U.S. patent number 3,922,879 [Application Number 05/468,253] was granted by the patent office on 1975-12-02 for portable refrigerated work holder.
This patent grant is currently assigned to Silverado Industries, Inc.. Invention is credited to George R. Arnold.
United States Patent |
3,922,879 |
Arnold |
December 2, 1975 |
Portable refrigerated work holder
Abstract
A refrigerated work holding system wherein refrigeration is
supplied by a cooled substance within a closed container
immediately below a work surface. The container is nested within an
insulated tub, which maintains thermal insulation for the cooled
container.
Inventors: |
Arnold; George R. (Napa,
CA) |
Assignee: |
Silverado Industries, Inc.
(Napa, CA)
|
Family
ID: |
23859060 |
Appl.
No.: |
05/468,253 |
Filed: |
May 9, 1974 |
Current U.S.
Class: |
62/458; 62/257;
62/437; 62/529; 62/430; 62/457.2; 433/77 |
Current CPC
Class: |
F25D
3/00 (20130101); F25D 2331/809 (20130101); F25D
2303/0845 (20130101); F25D 2331/812 (20130101); F25D
2303/0831 (20130101) |
Current International
Class: |
F25D
3/00 (20060101); F25D 013/00 () |
Field of
Search: |
;62/530,457,430 ;32/39
;62/257,458,529,437 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wye; William J.
Attorney, Agent or Firm: Schneck, Jr.; Thomas
Claims
What is claimed is:
1. A refrigerated work holder comprising,
an insulated tub,
a closed container nestable within said tub, said container having
an upper surface which closes said tub and further having a
refrigerant substance therein which substantially fills said
container, said refrigerant substance having a heat of fusion at
least as great as that of ice, said upper surface having an area
greater than the lateral cross-section of said container.
2. The apparatus of claim 1 wherein said upper surface has an
upwardly extending lip defined about the periphery thereof.
3. The apparatus of claim 1 further defined by an insulative planar
member and means for registering said insulative planar member in
planar contact with said upper surface.
4. The apparatus of claim 1 further defined by a heat conductive
planar member and means for registering said heat conductive planar
member in planar contact with said upper surface.
5. The apparatus of claim 1 wherein said insulated tub has a flat
upper rim upon which the upper surface of said container is seated,
said rim having first and second opposed depressions facing said
container for grasping said container.
6. The apparatus of claim 1 wherein said tub has an elongated
depression therein adapted to hold tools.
7. A refrigerated work holder comprising,
a closed container having a volumetric shape which may occupy the
volume of a tub, said container having an upper work surface,
a refrigerant substance having a heat of fusion at least as great
as that of ice, said refrigerant substance substantially filling
said closed container, and
a planar member disposed in contact with said work surface and
means for aligning said planar member with said work surface.
8. The apparatus of claim 7 wherein said planar member is
insulative.
9. The apparatus of claim 7 wherein said planar member is heat
conductive.
Description
BACKGROUND OF THE INVENTION
1. Field
The invention relates to refrigeration apparatus and more
particularly to a portable apparatus for maintaining a working
surface at a refrigerated temperature.
2. Prior Art
In the practice of dentistry, there are many materials which are
mixed by dentists immediately prior to use. Many of these materials
lose their desirable properties upon exposure to elevated
temperatures. For example, certain adhesives and tooth filling
materials begin to harden upon exposure to air and such hardening
may only be reduced by limiting the exposure to air and by lowering
the temperature to slow the hardening reaction.
Apart from dentistry, catalytic adhesives have been developed which
are mixed immediately before using. Once mixing has occurred,
certain of these adhesives tend to immediately harden or set. Once
this process occurs, the adhesives lose some of their desirable
properties. This degradation can be retarded by providing
refrigeration for the mixed adhesive.
It is therefore an object of the invention to develop a compact
apparatus for refrigerating a work surface for materials which
would deteriorate upon exposure to environmental factors at ambient
temperatures.
SUMMARY OF THE INVENTION
The above object is achieved by providing a work surface in
immediate contact with a closed refrigerated container nested
within an insulated tub. Refrigeration is maintained in the closed
container by a refrigerant substance therein which substantially
fills the container. The refrigerant is preferably a frozen
material which has heat of fusion approximately equal to that of
water, or preferably greater.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the apparatus of the present
invention.
FIG. 2 is an exploded constructional view of the apparatus, with
cutaway sections of two components.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows the portable refrigerated work holder 11 of the
present invention. A work surface 13 is an insulated or heat
conductive planar member 13 which is held in place by a lip 15 of a
container beneath the planar member. An insulated tub 17 holds the
container and has a flap upper rim 19.
The detailed structure of the invention can be seen more clearly
with reference to FIG. 2. Planar member 13 may be seen to reside on
top of a first closed container 21. Note that when the closed
container 21 is nested within insulated tub 17, as in FIG. 1, the
upper surface 23 effectively closes the tub since the area of upper
surface 23 is greater than the cross-sectional area of container 21
which permits the body of container 21 to fit within tub 17 except
for the upper surface 23 which overlaps a circumferential region of
the flat upper rim 19 of tub 17. Lip 15 is connected to container
21 and extends upwardly with respect to the upper surface 23. Lip
15 provides a means for laterally positioning planar member 13
which has a thickness such that approximately half the thickness of
planar member 13 abuts the lip 15.
Container 21 has a refrigerant substance 25 enclosed therein. The
refrigerant material does not completely occupy the plenum of
container 21, but some space is left for the expected thermal
expansion of the refrigerant substance 25 upon cooling.
The refrigerant substance 25 is any material which has a relatively
large heat of fusion when frozen. Since ice has a relatively high
heat of fusion, it is a preferable refrigerant substance. It is
desired to keep the refrigerant substance from leaking and for this
purpose it is gelatinized. Various forms of gelatinized
refrigerants comprising principally water are available. A typical
substance comprises 15 parts water, 2 parts gelatinized starch
dispersed in the water and 1 part borax. Such refrigerants and the
method of preparing them are disclosed in U.S. Pat. Nos. 2,800,454
and 2,800,455.
In assembling container 21, it has been found that a preferred
method is to have the bottom side walls and lip 15 made of one
piece of plastic material and upper surface 23 of another piece.
Refrigerant is then placed in the lower portion of container 21,
leaving room for expansion, and then the upper surface 23 is
cemented into place.
Insulated bag 17 is seen to include insulation material 29
extending around the sides and bottom of tub 17. Typically, tub 17
is filled with an insulation material 29 comprising liquid
polyurathane foam insulation, or the like, which rapidly expands
and solidifies to the limit of the inside walls of container 26.
Base 37 is cemented to tub 17 shortly after the insulation is
inserted in tub 17. Tub 17 is held in a fixture, like a vise, until
the insulation has hardened. It is desirable to achieve maximum
insulation density. Therefore, the above assembly procedure is
intended to preclude formation of large air cells in the insulation
material and to achieve high density of the insulation material.
Alternate methods of forming high density insulation material 29
may also be used. For example, material 29 may be formed
externally, allowed to harden and then inserted later.
The upper surface of tub 17 is seen to include first and second
opposed depressions, 31 and 33, which face container 21 when it is
in position. The depressions are of such a size and shape that
human fingers may easily enter for grasping container 21. A third
depression 35 extends along the length of upper rim 19 for holding
tools.
In operation, container 21 is placed in a refrigerator capable of
changing the phase of the refrigerant substance 25 from its liquid
phase to a solidified phase, i.e., freezing the refrigerant
substance. It is preferred that the planar member 13 be in place
during the freezing operation. Once the refrigerant substance is
frozen, it is positioned in insulated tub 17. The relatively large
heat of fusion of the refrigerant substance will maintain planar
member 12 in a refrigerated condition for a relatively long period
of time.
Multiple closed containers, identical to container 21, may be
similarly frozen so that when the refrigerant substance in a first
container reverts to the gel phase, a second frozen container, with
a cold planar member, may be substituted.
In the practice of dentistry, it has been found that a work surface
having a width which may be grasped in the palm of the hand may be
cooled by a container having gelatinized water therein of
dimensions 14 cm. .times. 7.5 cm. .times. 3 cm. for approximately
four hours. Thus, a dentist, who places two containers 21 with
planar members 13 thereon, in the freezer compartment of a
refrigerator would have a refrigerated work surface available for
approximately eight working hours.
* * * * *