Schaeffler Group Developing New Electric Cam Phasing System
10 April 2007
The Schaeffler Group, a global automotive supplier of rolling bearings and linear products, is developing a new ultra-fast electrically operated cam phasing system that allows rapid adjustment of cam timing for all engine speeds and engine temperatures.
Variable cam phasing is a mechanism to support variable valve timing. Depending upon the implementation, it can be used to shift the intake cam, the exhaust cam, or both on dual overhead cam engines. This helps increase engine efficiency and stability at idle while delivering more torque and horsepower. It also helps to reduce fuel consumption and emissions.
Production cam phasing systems have been mechanical or hydraulic. Two recent exceptions are Lexus’ new VVT-iE system, debuting on the Lexus 600h L hybrid, which uses an electric motor-driven intake camshaft (earlier post) and Nissan’s new VVEL, debuting on the Infiniti G37 (earlier post).
The Schaeffler system, which is being presented in a technical papers during the 2007 Society of Automotive Engineers (SAE) World Congress held in Detroit from April 16 to 19, allows an aggressive calibration of the cam timing, hence improving fuel economy and engine response.
The system can even be used during engine start-up, hot idle or at sub-zero temperatures. It can ideally be combined with novel combustion concepts, such as direct injection (DI) or homogeneous charge compression ignition (HCCI), according to the company.
Additional fuel economy benefits can be gained by adapting the engine oil system to the reduced requirements. The Schaeffler Group will discuss its solution to electrical camshaft phasing in this presentation and show test results that demonstrate the system’s abilities.
A second Schaeffler paper, presented jointly with representatives from GM, will discuss the new Active Fuel Management system (cylinder deactivation) and the adaptation of AFM to the 2007 3.9-liter V-6 engine. This approach to cylinder deactivation can lead to fuel economy improvements of up to 5 to 7%.
A third paper, not presented, but available, will discuss vibration control solutions based on the increase of torsional energy in the front end accessory drive, which results from deactivating cylinders in an engine.
Schaeffler Group members are Schaeffler KG with its two brands, INA and FAG, headquartered in Herzogenaurach, Germany and the LuK Group which is based in Bühl/Baden, Germany. The Automotive Division is a partner to nearly all major automotive manufacturers and suppliers, providing system solutions for the entire vehicle, including engine, transmission and chassis.
“High Performance Electric Camshaft Phasing System”; Jens Schaefer and Jeff Balko
“Active Fuel Management (AFM) Technology: Hardware Development on a 2007 GM 3.9L V-6 OHV SI Engine”; David Kehr, James Westbrook III, Henning Karbstein, and Mario Kuhl from the Schaeffler Group, INA; and Mark Stabinsk, William Albertson, and Jim Tuttle from GM.
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