While steel pistons have been in use for a long time in commercial vehicle diesel engines, the first series production applications for passenger car diesel engines are currently imminent. The main reason for the use of steel pistons in high speed diesel engines is not, as maybe initially hypothesized, the increasing requirements on the component strength due to increasing mechanical loads, but rather challenges based on the actual C 02legislation. The increasing requirements to reduce the fuel consumption necessitate new innovative technologies. The imminent penalties for exceeding the prescribed C 02 emis sions seem to make the steel piston a viable alternative today, despite its higher manufac turing costs. So far, the C02-benefits using steel pistons were mainly ascribed to the reduced friction between piston and cylinder liner due to no thermal interference. Journal of Engineering for Gas Turbines and PowerOCTOBER 2 0 1 4 , Vol. 136 / 1 0 1 5 0 6-7

With the increase of combustion loading and the trend to reduce engine size, there is a need for thinner but stronger wet cylinder liners. While most of the current cylinder liners are made of gray cast iron, due to its good tribological behavior, machinability performance and competitive price, alternative casting materials like compact graphite iron, ductile iron and even steel are being considered to cover the future engine demands. In this paper, a new ductile iron (DI) cast material for wet cylinder liners is presented. The material has about 60 and 70% higher limits respectively for tensile stress and fatigue resistance as compared to conventional gray cast irons, but without penalty on the tribological properties. There is also a potential improvement to avoid cavitation on the outside surface due to its higher young modulus, which also equates to a higher stiffness. The tested cylinder liners were induction hardened on the running surface and a slide hone process was used to improve wear and scuffing resistance. The liners were tested in a HDD engine with PCP of 245 bar and showed similar wear as observed with conventional cylinder liners of gray cast iron material. The DI cylinder liners were also tested in an abusive scuffing engine test without any concern. The improved mechanical properties of the described new DI material introduce possibilities to reduce liner wall thickness or increase specific output. The preliminary evaluation in this paper showed that this new material is feasible for HDD diesel engines with PCP up to 250 bar. In cases that the customer needs to increase the bore diameter for output reasons there is the potential to reduce the liner wall thickness up to 25% based on high mechanical properties (UTS, Young Modulus and fatigue strength). In both cases, it’s recommended a FEA analysis to support the new component design.

With the increase of combustion loading and the trend to reduce engine size, there is a need for thinner but stronger wet cylinder liners. While most of the current cylinder liners are made of gray cast iron, due to its good tribological behavior, machinability performance, and competitive price, alternative casting materials such as compact graphite iron, ductile iron, and even steel are being considered to address future engine demands. In this paper, a new ductile iron (DI) cast material for wet cylinder liners is presented. The material has about 60 and 70% higher limits, respectively, for tensile stress and fatigue resistance as compared to conventional gray cast irons, but without a penalty on the tribological properties. There is also a potential improvement to avoid cavitation on the outside surface due to its higher young modulus, which also equates to a higher stiffness. The tested cylinder liners were induction hardened on the running surface and a slide hone process was used to improve wear and scuffing resistance. The liners were tested in a heavy duty diesel (HDD) engine with a peak cylinder pressure (PCP) of 245 bar and showed similar wear as observed with conventional cylinder liners of gray cast iron material. The DI cylinder liners were also tested in an abusive scuffing engine test without any concern. The improved mechanical properties of the described new DI material introduce possibilities to reduce the liner wall thickness or increase specific output. The preliminary evaluation in this paper showed that this new material is feasible for HDD diesel engines with a PCP up to 250 bar. In cases where the customer needs to increase the bore diameter for output reasons there is the potential to reduce the liner wall thickness by up to 25% based on high mechanical properties (UTS, Young’s modulus and fatigue strength). In both cases, a FEA analysis to support the new component design is recommended.

While steel pistons have been in use for a long time in commercial vehicle diesel engines, the first series production applications for passenger car diesel engines are currently imminent. The main reason for the use of steel pistons in high speed diesel engines is not, as maybe initially hypothesized, the increasing requirements on the component strength due to increasing mechanical loads, but rather challenges based on the actual CO2-legislation. The increasing requirements to reduce the fuel consumption necessitate new innovative technologies. The imminent penalties for exceeding the prescribed CO2 emissions seem to make the steel piston a viable alternative today, despite its higher manufacturing costs. So far, the CO2-benefits using steel pistons were mainly ascribed to the reduced friction between piston and cylinder liner due to no thermal interference. Fuel consumption measurements at vehicle manufacturer and research institutes hypothesize also an influence of the steel piston on the thermodynamic efficiency. MAHLE uses engine tests to investigate one piston variant made of aluminum (series production piston with cooled ring carrier) and one of steel (MAHLE TopWeld) in a detailed system comparison. Using a fully indicated engine, a combustion process analysis is performed and used as the basis for a loss analysis. The engine set-up parameters can be adjusted fully variable using a flexible ECU. The effect that the piston variant has on the combustion process is captured and balanced, e.g., by adjusting the parameters to obtain identical emissions. The analysis records the potential of the variants for each engine operating map area. The thermal conditions for the piston and the piston wall temperature on the combustion chamber side are varied over a wide range using a conditioning device for piston cooling. The influence of this intervention on the thermal load of the piston and the combustion and also the influence of different combustion mappings is measured directly by telemetric piston temperature measurement. MAHLE recently completed a system comparison [3] between aluminum and steel pistons with detailed measurements on a fully indicated engine, covering friction and temperature behavior as well as influences on combustion.

This paper analyzes alternatives to carbon-based fuels, including ‘clean’ electric locomotive technology. Electrification of the North American railway network leaves many questions to be researched, such as: sufficient power capacity, ‘clean’ sources, distribution costs, infrastructure costs, logistics issues, legislative barriers, and resulting changes to business practises. A comprehensive review of incentives, logistics, and barriers was done to shed some light on emerging research needs to fill knowledge gaps in time to sustain industry competitiveness, and to meet the demands of a more sustainable future for North American freight, commuter, and tourism rail. Given prohibitively high costs and logistics of rail electrification, North American researchers have started focusing on ultra-capacitors and batteries. Previous research suggests that a hybrid capacitor/battery equipped locomotive would work, all within the existing envelope of locomotive chassis, and with much lower infrastructure costs. The transition in NA would be faster, at a much lower cost, including high speed passenger rail. However, no one has yet done the necessary research to verify this hypothesis.