Propellantless foam dispenser

Claim 1

In a propellantless foam dispenser comprising: a container having a flexible outer wall which includes a base, side wall means, and a top end that is formed with an outlet opening, said container containing a foamable liquid and having an air space with said outer wall; a foam discharge nozzle associated with said outlet opening and having an inlet opening in said outlet opening of said container; said container being movable to an inverted position whereby said outlet opening is disposed below the level of said liquid in said container; a foam generator which is contained in said outlet opening and when said container is squeezed in said inverted position to generate a superatmospheric pressure in said container is adapted to generate foam and to deliver said foam to said inlet opening; said foam generator comprising a body having a shell member which is mounted in said outlet opening, and a bottom member connected to said shell member remote from said inlet opening; said foam generator containing a porous element which faces and covers said inlet opening; said bottom member being formed with liquid passage openings and with an air passage opening, and said foam dispenser also comprising a tubular air line which communicates with said air passage opening and extends therefrom close to said base; wherein the improvement comprises that said porous element comprises a sieve disc which defines a radial clearance with said shell member and is axially displaceable in said body between a first end position and a second end position in both positions of which said sieve disc is axially spaced apart from and defines a mixing chamber with said bottom member; said body further comprising a peripheral flange which extends radially inwardly from said shell member and surrounds said inlet opening and is engageable by said sieve disc to define said first end position; said body further comprising stop means which are engageable by said sieve disc to define said second end position; said sieve disc being adapted to move to said first end position and said second end position, respectively, in response to a superatmospheric pressure and to a subatmospheric pressure in said container, respectively; whereby at least a major part of the air which enters said foam discharge nozzle from the outside of said dispenser can flow through said radial clearance past said sieve disc into said mixing chamber and through said air passage opening and said air line into said container when said sieve disc is in said second position.