1. Field of the Invention
The present invention relates generally to the field of food and beverage containers. More specifically the present invention relates to a self-cooling container apparatus containing a beverage or other food item and to methods of assembling and operating the apparatus. The terms "beverage", "food item" and "container contents" are considered equivalent for purposes of this application and used interchangeably.
For the first several preferred embodiments, the apparatus includes a container such as a can containing a beverage and having a conventional unified bottom and side container wall terminating in an upper sealing flange referred to hereinafter as a container rim. A refrigerant receptacle is provided including a receptacle cup having a cup wall having an expandable portion and having a cup sealing flange, hereinafter referred to as a cup rim, which extends laterally from the cup wall. As an alternative to the cup with an expandable wall, a secondary vessel is placed within the container to contain the beverage and to define a narrow annular refrigerant chamber between the container and vessel, providing an broad surface area for heat transfer. A conventional beverage can lid is further provided, including a lid panel with a lid opener mechanism and a lid lateral edge.
A method of apparatus assembly is provided including the steps of lowering the cup through the container rim so that the cup displaces some of the beverage in the container; resting the cup rim on top of the container rim; placing the lid on top of the cup so that the lid lateral edge rests on the cup rim; and crimping the lid lateral edge and cup rim onto the container rim. Either before or after the lid is placed onto the cup, a refrigerant chilled to a liquid state is introduced into the cup. After crimping, the refrigerant is warmed to ambient temperature, whereupon it partially evaporates and develops internal pressure against the cup wall and the lid.
A method of operation is provided in which the consumer operates the lid opener mechanism to open the lid and thereby releases vaporized refrigerant from the receptacle cup. The remaining liquid refrigerant progressively boils into a vapor state and escapes through the opener mechanism, drawing heat out of the beverage through the cup wall. Once all of the refrigerant has been released, the cup wall is opened with a cup wall opener mechanism to permit the beverage to flow into the cup, and then out of the container through the lid opener mechanism for consumption.
2. Description of the Prior Art
There have previously been self-cooling containers for food items including refrigerant receptacles with widely spaced apart, rigid receptacle walls. The receptacle is opened when cooling is desired and the refrigerant is progressively discharged from the receptacle, extracting heat from the container contents. A problem with this construction is that, as the volume of the liquified refrigerant falls during discharge, the refrigerant surface area in thermal contact with the walls of the receptacle diminishes, so that progressively colder refrigerant is in contact with a progressively smaller conductive surface area. The result is an exponentially falling refrigerant evaporation rate.
It is thus an object of the present invention to provide a self-cooling container apparatus containing a refrigerant receptacle with either expandable or narrowly spaced apart walls for a rapid and efficient transfer of heat out of the container contents.
It is another object of the present invention to provide such an apparatus in which a smaller volume of cold refrigerant is exposed to a larger heat transfer surface area such as by corrugating the refrigerant receptacle wall, to increase the evaporation rate of the liquid refrigerant.
It is still another object of the present invention to provide such an apparatus which both releases refrigerant and opens passage for the container contents with a single action by the consumer.
It is finally an object of the present invention to provide such an apparatus which is inexpensive to manufacture, safe and reliable.