The Dual Mode VCS Conrod System – Functional Development and Oil Investigations



WCX World Congress Experience
Authors Abstract
Variable Compression Systems (VCS) for Internal Combustion Engines (ICE) will become increasingly more important in the future to meet stringent global fuel economy and CO2 standards. A Dual Mode VCS is in development at AVL and the basic functionality and potential were described in a technical paper which was presented at the SAE WCX 2017 [1]. The system is based on a hydraulically switched and locked conrod with telescopic shank.
The AVL Dual Mode VCS was designed and virtually optimized with CAE simulation methods for the boundary conditions of a typical 2.0 L Inline (I) 4 Turbocharged Gasoline Direct Injection (TGDI) engine representing state-of-the-art gasoline engine technology for the next years to come.
Rig tests and motored Single Cylinder Engine (SCE) testing were performed with the Dual Mode VCS hardware to investigate the influence of the oil characteristics on the function, such as different oil grades, different oil temperatures, aged oil, oil aeriation and oil contamination.
Fired SCE and full Multi Cylinder Engine (MCE) tests were performed to validate the general function in the typical operating range of automotive TGDI engines, such as behavior under different mechanical and thermal loads and speeds.
The impact of friction and parasitic losses on the fuel economy were investigated and are discussed in this paper.
This paper also describes and discusses some of the main development results which have been obtained for the Proof of Concept (PoC) and for the completion of the functional and design validation.
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Huettner, T., Millward, P., Loesch, S., and Wolfgang, S., "The Dual Mode VCS Conrod System – Functional Development and Oil Investigations," SAE Technical Paper 2018-01-0878, 2018,
Additional Details
Apr 3, 2018
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Technical Paper