Method and apparatus for forming a clear frozen drinking vessel

The present invention relates to a method and apparatus for forming a drinking vessel which is substantially free of contaminants. A consumable liquid is added to a container. The liquid is stirred while freezing the liquid allowing contaminants to flow towards the center of the liquid. A layer of ice forms on the inside of the container which is substantially free of contaminants to form the drinking vessel. In one embodiment, gas is bubbled into the liquid for stirring the liquid. Alternatively, a propeller can be used to agitate the liquid.

1. Field of the Invention 
The present invention relates to a clear drinking vessel and a method and 
apparatus for forming the drinking vessel in which the vessel is 
substantially free of contaminants. 
2. Background of the Invention 
Drinking vessels formed of ice for chilling and holding liquids are known. 
U.S. Pat. No. 1,123,537 describes an apparatus for the manufacture of a 
drinking vessel made of ice. The apparatus includes a conical mold and a 
conical core. The conical core has greater conicity than the mold. A body 
of liquid is introduced between the mold and the core and is subjected to 
refrigeration. A piston can be used to remove the formed drinking vessel 
from the mold. 
U.S. Pat. No. 4,625,518 describes a method and apparatus for forming an ice 
mug in which the ice mug includes a frozen handle secured thereto. A mold 
has a shaped interior baffle. The mold is filled with a consumable liquid. 
The liquid is frozen to form a frozen container. Thereafter, the container 
is released from the mold. A handle is embedded into the container by 
heating a portion of the sidewalls of the container, inserting the handle 
into the heated portion and refreezing the melted area. The 
above-described patents have the drawback that any contaminants in the 
liquid become part of the frozen container. The contaminants can be 
released into a liquid contained in the container when the inside of the 
container melts and the contaminants also can give the mug a non-clear 
appearance. 
U.S. Pat. No. 3,065,606 relates to a drinking cup having an outer cup of an 
insulating material and a layer of ice within the outer cup. An inner 
lining lines the inner surface of the ice to prevent melting ice from 
diluting the beverage contained in the cup and weakening the content of 
the beverage. This patent has the limitation of requiring additional 
materials for forming the ice mug which can increase costs of the 
manufacture and must be disposed of after use. 
Of possible general relevance are U.S. Pat. Nos. 4,505,121; 3,091,194 and 
2,952,133. 
SUMMARY OF THE INVENTION 
Briefly described the present invention comprises a method and apparatus 
for forming a drinking vessel in which the drinking vessel is 
substantially free of contaminants. It is known that pure water, which is 
free from impurities, will freeze before unpure water. It is also known 
that a body of water freezes from the outside edge surfaces towards the 
center of the body. Accordingly, during freezing, impurities in the water 
will move towards the warmth of the center of the body and flow away from 
the outside edge surfaces. Thus, the movement of impurities allows purer 
water to freeze at the outside edge surface of the body of water. The 
method and apparatus of the present invention provide movement of the 
water during freezing for allowing the impurities to flow towards the 
center of the body of water. 
The method includes the steps of adding a consumable liquid to a container. 
Thereafter, the liquid is stirred during freezing of the liquid for 
drawing the impurities towards the center of the liquid. A layer of ice 
forms on the inside surface of the container which is substantially free 
of contaminants and forms the drinking vessel. In one embodiment, the 
stirring step is performed by bubbling a gas into the center portion of 
the liquid. In an alternative embodiment, the stirring step is performed 
by agitating the liquid with a propeller. Alternatively, the liquid can be 
stirred by both the propeller and bubbling gas through the blades of the 
propeller. 
A drinking vessel is formed by the present invention in which side walls 
are coupled to a bottom and the side walls and bottom are optically clear 
and substantially free of contaminants. 
The present invention will be more fully described by reference to the 
following drawings.

DETAILED DESCRIPTION OF THE INVENTION 
During the course of this description like numbers will be used to identify 
like elements according to the different figures which illustrate the 
invention. 
FIGS. 1A and 1B illustrate an apparatus for forming a drinking vessel 10 in 
accordance with the teachings of the present invention. A container 12 is 
formed of bottom 13 and sidewalls 14. Water 16 is received in inside 
portion 15 of container 12. Water 16 can be from any source. For example, 
water 16 can be tap water, spring water or mineral water. 
Container 12 has a predetermined size for forming a predetermined sized 
drinking vessel. Preferably, container 12 has a cylindrical shape and is 
about 4 inches in diameter and 11 inches high for forming a conventional 
size drinking vessel. It will be appreciated that various shaped and sized 
containers can be used for forming different shapes and sizes of drinking 
vessels. Container 12 can be formed of stainless steel aluminum or food 
grade plastic. Container 12 can have a thickness of a gauge of about 1/6th 
of an inch. It will be appreciated that the container can be formed of 
other materials known in the art of food processing. 
A sufficient amount of water is added to container 12 for forming the 
predetermined sized drinking vessel. Preferably, container 12 is filled to 
about 3/4 to about 7/8 full with water 16. 
Container top 18 is placed on top of container 12. Gas inlet tube 20 is 
received in aperture 24 of container top 18. Container top 18 holds gas 
inlet tube 20 in place within container 12. Gas inlet tube 20 has a 
predetermined length L.sub.1 for extending the tube a predetermined depth 
into water 16. Gas inlet tube 20 preferably extends 3/4 of the length of 
container 12 into water 16 and is about 2 to about 3 1/4 inches from 
bottom 13 of container 12. Gas source tube 22 is coupled to gas inlet tube 
20 and gas source 31 for providing gaseous bubbles 21 to water 12. 
Preferably, gaseous bubbles 21 are formed of air. Gas source 31 provides 
pressurized gas. Gas inlet tube 20 is preferably solid and can be formed 
of a plastic or a metal material. Gas source tube 22 can be formed of a 
flexible or solid tube. Gas flows from gas source 31 through gas source 
tube 22 and gas inlet tube 20 into water 16. Vents 26 are formed in 
container top 18 for allowing air generated in container 12 to escape. 
The flow of gas into water 16 constantly agitates water 16 for allowing 
impurities in water 16 to flow towards the center portion 17 of container 
12. Water 16 in center portion 17 of container 12 is typically warmer than 
water at edge portion 19 of a container 12 and impurities flow towards the 
warmer water. Water which freezes at edge portion 19 is substantially free 
of contaminants and forms optically clear ice. Examples of impurities 
which can be removed are minerals, sodium, fluoride and the like. 
Flow regulator 32 can be attached to end 33 of gas inlet tube 20, as shown 
in FIGS. 2 and 3. Holes 36 are formed in the outside surface 34 of flow 
regulator 32. Flow regulator 32 provides an even flow of bubbles 21 from 
gas inlet tube 20 to water 16. 
FIG. 4A is a perspective view of apparatus 10 during freezing of water 16 
within container 12. Container 12 is placed within a conventional freezing 
unit 60. The freezing environment is below 32.degree. F. for freezing 
water 16. Preferably, freezing unit 60 is at a temperature between about 
(-)8.degree. F. to about 5.degree. F. During freezing, a layer of ice 54 
forms along inside surface 53 of container 12 as shown in FIG. 4B. Upon 
continued freezing, the layer of ice 54 increases in thickness towards 
center portion 15 of container 12. The volume of water 16 within center 
portion 15 decreases as layer of ice 54 is formed. The freezing process is 
stopped after layer of ice 54 reaches a predetermined thickness. 
Preferably, container top 18 has an insulated rim 58 for preventing 
container top 18 from freezing to the top 57 of formed drinking vessel 56. 
The amount of time container 12 is placed in freezing unit 60 is dependent 
on the temperature of freezing unit 60 and the desired thickness of layer 
of ice 54 of drinking vessel 56. The colder the atmosphere in the freezing 
unit 60 the faster the formation of drinking vessel 56. In a colder 
environment, preferably additional bubbles are used in order to keep 
agitating water 16, thereby allowing impurities 55 to flow towards center 
portion 17 of container 12. Water 16 with impurities 55 remains in the 
inside portion of formed drinking vessel 56. 
After formation of drinking vessel 56, container 12 is removed from 
freezing unit 60. Container 12 is turned upside down for removing drinking 
vessel 56 from container 12, as shown in FIG. 5. Water 16 with impurities 
55 flows from drinking vessel 56. Drinking vessel 56 includes opening 58 
and cavity 59. Top 57 of drinking vessel 56 may be uneven. Conventional 
ironing, sanding or sawing processes can be used to form an even top 57 of 
drinking vessel 56. 
FIG. 6 is a perspective view of a second embodiment of the freezing 
environment in which container 12 is placed in container 70. Container 70 
is filled with freezing solution 72. Preferably, freezing solution 72 
circulates within container 70 for evenly contacting container 12. 
Freezing solution 72 is preferably non-toxic. Examples of freezing 
solutions 72 useful for practice of the present invention are a brine 
solution formed of salt water, and propylene glycol. 
Freezing solution 72 surrounds side wall 14 and bottom 13 of container 12. 
Top portion 74 of container 12 is not submerged in freezing solution 72. 
In this embodiment, container top 18 is not exposed to freezing 
temperatures and will not freeze to container 12. It will be appreciated 
that other freezing environments can be used for forming drinking vessel 
56. 
FIG. 7 is a perspective view of an alternative embodiment of apparatus 10 
including propeller system 80. Drive motor shaft 84 is positioned within 
container 12. Motor 81 rotates drive motor shaft 84. Propeller fin 82 is 
positioned at end 83 of drive motor shaft 84. Rotation of propeller fin 82 
in the direction of arrow A.sub.1 provides flow of water 16 in the 
direction of arrow A.sub.2 for forming a whirlpool 86 in container 12. The 
use of a propeller has the advantage of reducing the chances of air 
bubbles being frozen in the formed drinking vessel, thereby providing for 
improved integrity of the ice. 
An alternative embodiment of agitator propeller system 90 is shown in FIG. 
8. Holes 92 are formed on the outside surface 91 of propeller fin 82. 
Drive motor shaft 84 is powered by air which emerges as air bubbles 94 
from holes 92 into water 16. Agitator propeller system 90 provides 
agitation of water 16 by propeller fin 82 and air bubbles 94. 
The above described apparatus produces a drinking vessel which extracts at 
least about 95% of impurities from the drinking vessel for producing a 
drinking vessel which is substantially free of contaminants. The drinking 
vessel has the advantage that the removal of contaminants produces an 
optically clear drinking vessel for allowing a user to see the substance 
within the vessel. In addition, melting of the inside of the vessel during 
use of the vessel will not result in any contaminants being released into 
the consumable liquid held within the vessel. 
While the invention has been described with reference to the preferred 
embodiment, this description is not intended to be limiting. It will be 
appreciated by those of ordinary skill in the art that modifications may 
be made without departing from the spirit and scope of the invention.