch exhaust-gas technology makes it possible to comply with future emissions standards, such as Euro 6 in Europe or Tier 2 Bin 5 in the United States. Diesel vehicles equipped with Denoxtronic are already available in the European and U.S. markets. By the end of the year, Bosch will have supplied some 500,000 Denoxtronic systems for passenger cars.
NOx and particulate sensors for diagnosis in the exhaust-gas treatment system
In the future, legislation will require that the diesel exhaust-gas treatment system can be diagnosed on board. Vehicles will have to be able to comply with exhaust-gas limits over their entire useful life. For this purpose, Bosch is developing both a particulate and a NOx sensor. Both sensors will be installed in the exhaust-gas flow, along with the wide-band lambda sensor and the differential pressure sensor. The NOx sensor is situated downstream of the SCR catalyst, and measures the amount of NOx in the exhaust gas. Via the CAN bus, it is linked with the engine management system, and at the same time makes sure that the amount of urea injected corresponds with demand. The new particulate sensor is installed downstream of the particulate filter. It is also linked with the engine management system via the CAN bus, and monitors the effectiveness of the particulate filter. Thanks to its comprehensive know-how in exhaust-gas sensors and its electronics competence in the field of engine management, Bosch can offer a future-proof systems solution.