Automatic self-cooling device for beverage containers

A self-cooling device for insertion in a beverage container or the like, comprising

• a refrigerant vessel means for holding a pressurized evaporative refrigerant comprising upright sidewalls terminating in upper and lower rims, a first plug hermetically sealing a lower end of said vessel, a second plug hermetically sealing the upper end of said vessel, a vent hole being formed in said sidewall near said upper end adjacent to said upper plug,
• a metering orifice for regulating the rate of escape of said refrigerant from said vessel formed axially through said upper plug,
• an automatic pressure actuated means for releasing said refrigerant comprising a plug cylinder formed radially at least partially through said second upper end plug intersecting said metering orifice, a pressure actuated piston positioned in and movable in said cylinder, a piston groove formed around said piston whereby when said container is slightly pressurized, said pressure is transmitted to said piston via said vent hole, positioning said piston at a closed position in said cylinder where said groove is beyond said orifice, but when said container is depressurized upon opening, compressed air in said cylinder ejects said piston to an open position where said groove adjoins said orifice allowing said refrigerant to expand into said beverage in said container and self-cool said device, and cooling said beverage.