The present device is applied to a linear driving unit which comprises: a linear electric motor (M) formed by a motor housing (C) which is electrically excited and affixed to a fixed structure (1), and by a magnetic armature (A) which is displaced in a reciprocating axial movement; and a helical resonant spring (50) having an end coupled to the fixed structure (1) and an opposite end coupled to the magnetic armature (A). The deformation control device (60) is mounted to contact a surface extension of the resonant spring (50), which is elastically and radially deformed, and to generate friction with said surface extension and/or an elastic deformation in the deformation control device (60), absorbing energy in a value sufficient to at least minimize said radial elastic deformation of the resonant spring (50).