Modal Analysis Of Valve Train Test Rig Support Structure

Improvement of fuel economy is one of the most important development targets of modern passenger car engines. Modern solutions such as Direct Injection, Variable Valve Trains, or Cylinder Deactivation help to obtain this requirement. Each one of these techniques optimize the thermodynamic efficiency of the engine. However, the mechanical structure of combustion engines shows many areas of possible optimization regarding the mechanical efficiency. Engine friction affects the overall fuel consumption, mainly under low speed conditions combined with part load. Low speed/part load conditions are relevant for the real life fuel consumption of an engine, as well as friction improvements have significant effects on the fuel economy. The valve train drive produces the dominant friction portion under these conditions. Hence the friction optimization of this engine subsystem is one of the key issues regarding mechanical efficiency. The valve train friction consists mainly of friction produced by the contact between cam and cam follower, e.g. tappet or finger lever. The introduction of a roller contact to the cam, is a known optimization method. However the cam shaft bearings need to be optimized as well. This paper explains the influence of the cylinder head structure on the behavior of the cam shaft bearings. The modal analysis method shows the test rig structure influence on the valve train components during vibrational analysis. Conclusions and suggestions for the system are presented. Copyright © 2001 Society of Automotive Engineers, Inc.Dedini, F.G., Cavalca, K.L., Aplicação de métodos de identificação teórico experimentais na análise de um turbogerador com sete mancais (1993) XII COBEM CONGRESSO BRASILEIRO de ENGENHARIA MECÂNICA, pp. 1241-1244. , Brasília - Brasil, DezembroCavalca, K.L., Cavalcante, P.F., Interação rotor-estrutura de fundação através de mancais hidrodinâmicos (1997) XIV COBEM CONGRESSO BRASILEIRO de ENGENHARIA MECÂNICA, , Bauru - Brasil, DezembroCavalcante, P.F., Cavalca, K.L., A method to analyse the interaction between rotor-foundation systems (1998) IMAC 98 International Modal Analysis Conference, , Santa Barbara - USA, FevereiroJainski, T., Modal resolution of transient vibrations in Rotor-Bearing-foundation systems caused by electrical system faults (1982) IFToMM - INTERNATIONAL CONFERENCE, pp. 177-189. , Rome -Italy, September 1982Weiming, L., Novak, M., Dynamic behavior of turbine-generator- foundation systems (1996) Earthquake Engineering & Structural Dynamics, 24 (3), pp. 339-360. , MayAneja, I.A., Dynamic interacting response of large turbine-generators supported on foundations of different flexibilities (1982) IFToMM - INTERNATIONAL CONFERENCE, pp. 129-138. , Rome -Italy, September, 1982Cavalca, K.L., Dedini, F.G., Experimental analysis of a tilting pad journal bearing influence in a vertical rotating system (1998) IFToMM 98, pp. 571-582. , 7-10 September, Darmstadt - AlemanhaGéradin, M., Rixen, D., (1996) Mechanical Vibration: Theory and Application to Structural Dynamics, , 2nd Edition, John Wiley & SonsCavalca, K.L., Dias, Jr.M., Dedini, F.G., Determinação das Caraterísticas Modais de Bancada para Testes de Comando de Válvulas (2001) Relatório 05/2001 - DPM/FEM/UNICAMP, , Junho(1997) Theoretical and Experimental Modal Analysis, , Maia N. M. M. Silva J. M. M. (editors), John Wiley & Sons In