The mechanical behavior of V-belt variators during theudspeed ratio shift is different from the steady operation as a grossudradial motion of the belt is superimposed to the circumferentialudmotion. The theoretical analysis involves equilibrium equationsudsimilar to the steady case, but requires a re-formulation of theudmass conservation condition making use of the Reynoldsudtransport theorem. The mathematical model of the belt-pulleyudcoupling implies the repeated numerical solution of a stronglyudnon-linear differential system. Nevertheless, an attentiveudobservation of the numerical diagrams suggests simple anduduseful closed-form approximations for the four possibleudworking modes of any pulley, opening/closing, driver/driven,udwhose validity ranges over most practical cases. The presentudanalysis focuses on the development of such simplifiedudsolutions, succeeding in an excellent matching with theudnumerical plots, and on the comparison of the theory with someudexperimental tests on a motorcycle variator, revealing a veryudgood agreement
展开▼
