Driver with an active piston, e.g. a piezoelectric piston, incorporating a couple of friction layers with static and dynamic friction coefficients greater than 0.6

摘要

A driver comprises a slide cylinder and a piston incorporating a number of sections of an active material, a control mechanism acting on the active material so that the sections are blocked with respect to the slide cylinder or lengthen it following a sequence that drives the axial displacement of the piston in the slide cylinder. The slide cylinder and the piston present at their interface at least one couple of friction layers with static and dynamic friction coefficients which, for a pressure between the cylinder and piston of less than 100 MPa, are greater than 0.6. The couple of friction layers also present some surface states such that their radius of curvature of ruggedness (R) obey the relationship: 0.005 mm = R = 1 mm. The average arithmetic wave lengths ( lambda a) and the quadratic average ( lambda q) of the ruggedness obey the relationship: 0.5 mu m = lambda a; and lambda q = 10 mu m. An Independent claim is also included for the fabrication of this driver