Foam dispensing pump container

A foam dispensing pump container comprising:

• a lid means;
• a double cylinder which is fastened to the container by the lid means mounted on an opening portion of said container and which comprises an air cylinder and a liquid cylinder which is smaller in diameter than said air cylinder, both arranged concentrically;
• an air piston accommodated in said air cylinder for reciprocal movements in an axial direction of said air cylinder and urged upwardly by a spring means, an air chamber formed below said air piston in said air cylinder;
• a liquid piston accommodated in said liquid cylinder for reciprocal movements in an axial direction of said liquid cylinder and urged upwardly by said spring means, said liquid piston forming, in conjunction with said air piston, an integral piston body having a hollow rod portion extending upwardly through an opening of said lid means;
• a liquid chamber formed below said liquid piston in said liquid cylinder;
• an air passage formed in a space defined by inner surfaces of an upper portion of said air piston and outer surfaces of said liquid piston;
• a liquid passage formed in said liquid piston, a mixing chamber formed above and communicating with both said air chamber and said liquid chamber through said air passage and said liquid passage respectively;
• a hollow bent nozzle member having a nose portion and a stem portion and mounted at its stem portion to an upper end of said piston body;
• a foam passage formed through said nozzle member and communicating with said mixing chamber;
• at least one porous member disposed across said foam passage;
• a first check valve disposed in a lower end portion of said liquid chamber and adapted to be opened when a negative pressure is created in said liquid chamber;
• a dip tube attached to a lower end of said liquid cylinder below said first check valve and extending to a bottom portion of said container;
• a second check valve at least partially disposed in an upper end of said liquid passage for opening an outlet of said liquid passage to said mixing chamber when said liquid chamber is pressurized;
• an air hole disposed in said air cylinder for introducing external air into a head space created in said container when said container is filled to a fill level;
• at least one suction hole provided in an upper wall of said air piston;
• and a third check valve disposed to be adapted to open and close said at least one suction hole for introducing air into said air chamber when a negative pressure is created in said air chamber,
• wherein said third check valve includes an elastic valve member, comprising a cylindrical wall portion, an outer thin annular valve portion extending outwardly from said cylindrical wall portion and an inner thin annular valve portion extending inwardly from said cylindrical wall portion, and being held at an inner surface of said upper wall of said air piston,
• said cylindrical wall portion at least partially contacting a first portion of said inner surface of said upper wall extending between said suction hole and said air passage, said outer thin annular valve portion contacting, at an outer annular rim portion, a second portion of said inner surface of said upper wall extending outwardly beyond said suction hole, and said inner thin annular valve portion contacting, at an inner annular rim portion, an annular projection which is formed below said air passage and on an outer surface of said liquid piston.