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Amorphous Carbon Coatings for Low Friction and Wear in Bucket Tappet Valvetrains
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Abstract
Fuel economy is a major driver in the development of new passenger car engines. One requirement for a good fuel economy is to achieve a low level of mechanical friction. The valvetrain can contribute a substantial part to this mechanical friction, especially at low speeds where fuel economy is most important.
As a result of this, friction optimized engines often have a roller follower type valvetrain design despite its disadvantages versus bucket tappet concepts in other aspects.
This paper presents a study on modern amorphous carbon coatings at the cam / tappet interface aimed to investigate the potential for bucket tappet valvetrains to overcome the friction disadvantage. The work presented is divided into
- 1)a pin-on-disk pre-study to identify coatings with the most promising properties and
- 2)a cylinder head friction study to validate the findings in the realistic environment.
The paper demonstrates that the coatings have a substantial potential for friction and wear reduction. However, a universal recipe how to successfully apply a coating can not be given since the optimum coating strongly depends on the right balance of properties for each application. Surface hardness, coefficient of friction, oil wettability and surface topography all have to be matched to the application.
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Citation
Schamel, A., Grischke, M., and Bethke, R., "Amorphous Carbon Coatings for Low Friction and Wear in Bucket Tappet Valvetrains," SAE Technical Paper 970004, 1997, https://doi.org/10.4271/970004.Also In
References
- Heywood, J. Internal Combustion Engine Fundamentals Mc Graw-Hill New York
- Phlips, P Schamel A. An efficient Model for Valvetrain and Spring Dynamics Transactions SAE 1989
- Phlips, P Schamel A. The Dynamics of Valvetrains with Hydraulic Lash Adjusters and the Interaction with the Gas Exchange Process SAE Paper 910071
- Schamel, A Hammacher J. Utsch D. Modelling and Measurement Techniques for Valve Spring Dynamics in High Revving Internal Combustion Engines Transactions SAE 1993
- Ernst, R Schamel A. Advanced Optimization Techniques in Valvetrain Design Transactions SAE 1993
- Kaiser, H-J Phlips Schamel A. Engine Noise Reduction by Camshaft Modifications in Multi-Valve Engines 2nd Aachen Colloquium Engine Technology
- Grischke M. Bewilogua K. Dimigen H. Materials & Manufacturing Processes 8 4&5 1993 407 417
- Klages C.P. Memming R. Materials Science Forum 52 53 1989 609 644
- Enke K. Dimigen H. Hübsch H. Appl- Phys. Lett. 36 1980 291
- Bewilogua K. Dimigen H. Surf. Coating. Technol. 61 1993 144
- Grischke M. Bewilogua K. Trojan K. Dimigen H. Surf. and Coat. Techn. 74-75 1995 739 745
- Meißner, Polzer VEB-Verlag Leipzig 1978 87
- Grischke M. Trojan K. Dimigen H. Proc. Joint 4th Int. Symp. on Trends and New Applications in Thin Films 11th Conf. on High Vacuum, interfaces and Thin Films 1994 433
- Trojan K. Grischke M. Dimigen H. Phys. Stat. Sol. 145 1994 575