aUthors
HOLISTIC CONSIDERATION NECESSARY
DIPL.-ING. MICHAEL NEITZ
i mge Deig f Ceci, Idui d lge Egie FEV Gbh i ace (Gey).
DR.-ING. ANDREAS WIARTALLA
i mge tedyic d afeee f Ceci, Ceci, Idui d lge Egie FEV Gbh i ace (Gey).
DR.-ING. SVEN LAUER i mge siui f Ceci, Idui d lge Egie FEV Gbh i ace (Gey).
The limit values or pollutant emissions o commercial vehicle diesel engines have drastically been reduced during the last two decades. Until today this has been an essential driving orce or the development development o engi ne technologies. Future CO2-limit values are sustaining the pressure or ur ther development. development. The atertreatment o exhaust gases, which to an increasing degree is required or the achievement o legally dened goals, makes a holistic view o the subjects thermodynamics/atertreatment o exhaust gases and base engine design/ mechanics essentially necessary, in order to achieve an optimum with rega rd to product and operating costs. One o the objectives is, or example, to meet t he most avourable point in the trade-o between the complexity o the base engine – among others caused by high peak pressure capability, high injection pressures, elaborate exhaust gas recirculation (EGR) and charge air cooling – and the complexity o the atert reatment o exhaust gases. The systems required today and in uture or atertreatment atert reatment o exhaust gases may cause costs on a sca le approxapproximate to that o the base engine and thus increase the cost pressure on the eng ine. ❶ gives an impression o the range o measures and technologies, which – with an individually dierent degree o maturity each – a re available or han-
dling uture requirements. In this article exemplary issues are examined and possible trends or uture base engine development are discussed, which can help to achieve the above described optimisation. SWEPT VOLUME, DOWNSIZING AND NUMBER OF CYLINDERS
For the reduction o the NOx raw emissions high EGR rates are used today, oten up to ull load engine operation. Due to this the oxygen content in the charge air decreases, which can be compensated by a higher degree o supercharging. Maintaining currently usual top values o the specic power output o clearly more than 30 kW/l kW/l requires dual-stage turbocharging with increased boost pressures under these circumstances, which leads to higher peak pressure requirements on the engine. For an existing engine this way might be the most avourable one. For a complete new development, however, the question arises, i the cost increase caused by exex pensive turbocharging technology and high peak pressure capability, should not be countered with a li mitation o power density, i.e. a correspondingly larger swept volume. Moreover, Moreover, downsizi ng in c onnection with an increased peak pressure does not necessarily promise signicant riction reduction. ❷ shows the comparison o two design variants or a medium-duty truck engine. In this e xample the swept volume is rereduced through a proportional reduction
DR.-ING. FRANZ MAASSEN i Vice Peide f Ceci,
Idui d lge Egie FEV Gbh i ace (Gey).
Demand controlled auxiliaries
Advanced materials
Variable compression ratio Variable valve timing/lift
Thermal spray coating
Combustion refinement
Advanced injection system
Advanced boosting Exhaust gas recirculation
°
Sensors/ controls Waste-heat recovery
SCR technology Advanced catalysts
Particulate filter
❶ Potential technologies or the reduction o emissions and CO 2 10I2012
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G K o C & H b m G s e i g o l o n h c e T r e l f f e a h c S r o f p u d l i u b l a n o s r e p
