An application of a powerful tool for analysis of mechanical systems containing rolling and spinning Hertzian point contacts

摘要

This paper presents the use of a new method to analyse mechanical systems containing power-transmitting rolling and spinning Hertzian point contacts. For instance, mechanical traction-drive variators undergoing transient operating conditions. Thetechnique used combines two efficient methods: Multi-body System (MBS) computer software that handles the dynamics of these system, and numerical procedures that treat the special traction motion relationships between the bodies in contact.Several software packages for analysis of full dynamic systems are already available (e.g. ADAMS, DADS, MECHANICA). However, until now no efficient numerical procedures to solve the traction motion interactions have been available. Tormanen has recentlydeveloped new efficient numerical solutions that solve these relationships fast and with specified accuracy. By combining these solutions with an MB S-software, a powerful tool for analysis of mechanical traction drive variator is created.The contact model used was based on Coulomb's dry friction and Hertzian pressure distribution. It can also be used to display the isothermal behaviour of contacts, where a solidified oil film is present, and it is general in the sense that it can handleslip perpendicular to the rolling direction.To study the effects of transient changes of the speed ratio, this powerful tool is tested on the concept of a traction drive CVT from Torotrak Ltd. with a double-sided, full-toroidal variator. In this paper, it is demonstrated how the new tool could beused to predict theoretically the speed ratio of the mentioned CVT. In the future this will enable a theoretical refinement of control strategies for CVTs with mechanical traction drive variators.