Diesels to get cleaner, says Bosch
Component maker reveals techniques for the future
Bosch's HADI injector
Following on the introduction of the Euro 4 emissions standards, the focus of Bosch's development efforts is on the upcoming Euro 5 standards, which will apply from 2010 and are currently being fine-tuned by the EU Commission
Euro 5 represents an enormous challenge for the development engineers in respect of emissions of nitrogen oxides (NOx) and particulates: for particulates, a maximum emission level of a fifth of the current Euro 4 standard is being discussed. That can only be met by using particle filters on all diesel cars.
As well as a diesel particle filter (DPF), Bosch said it is developing a new injection system which will feature extremely precise metering of fuel in order to further reduce the levels of harmful emissions. High injection system pressures and variable control of the injectors through which the fuel is injected into the combustion chambers are both centrally important here.
By using novel piezo-electric technology and maximum injection pressures of 1,600 bar, the third generation of the common rail system introduced by Bosch in 2003 is already capable of meeting the current Euro 4 limits without employing additional exhaust gas after-treatment, said the company. With Euro 5 in mind, Bosch plans to develop and market the system for system pressures of up to 2,000 bar.
Bosch is also developing its fourth generation common rail system with a "Hydraulically Amplified Diesel Injector" (HADI) -- see picture. Using a pressure-amplifying piston, it will enable injection pressures of up to 2,500 bar to be achieved.
"This new technology opens up the possibility of operating with a significantly lower pressure in the Common Rail itself, with the required maximum pressure only being generated in the injector", explained diesel division president Dr. Ulrich Dohle.
Development engineers are also working on improving the unit injector system. The latest UIS3 generation designed by Bosch operates with two actuators instead of one and allows the injection process to be variably configured, with five injections per cycle, similar to the third and fourth generation common rail systems.
In order to exploit the potential of its injection systems to the maximum, Bosch is developing a new engine control unit (EDC17), which will go into series production in 2006. Using revolution counters, the system can analyse the injection parameters of each cylinder and adjust them if necessary. The system permits a simple control system which Bosch said could easily be transferred to a variety of engines and which benefits from the direct feedback from the engine. Precision and resistance to mechanical wear can be optimised.
For breaking down nitrogen oxides in diesel engines, either NOx storage catalytic converters (NSC) or SCR systems are employed. SCR systems require the reducing agent 'AdBlue', which converts the nitrogen oxides into nitrogen and water. Bosch is developing dosage units and control unit designs for these SCR systems. This will allow an especially effective removal of nitrogen oxides with a conversion rate of up to 85 per cent.
Karen Smith said:
I thought the new Euro 4 legislation was for trucks over 7.5 tonnes?
Or am I reading cars into your article when you are talking about engines overall?
No-Euro iv is for cars all right.
Gordon Brown has based company car tax for diesels around it. If they are not Euro iv compliant they get moved up 3%.
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