Dispenser with disengageable screw mechanism

A product dispenser, including a body (2), a cap (11), a propellant device (3) including a base plate (4) fixed to said body by assembly, and an axial screw (5), with male helical thread (50), fixed on said base plate, a plunger (6) formed of a medium (8) and of a central nut (7), with a spiral female thread (70), engaging by rotation with said axial screw, a bottom (12) for rotating said axial screw, said medium and said body including axial guide means, by engagement of at least one axial rib (20) on the inner surface of said body with at least one axial groove on the periphery of said medium, so as to provide, in the case of a cylindrical dispenser, axial movement of said stick by rotation of said knob or of said bottom, characterised in that:

• a) engagement between the male helical thread (50) and the female thread (70) is partial, one of the two threads extending only over a predetermined angular fraction (51, 71), so as to form a partial thread,
• b) said central nut (7) and said axial screw (5) including a radial resilience means, for radial distortion under stress,
• so as to allow, in the event of forced rotation under said stress and of locking of said screw relative to said nut, a disengagement, of the male and female spirals, by overlap of the spirals and clearance of a screw thread, without destroying said engagement between screw and nut,
• c) said base plate (4) and said medium (8) of said stick include open segments so as to allow said dispenser to be filled through the bottom,
• d) said medium (8) includes radial platelets (80) fixed to said central nut (7) which has, in the sectors between said radial platelets (80), a thinned down wall (72).