Johannes Leweux

Der neue Vierzylinder-Dieselmotor für Pkw von Mercedes-Benz

Mercedes-Benz hat nach langjahriger erfolgreicher Optimierung des bisherigen Vierzylinder-Dieselmotors, dessen Grundabmessungen noch auf dem Vorkammer-Saugmotor OM 601 aus dem Jahr 1983 beruhen, einen komplett neuen Motor mit der internen Bezeichnung OM 651 zur Serienreife entwickelt. Die Potenziale dieses Motors bezuglich Verbrauch, Emissionen und Fahrleistungen wurden durch die konsequente Weiterentwicklung bekannter Techniken sowie den Einsatz wesentlicher neuer motorischer Innovationen erreicht.

Development of a turbocharger compressor with variable geometry for heavy-duty engines

This article describes the first development phase of a centrifugal compressor with variable geometry which is designed to match the needs of future heavy-duty engines. Requirements of truck engines are analyzed, and their impact on the properties of the compressor map is evaluated in order to identify the most suitable kind of variable geometry. Our approach utilizes the transformation of engine data into pressure ratio and mass flow coordinates that can be displayed and interpreted using compressor maps. One-dimensional and three-dimensional computational fluid dynamics fluid flow calculations are used to identify loss mechanisms and constraints of fixed geometry compressors. Linking engine goals and aerodynamic objectives yields specific recommendations on the implementation of the variable geometry compressor.

The Variable Outlet Turbine Concept for Turbochargers

A variable geometry concept for advanced turbocharger (TC) systems is presented. The variability of the device is based on outlet area changes as opposed to the more common systems that are based on inlet turbine geometry changes. In addition to the conventional variable turbine geometry (VTG), the new variable turbine type is termed variable outlet turbine (VOT). The flow variability is achieved by variation of the flow cross section at the turbine outlet using an axial displacement of a sliding sleeve over the exducer and provides a simple solution for flow variability. In order to predict the aerodynamic performance and to analyze the loss mechanisms of this new turbine, the flow field of the VOT is calculated by means of steady state 3D-CFD (computational fluid dynamics) simulations. The VOT design is optimized by finding a good balance between clearance and outlet losses. Furthermore, experimental results of the VOT are presented and compared to a turbine equipped with a waste gate (WG) that demonstrates an efficiency advantage of 5%. Additionally, engine performance measurements were carried out to investigate the influence of the VOT on fuel consumption and to asses the functionality of the new pneumatic actuating system. The VOT engine tests show also performance advantage in comparison to a WG turbine especially toward high engine loads. It is found that the use of the VOT at this condition shows a turbine efficiency advantage of 6% related to a reduction in engine fuel consumption of 1.4%. The behavior at part load is neutral and the peak turbine efficiency of the VOT is comparable with a fix turbine geometry.

In-house developed turbochargers as key technology element for the development of Daimler heavy-duty engines

Reducing the total costs of ownership is a major goal during the development of commercial vehicles. Broken down into objectives with respect to the engine, this is synonymous with a decrease in fuel consumption while meeting the requirements regarding durability and market-specific exhaust-emission legislation. The adjustment of the charging system to the thermodynamic and mechanical boundary conditions of the engine is of great importance to fulfill the development targets.

Experimental Rotordynamic Parameter Study at Turbochargers With Hydrodynamic Journal Bearing Systems

This paper presents an evaluation of various rotordynamic parameters at commercial vehicle turbochargers, which are operated supercritically in full-floating hydrodynamic journal bearing systems. The evaluation is conducted by using an experimental approach to determine the performance of the rotor-bearing-system in a real-life assembly at a hot gas test bench. This takes support stiffness, external heating and the excitation by seals, thrust bearings and gas forces into account, while Engine-specific excitation is not present. The system’s ability to carry additional unbalance load at different oil support pressures without the occurrence of mixed friction throughout a complete run-up is assessed. By executing this assessment for multiple assemblies with different bearings, rotors and oil types, the influence of main design and boundary parameters on the effective journal bearing performance of turbochargers is quantified.Copyright

Variable Asymmetric Turbine for Heavy Duty Truck Engines

Turbochargers with variable turbine geometry (VGT) are established in diesel engines for passenger cars because of the beneficial effect on transient operation. The variability permits the reduction of exhaust back pressure, resulting in lower fuel consumption. There are only a few applications in heavy duty truck engines due to increased mechanical complexity and vulnerability to failure.This paper presents a turbine concept with a simple variability developed for a heavy duty engine. The variability is achieved upstream of the rotor by changing the sectional area of the volute. This can be done through a rotationally movable ring which shifts the circumferential position of the volute tongues. These separate both scrolls of a double segment turbine and can be rotated by an electric actuator.The performance maps measured at the hot gas test stand show the large variability of the flow parameter and the high efficiency levels over the operating range of the variable asymmetric turbine (VAT).The flow field is computed by the use of 3D-CFD simulations in order to analyze the loss-generating mechanisms that occur within the machine.Test runs on an engine test stand demonstrate the high potential of the concept concerning reduction of fuel consumption and a wide scope of realizable EGR rates in order to reduce NOx emissions in a cost-effective way. The resultant large mass flow variability allows the deletion of the waste gate and enables efficiency improvements.© 2013 ASME

The new Mercedes-Benz four-cylinder diesel engine for passenger cars

Following a successful optimisation programme lasting several years for the previous four-cylinder diesel engine whose basic dimensions are still based on the OM 601 prechamber natural aspirated engine of the year 1983, Mercedes-Benz has developed a completely new engine, bearing the internal designation OM 651, to production maturity. The potential of this engine in terms of consumption, emissions and performance was achieved through the systematic advancement of familiar technologies and the use of important new engine-related innovations.