Device for the production of foam comprising: - a reservoir for the supply of foaming liquid, of variable capacity, - a liquid chamber communicating with the foaming liquid supply reservoir by an inlet opening, and with a mixing chamber by a liquid outlet opening, - a first non-return valve (21, 22) disposed at the inlet opening of the liquid chamber, - a second non-return sealing valve (411, 412; 416) disposed at the liquid outlet opening, enabling a flow leaving the liquid chamber and comprising elastic means (415, 413; 417) for holding in the closed position, - an air chamber, - compression means for compressing the air chamber and the liquid chamber in order to expel liquid and air, via the liquid outlet opening and via the air outlet opening, into the mixing chamber which comprises stirring means for producing the foam discharged towards an outlet orifice, - a return means which returns the air chamber and the liquid chamber to their uncompressed position in order to produce suction of air and liquid, the return means is a deformable elastic bell-shaped component with a smooth wall which separates the liquid chamber and the air chamber hermetically by sealing means (391, 392), characterised in that the liquid chamber corresponds to the space under the bell-shaped return means, the liquid outlet opening being formed at the top of the bell, the inlet opening of the liquid chamber being formed on a surface, at the base of the bell, separating the reservoir from at least the liquid chamber, and in that the foaming liquid supply reservoir of variable capacity comprises a movable piston which slides in sealing fashion against an inner wall of the reservoir, the movable piston being disposed opposite the inlet opening of the liquid chamber. - a reservoir for the supply of foaming liquid, of variable capacity, - a liquid chamber communicating with the foaming liquid supply reservoir by an inlet opening, and with a mixing chamber by a liquid outlet opening, - a first non-return valve (21, 22) disposed at the inlet opening of the liquid chamber, - a second non-return sealing valve (411, 412; 416) disposed at the liquid outlet opening, enabling a flow leaving the liquid chamber and comprising elastic means (415, 413; 417) for holding in the closed position, - an air chamber, - compression means for compressing the air chamber and the liquid chamber in order to expel liquid and air, via the liquid outlet opening and via the air outlet opening, into the mixing chamber which comprises stirring means for producing the foam discharged towards an outlet orifice, - a return means which returns the air chamber and the liquid chamber to their uncompressed position in order to produce suction of air and liquid, the return means is a deformable elastic bell-shaped component with a smooth wall which separates the liquid chamber and the air chamber hermetically by sealing means (391, 392), characterised in that the liquid chamber corresponds to the space under the bell-shaped return means, the liquid outlet opening being formed at the top of the bell, the inlet opening of the liquid chamber being formed on a surface, at the base of the bell, separating the reservoir from at least the liquid chamber, and in that the foaming liquid supply reservoir of variable capacity comprises a movable piston which slides in sealing fashion against an inner wall of the reservoir, the movable piston being disposed opposite the inlet opening of the liquid chamber.