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The current legislation for industrial applications and construction equipment including earthmoving machines and crane engines allows different strategies to fulfill the corresponding exhaust emission limits. Liebherr Machines Bulle SA developed their engines to accomplish these limits using SCRonly technology. IAV supported this development, carrying out engine as well as SCR aftertreatment system and vehicle calibration work including the OBD and NOx Control System (NCS) calibration, as well as executing the homologation procedures at the IAV development center. The engines are used in various Liebherr applications certified for EU Stage IIIb, EPA TIER 4i, China GB4 and IMO MARPOL Tier II according to the regulations “97/68/EC”, “40 CFR Part 1039”, “GB17691-2005” and “40 CFR Parts 9, 85, et al.” using the same SCR hardware for all engine power variants of the corresponding I6 and V8 engine families.

Further advancements in engine development lead to increased fuel efficiency and reduced CO₂ emission. Such low emission engine concepts require most advanced exhaust gas aftertreatment systems for lowest possible tailpipe emissions. On the other hand, the exhaust gas purification by catalytic measures experiences more and more challenges due to constantly reduced exhaust gas temperatures by more efficient engines. These challenges can be overcome by traditional catalyst heating strategies, which are known to increase fuel consumption and emissions. Alternatively, electrically heated catalysts ("EHC") can be utilized to provide a very efficient method to increase gas temperatures directly in the exhaust catalyst. This way the energy input can be tailored according to the component need and the energy loss in the system can be minimized.

The clear objective of future powertrain development is strongly characterized by lowest emission impact and minimum overall system cost penalty to the customer. In the past decades emission impact has been primarily related to both optimization of combustion process and exhaust after-treatment system efficiency. Nowadays, weight reduction is one of the main objectives for vehicular applications, considering the related improvements both in fuel consumption (i.e. CO2 production) and engine-out emissions. The state of the art of catalytic converter systems for automotive ZEV-oriented applications has yet to be introduces into mass production. This paper investigates the successful application o metallic turbulent structures for catalytic converters along with innovative packaging considerations, such as structured outer mantle, which lead to significant weight reductions, exhaust backpressure minimization and improved overall emission conversion efficiency.

This paper gives a thorough review of the HC/CO emissions challenge and discusses the effects of different diesel oxidation catalyst designs in a pre turbine and post turbine position on steady state and transient turbo charger performance as well as on HC and CO tailpipe emissions, fuel economy and performance of modern Diesel engines. Results from engine dynamometer testing are presented. Both classical diffusive and advanced premixed Diesel combustion modes are investigated to understand the various effects of possible future engine calibration strategies.

Modern Diesel Engines equipped with Common-Rail Direct Injection and EGR are characterized by an increasingly high combustion efficiency. Consequently the exhaust gas temperature, especially during a cold start, is significantly reduced compared to typical values measured in previous engine generations. This leads to a potential problem with CO emission limit compliance. The present paper deals with an experimental investigation of turbulent-flow metal substrates, carried out on a vehicle roller bench using a production 1.3 Liter diesel engine equipped passenger car. The tested metal supported catalysts proved to yield extremely high conversion rates both during cold start and in warm operation phase. The improved mass transfer efficiency of the advanced metal substrates is related on one hand to the optimized coating technology and, on the other hand, to the enhanced flow performance in the single converter channels which is caused by structured metal foils.

Future stringent emission limits both in the European Community and USA require continuously increased conversion efficiency of exhaust after-treatment systems. Besides the obvious targets of fastest light-off performance, overall conversion efficiency and durability, catalytic converters for maximum output engines require highly optimized flow properties as well, in order to create minimum exhaust backpressure for low fuel consumption. This work deals with the design, development and serial introduction of a close coupled main catalyst system using the innovative technology of Perforated Foils (PE). By means of PE-technology, channel-to-channel gas mixing within the metal substrate could be achieved leading to dramatically reduced backpressure values compared with the conventional design.

Modern Diesel Engines equipped with Common-Rail Direct Injection, EGR and optimized combustion technology have been proven to reduce dramatically engine raw emissions both in terms of Nox and Particulate Matter. As a matter of fact the recently introduced FIAT 1.3 JTD 4 Cylinder Engine achieves Euro 4 limits with aid of conventional 2-way oxidation catalyst. Nevertheless some special applications, such as platforms with relatively higher gross vehicle weight possibly yield to PM-related issues. The present paper deals with the development program carried out to design a cost effective aftertreatment solution in order to address particulate matter tailpipe emissions. The major constraint of this development program was the extremely challenging packaging conditions and the absolute demand to avoid any major impact on the system design. The flow-through metal supported PM Filter Catalyst has been extensively tested on the specific vehicle application with aid of roller bench setup.

This paper gives an overview of the development work for an aftertreatment system, used in hand held powertools to fulfil the corporate average US Limits. The paper will start with a description of the annual reductions in US Limits with differences in CARB and EPA legislation and the consequences of the legislation in Europe from 2007 onwards. There then follows a chapter describing space restrictions in the given muffler leading to a maximum size for the substrate. Tests results are shown, giving an idea of additional measures taken to avoid dangerous temperatures on the muffler surface and of the emitted exhaust gas. The exothermic temperature increase created under service conditions imposes an additional thermal load from the catalyst back towards the engine itself. Therefore, some modifications regarding gas flow and positioning of the catalyst had to be made to find an adequate solution for series production.

The influence of catalyst volume, cell density and precious metal loading on the catalyst efficiency were investigated to design a low cost catalyst system. In a first experiment the specific loading was kept constant for a 500cpsi and a 900cpsi substrate. In a second experiment the palladium loading was reduced on the 900cpsi substrate and the same PM loading was applied to a 1200cpsi substrate with lower volume. Finally the loading was further reduced for the 1200cpsi substrate. The following parameters were studied after aging: Catalyst performance of standard cell density compared to high cell density technology Light-off performance and catalyst efficiency as a function of Palladium loading and substrate cell density Catalyst efficiency as a function of AFR biasing The performance of the aged catalysts was investigated in a lambda sweep test and in light-off tests at an engine bench.

To meet LEV/ULEV - requirements, a considerable amount of development work was necessary to ensure suitable efficiency and durability of catalyst systems [1, 2, 3]. In addition to active emission reduction systems like the Electrically Heated Catalyst (EHC), Exhaust Gas Ignition (EGI) and the burner, passive systems like the HC-trap and Closed-Coupled Catalysts (CCC) are practical solutions to fulfill tighter emission requirements [4, 5, 6, 7]. Depending on the application, thermo-mechanical stresses, vibrations and efficiency degradation through aging increases with the reduction of the distance between the engine and the catalytic converter. Therefore, the test procedures which were suitable for converters which were to be placed in underfloor positions, needed to be modified according to the load spectra acting on close-coupled catalysts. This paper describes a new test strategy used during the development and design verification phase of catalytic converter systems.

From SAE-Papers and several publications, the easy, effective function and management of an EHC-System is well known. The direction of the development is now to reduce the electrical energy consumption and to show the mechanical durability of the heating structure. This paper shows that it is possible to minimize the energy consumption and that the required service life can be in principle achieved with the introduction of these developments. The physical characteristics such as mass, geometrical surface area, cell density and electrical resistance of the EHC construction could be optimized to save energy. This, in conjunction with the operating parameters of the engine, the controlling of the secondary air and the catalyst configuration, will enable the goals to be met. The design of the converter, the physical characteristics and the results of the tests are shown with the Porsche 944 S2 and 968 applications.