Simulation of an Auto-Tuning Bicycle Suspension Fork with Quick Releasing Valves

Authors: Y. C. Mao, G. S. Chen

Abstract:

Bicycle configuration is not as large as those of motorcycles or automobiles, while it indeed composes a complicated dynamic system. People-s requirements on comfortability, controllability and safety grow higher as the research and development technologies improve. The shock absorber affects the vehicle suspension performances enormously. The absorber takes the vibration energy and releases it at a suitable time, keeping the wheel under a proper contact condition with road surface, maintaining the vehicle chassis stability. Suspension design for mountain bicycles is more difficult than that of city bikes since it encounters dynamic variations on road and loading conditions. Riders need a stiff damper as they exert to tread on the pedals when climbing, while a soft damper when they descend downhill. Various switchable shock absorbers are proposed in markets, however riders have to manually switch them among soft, hard and lock positions. This study proposes a novel design of the bicycle shock absorber, which provides automatic smooth tuning of the damping coefficient, from a predetermined lower bound to theoretically unlimited. An automatic quick releasing valve is involved in this design so that it can release the peak pressure when the suspension fork runs into a square-wave type obstacle and prevent the chassis from damage, avoiding the rider skeleton from injury. This design achieves the automatic tuning process by innovative plunger valve and fluidic passage arrangements without any electronic devices. Theoretical modelling of the damper and spring are established in this study. Design parameters of the valves and fluidic passages are determined. Relations between design parameters and shock absorber performances are discussed in this paper. The analytical results give directions to the shock absorber manufacture.

Keywords: Modelling, Simulation, Bicycle, Shock Absorber, Damping, Releasing Valve

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1330925

References:

[1] J. Y. Wong, Theory of ground vehicles, 2nd Ed., John Wiley & Sons Inc., 2001.
[2] T. D. Gillespie, Fundamentals of vehicle dynamics Society of Automotive Engineers Inc., 1992.
[3] "The Bose Suspension System - resolving the conflict between comfort and control," Bose Learning Center, 2008. Available: http://www.bose.com/controller?event= VIEW_STATIC_PAGE_EVEN T&url=/learning/project_sound/suspension_components.jsp
[4] Y. Shen, M. F. Golnaraghi and G. R. Heppler, "Load-leveling suspension system with a magnetorheological damper," Vehicle System Dynamics, Vol. 45 No. 4, 2007, pp. 297-312.
[5] A. Mehdi, "Semiactive fuzzy logic control for heavy truck primary suspensions: Is it effective?" SAE Transactions, Vol. 114 No. 2, 2005,pp. 157-165.
[6] R. Mollica and K. Youcef-Toumi, "A nonlinear dynamic model of a monotube shock absorber," Proceedings of American Control Conference, Albuquerque, NM, USA, 1997, pp. 704-708.
[7] F. D. Goncalves, Dynamic analysis of semi-active control techniques for vehicle applications, Master of Science in Mechanical Engineering, Virginia Polytechnic Institute and State University, 2001.
[8] K. J. Bathe, H. Zhang and S. Ji, "Finite element analysis of fluid flows fully coupled with structural interactions," Computers and Structures, Vol. 72, 1999, pp. 1-16.
[9] A. Beghi, M. Liberati, S. Mezzalira and S. Peron, "Grey-box modeling of a motorcycle shock absorber for virtual prototyping applications," Simulation Modelling Practice and Theory, Vol. 15 No. 8, 2007, pp.894-907.
[10] P. Yang, Y. H. Tan, J. M. Yang and N. Sun, "Measurement, simulation on dynamic characteristics of a wire gauze-fluid damping shock absorber," Mechanical Systems and Signal Processing, Vol. 20 No. 3, 2006, pp. 745-756.
[11] E. L. Wang and M. L. Hull, "A model for determining rider induced energy losses in bicycle suspension systems," Vehicle System Dynamics, Vol. 25 No. 3, 1996, pp. 223-246.
[12] V. Pracny, M. Meywerk and A. Lion, "Full vehicle simulation using thermomechanically coupled hybrid neural network shock absorber model," Vehicle System Dynamics, Vol. 46 No. 3, 2008, pp. 229-238.
[13] C. Heritier, Design of shock absorber test rig for UNSW@ADFA Formula SAE car, Initial Thesis Report, School of Aerospace Civil and Mechanical Engineering, Australian Defense Force Academy University of New South Wales, 2008.
[14] J. Titlestad, T. Fairlie-Clarke, M. Davie, A. Whittaker and S. Grant, "Experimental evaluation of mountain bike suspension systems," ACTA Polytechnica, Vol. 43 No. 5, 2003.
[15] D. H. Wang and W. H. Liao, "Semi-active suspension systems for railway vehicles based on magnetorheological fluid dampers," Proceedings of the ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, DETC2007-34776, 2007.
[16] H. E. Merritt, Hydraulic control systems, New York: John Wiley & Sons Inc., 1967.
[17] R. H. Warring, Hydraulic handbook, Surrey, England: Trade and Technical Press Ltd., 1983.
[18] E. C. Yeh, S. H. Lu, T. W. Yang and S. S. Hwang, "Dynamic analysis of a double tube shock absorber for robust design," JSME International Journal Series C., Vol. 40 No. 2, 1997, pp. 335-345.
[19] G. Lindfield and J. Penny, Numerical methods using MATLAB, Prentice Hall International, 2001.