Novel Valvetrain Design as Enabler for Compliance with Upcoming Stringent Emission Demands in Urban Operation

Authors

Dipl.-Ing. N. Andrisani, Dipl.-Ing. F. Contarin, Dipl.-Ing. A. Lorenzon, Eaton s.r.l., Torino;
Dipl.-Ing. M. Nencioni, Dr.-Ing. M. Scassa, Dr.-Ing. F. Mallamo, FEV Italia s.r.l., Torino;
Dipl.-Ing. T. Körfer, Dr.-Ing. H. Busch, FEV Group GmbH, Aachen

Year

2020

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 813

Summary

Lower fuel consumption and reduced emissions are the main drivers for the development of new powertrains for light commercial vehicles. Therefore, technologies like cylinder deactivation, which reduce fuel consumption, improve CO₂ figures as well as thermal management of the exhaust aftertreatment system are highly attractive. In order to allow the usage of cylinder deactivation as soon as possible after engine start, Eaton has developed an innovative electro-mechanical variable valvetrain actuation system capable of cam profile switching down to engine temperatures well below the given minimum Euro 6 test temperature. This consists of a set of Switching Roller Finger Follower (SRFF) being controlled by a single electric actuator via an actuation shaft. The Eaton Electro Mechanical Actuation System (EMAS) is a highly efficient-low energy consuming architecture, easily adaptable to any engine layout, therefore having minimum integration costs. The introduction of a complex technology as cylinder deactivation requires a comprehensive optimization of the operating strategy, especially in conjunction with other engine systems such as boosting and EGR-systems. A virtual development and assessment of these new variabilities is possible with FEV’s mean value-based powertrain simulation process. Based on a typical LCV with a 2.3l-Diesel engine, the operation strategy of cylinder deactivation in combination with a highly flexible airpath was investigated and optimized. Classical cylinder deactivation is limited to a relatively small operation window due to NVH and engine out emission restrictions. Dynamic Skip Fire (DSF), which manages cylinder deactivation on an event-by-event basis, allows extending the operating window with deactivated cylinders considerably and thereby maximizes the improvement of fuel economy and emissions. For full exploitation of the overall potential of VVT/CDA technology, a further increased valvetrain flexibility is required, as individual cylinders need to be activated and deactivated on a cycle-by-cycle basis with fully flexible activation patterns. To meet this requirement EATON is developing e-latch, a further enhanced valvetrain system, having an electro-magnetic actuator on board of each SRFF, enabling individual valve control, extremely low energy consumption, very low and consistent response time: a perfect match for CDA. After comprehensive optimization to exploit the benefit of CDA attractive CO₂ benefits combined with improved thermal management of the exhaust aftertreatment system to minimize pollutant emissions can be realized, exceeding the benefits of conventional cylinder deactivation. These promising results highlight, that advanced valvetrain systems in combination with CDA can comprehensively improve the attributes of Diesel based powertrain and thereby make them fit for the future applications.
The study underlines the cost-effective achievement of fuel consumption savings by an upgrade of the internal combustion engine. In combination with the integration of steel pistons up to 10 g/km CO₂ reduction in the official certification cycle is possible, while meeting the anticipated Post-EU6 emission standards and substantially lowering the risks of oil dilution in real-world driving conditions. A cost advantage of up to 5% versus a 48V equipped engine variant describes a promising option on the base of a modular engine architecture for LCV applications with predominantly long-distance operational profile.