Eaton has announced that it is ‘the first tier one supplier in the automotive industry to develop a production-ready electromechanically actuated, component-based VVA (variable valve actuation) system’.
The system is claimed to have several advantages over existing hydraulically actuated variable valve actuation systems, including reduced fuel consumption and increased engine efficiency, and is ideally suited to address future emission standards. Several OEM partners are currently evaluating the design in next generation engine tests.
The electromechanical actuation system can be used with all SRFF (switching roller finger follower)-based VVA solutions to enable functions such as cylinder deactivation, Miller cycle, internal exhaust gas recirculation (iEGR) or early exhaust valve opening. The actuation system has already undergone extensive rig and fired testing on a diesel engine providing internal exhaust gas recirculation (iEGR) functionality. The immediate benefit from using this new electromechanical actuation system versus a conventional hydraulic system is consistently fast response time regardless of the engine temperature or speed.
A growing proportion of vehicle manufacturers are looking to VVA as a means of meeting fuel consumption, engine efficiency and emission targets without compromising the engine’s performance capabilities. However, current series production component-based VVA systems rely on electrohydraulic actuation of switchable roller finger followers (SRFFs), and this technology has a number of limitations.
The reliance on hydraulic oil – which is susceptible to variances in temperature and pressure – impacts the speed, predictability and consistent repeatability of VVA activation and deactivation through the driving cycle. In addition, hydraulic systems require higher oil-flows which contribute to parasitic energy losses.
Different predefined groups of rocker arms can be actuated electrically to each act on either intake or exhaust valves. This allow for various combinations of valve-lift profiles to be utilized by combustion engineers to minimize emissions without compromising performance. Switching to a new VVA profile by the ECU can be completed in less than 35 milliseconds at less than -7°C.
In addition to faster actuation, the new electromechanical system has a far greater degree of consistency and predictability and is available at an engine-off condition even before cranking.
With greater confidence of the system’s speed, repeatability and consistency, engineers can design the combustion strategy more precisely. This is crucial for vehicle manufacturers that need to maximise engine efficiency through the entire drive cycle in order to meet increasingly stringent emissions standards. The system provides unique advantages in reducing emissions at cold temperatures where an after treatment system does not work.
With the design of the electromechanical actuation system being production ready today, Eaton is already developing the next generation actuation system. The next system will give customers full control over every individual SRFF while significantly reducing packaging requirements compared to current hydraulic actuation systems.
“Eaton has a long history of leadership in valvetrain developments and this is the next major step forward,” said Carlo Ghirardo, president Vehicle Group EMEA at Eaton. :This latest technology supports our customers by meeting future consumer and legislative demands for increased efficiency and lower emissions. We look forward to delivering this technology for the next generation of automobiles.”
