Olaf Erik Herrmann

Next steps towards EGR-only concept for medium-duty industrial engine

Globally small industrial engines in the range from 2.5 to 4.5 liter displacement play a major role for construction, agricultural and other industrial applications. As shown in Figure 1 the number of emission regulated industrial engines today is still comparable small as especially in Asia and other emerging markets the emission requirements are still limited. Today SCR systems for these small engines just have been introduced and are causing several disadvantages to these applications, like space requirement, need for an infrastructure for a second liquid and additional sensors and actuators which cause some risk to reduce the robustness of these engines and at the same time increase the cost. A significant number of industrial engines in the Asia region will sooner or later require a simple and robust emission reduction technology which is easy to apply to many different applications.

Reduction of Diesel Engine Emissions Performance – Further Steps Towards a Fast and Flexible Fuel Injection

Diesel engines remain the main powertrain concept in view of efficiency and robustness. On the one hand the emissions towards the future EU CO2 limit of 95 g/km by 2021 further demands the reduction of the fuel consumption. On the other hand the new WLTP test cycle and RDE emissions tests demand to reduce the engine-out raw emissions. So far, the main development path of the fuel injection system is focusing on increasing the rail pressure. The increase of the no. of injection events is another approach that aims for phasing the combustion in the working process of the Diesel engine efficiently. This approach is limited by the needle opening speed and capability of closed-coupled injection events. Such features were so far restricted to Piezo injectors. Recently the solenoid injector was enhanced to close this gap and it was firstly tested on an hydraulic test bench and a 4 cyl. passenger car Diesel engine. The hydraulic and engine performance is compared against the solenoid injector G4S and the Piezo injector G4P. With increasing the injection rate steepness and reducing the hydraulic intervals, a triple pilot injection strategy is applied to control the ignition delay and rate of combustion. The steep injection rate reduces the soot emissions without compromising the combustion noise. On the other hand the short interval and fast needle actuation reduces the injection and combustion duration. Thanks to this improved hydraulic performance the BSFC could be improved by 1.7% and soot emissions reduced by 36% at engine part load conditions (2000 rpm, BMEP=6 bar).

Neue Technologien für Abgasnachbehandlung

The post Euro6 and post Tier4, respectively Tier5, emission legislation will not focus on further reduction of the emission limits, but will introduce more stringent test condition and on board diagnostic requirements. Life time stable emissions are already one key requirement for heavy engines and also for passenger car with the coming RDE legislation this will be one of the challenges leading to increased system complexity. On the other hand, the requirements listed in Figure 1 has led to an increased complexity of the diesel powertrain including the after treatment systems. Both passenger car and truck engines are facing the challenge to further reduce CO2 emissions to meet future limits and avoid penalty cost. Thus system complexity reduction must be combined with CO2 reduction.

Further improvement potentials for heavy-duty diesel engines with ultra high injection pressure under transient operation

Die Erfullung der Emissionsgrenzwerte hat in den letzten Jahren die Rahmenbedingungen fur die Auslegung von Nutzfahrzeugmotoren vorgegeben. Neue Motoren wurden entwickelt, die zusatzlich zu den Emissionsanforderungen auch noch hohe spezifische Leistungen moglich gemacht haben. Die thermische Belastung und auch die Spitzendrucke der Motoren sind kontinuierlich gestiegen.