Note: Descriptions are shown in the official language in which they were submitted.
21 70583
TITLE OF THE INVENTION:
cryogenic storage container
NAME OF INVENTOR:
Joseph Iwasenko
FIELD OF THE INVENTION
The present invention relates to a cryogenic storage
container.
R~ ROUND OF THE INVENTION
The term "cryogenics" has come to be associated with the
technology of producing temperatures below 120 degrees Kelvin.
Temperatures this low do not exist on earth under natural
conditions. In order for a cryogenic storage container to be
effective, it must be capable of contA;n;ng the cold. If the
cold is not effectively contained within the container, the
cryogenic freezing unit must operate continuously to replace
the temperature loss to atmosphere. The key to contA;ning the
cold lies in the construction of the walls of the cryogenic
storage container.
SUMMARY OF THE INVENTION
What is required is a cryogenic storage container having
walls capable of contAining the cold.
According to the present invention there is provided a
cryogenic storage container having peripheral walls defining
21 70583
a storage cavity. The storage cavity has an access opening
closed by a closure. A cryogenic freezing unit is provided
whereby the storage cavity is cooled. The characterizing
feature of the storage container is that the peripheral walls
and closure are of multi-layered construction. More
particulary, the layers include: an inner plastic liner; a
cloth layer; a first insulation layer; a plywood layer; a
second insulation layer; a reflective foil layer; and an outer
protective shell. The cloth layer is impregnated with carbon
and coated on at least one side by urethane. The plywood layer
is made of a hardwood.
BRIEF D~CPTPTION OF THE DRAnINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a top plan view, in section, of a cryogenics
storage container.
FIGURE 2 is a detailed top plan view, in section, of a
wall of the cryogenics storage container illustrated in FIGURE
1.
TT.~n ~CPTPTION OF THE rK~nK~ EMBODI~ENT
The preferred embodiment, a cryogenics storage container
generally identified by reference numeral 10, will now be
de~cribed with reference to FIGURES 1 and 2.
Referring to FIGURE 1, cryogenic storage container 10 has
peripheral walls 12 defining a storage cavity 14. Storage
cavity 14 has an access opening 16 which is closed by a closure
18. A cryogenic freezing unit 20 is provided whereby storage
cavity 14 is cooled.
3 ~1 70583
Referring to FIGURE 2, the characterizing feature of
storage container 10 is that peripheral walls 12 and closure
18 are of multi-layered construction. The layers include: an
inner plastic liner 22; a cloth layer 24; a first insulation
layer 26; a plywood layer 28; a second insulation layer 30; a
reflective foil layer 32; and an outer protective shell 34.
It is preferred that inner plastic liner 22 be of
urethane. The reason for this is that the urethane can contain
cold up to 212 degrees celsius and is light, durable and easy
to clean. Cloth layer 24 is impregnated with carbon. The
carbon impregnation is achieved through the use of a graphite
power mixed with an epoxy resin which is applied to the cloth
in the form of a spray. It is preferred that cloth layer 24
be completed by coating one side with a urethane spray
approximately 1/16 of an inch in thickness. First insulation
layer 26 can be of urethane insulation, fibreglass insulation
or other insulation with similar insulating qualities. It is
preferred that the insulation value of the insulation be
effective to -80 celsius. Plywood layer 28 is, preferably, made
from birch hardwood. Second insulation layer 30, as with first
insulation layer 26, can be made from a variety of alternative
materials. Reflective foil layer 32 has a pair of opposed
reflective surfaces 36. It is preferred that an aluminum foil
insulation be used for reflective foil layer 32. Aluminum foil
insulation has a central insulating layer sandwiched between
layers of aluminum foil. Outer protective shell 34 is
preferably made of metal or any other material that provides
protection against impact damage.
The manner in which cryogenics storage container 10
contains the cold will now be described. Urethane has been
chosen for inner plastic liner 22 because it can contain cold,
is durable and easy to clean. Carbon cloth layer 24 has a
unique property in that the carbon with which cloth layer 24
is impregnated does not absorb the cold. The carbon also
serves a secondary functions; it does not burn and, therefore,
2 1 70583
provides a measure of fire protection. The urethane spray
provides some degree of insulation, but is primarily intended
to provide a seal with inner plastic liner 22. First
insulation layer 26 and second insulation layer 30 are intended
to serve an insulating function. While various types of
insulation can be used, in order to minimize the wall thickness
of cryogenics storage container 10, a 1 inch thick layer of R40
urethane insulation is used. Positioned between first
insulation layer 26 and second insulation layer 30 is layer 28
of birch plywood. Birch plywood layer 28 need not be very
thick; 1/8 of an inch is adequate. The purpose of the layer
is to restrict passage of cold from first insulation layer 26
to second insulation layer 30. Birch, being a hardwood, is not
very porous. Unlike softwoods, such as spruce, which has
oxygen pockets; birch serves as a barrier which makes first
insulation layer 26 and second insulation layer 30 more
effective than a single layer of insulation more than twice as
thick. Reflective foil layer 32 serves an insulation function
but, more importantly, serves as a barrier to the penetration
of warmth. In cryogenics units, an atmosphere of other than
oxygen is used. The reason for this is that at the
temperatures attained an oxygen atmosphere will results in
"freezer burn". Oxygen is a heavier gas than helium or some
of the other gases that one might use. There is, therefore,
a greater danger of penetration from the exterior than
penetration from the inside out. Reflective foil layer 32
helps to prevent this penetration. Outer protective shell 34
provides impact protection to the other layers, as described
above.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embo~ nt without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
