U.S. patent application number 09/974389 was filed with the patent office on 2002-08-08 for miniature thermoelectric cooler.
Invention is credited to Chornenky, Victor I., Jaafar, Ali.
Application Number | 20020104318 09/974389 |
Document ID | / |
Family ID | 26952220 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104318 |
Kind Code |
A1 |
Jaafar, Ali ; et
al. |
August 8, 2002 |
Miniature thermoelectric cooler
Abstract
A miniature thermoelectric cooling device for storing small
amounts of thermally unstable substances, like drug vials with
insulin for diabetic patients or protein based drugs for
thrombolytic therapy, is disclosed. A solar energy collector
coupled with a rechargeable battery is provided as the energy
source. The miniature cooler is small enough to be belt-carried at
all time by a person, whose life or health depends on the drugs.
When switched to a heating mode, the thermoelectric device can
temporarily elevate the temperature of the drug to a body
temperature thus providing comfortable conditions for the
injection. A combined solar-and-battery power supply allows keeping
an article in the cooler at low temperatures around o'clock at all
times during substantially long travels in hot or tropical
conditions where even short term exposure to surrounding
temperatures can destroy the potency of the drug.
Inventors: |
Jaafar, Ali; (Eden Prairie,
MN) ; Chornenky, Victor I.; (Minnetonka, MN) |
Correspondence
Address: |
BRIGGS AND MORGAN
2200 First National Bank Building
332 Minnesota street
Saint Paul
MN
55101
US
|
Family ID: |
26952220 |
Appl. No.: |
09/974389 |
Filed: |
October 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60267106 |
Feb 8, 2001 |
|
|
|
Current U.S.
Class: |
62/3.6 ;
62/235.1; 62/236; 62/3.62 |
Current CPC
Class: |
F25D 2400/12 20130101;
A61J 1/165 20130101; F25B 27/002 20130101; F25B 2321/0251 20130101;
F25B 21/02 20130101 |
Class at
Publication: |
62/3.6 ; 62/3.62;
62/235.1; 62/236 |
International
Class: |
F25B 021/02; F25B
027/00 |
Claims
What is claimed is:
1. A miniature cooler comprising: a storage compartment made of
thermally insulating materials and having top and side walls with
said top wall openably-connected to said side wall such that said
top wall closes the compartment or allows access to the
compartment; a power supply including a photovoltaic collector
panel and a rechargeable battery, said panel being externally
attached to said compartment sidewall and electrically connected to
said rechargeable battery, said photovoltaic collector being
provided for generating to cool said compartment and to recharge
said battery; and a temperature control system comprising: a
thermoelectric unit imbedded in said top wall of the compartment,
said unit having a hot end and a bottom end, said hot end of said
unit facing upwardly and said cold end of said unit facing
downwardly from said top wall, respectively; a control unit
operationally connected to the thermoelectric unit and the power
supply, said control unit being provided for selectively turning
said thermoelectric unit on and off; and a temperature sensor
placed inside the storage compartment and operatively connected to
said control unit.
2. The miniature cooler of claim 1 wherein: the storage compartment
further additionally includes a Dewar flask, in which the articles
to be stored are placed.
3. The miniature cooler of claim 1 wherein: the volume of the
storage compartment is less than 250 cc.
4. The miniature cooler of claim 1 wherein: the power output of the
solar battery is less than 10 W.
5. The miniature cooler of claim 1 wherein said thermoelectric unit
comprises semiconductors connected electrically in series and
thermally in parallel.
6. The miniature cooler of claim 5 wherein said semiconductors are
made of bismuth telluride.
7. The miniature cooler of claim 5 wherein: the storage compartment
further additionally includes a Dewar flask, in which the articles
to be stored are placed.
8. The miniature cooler of claim 5 wherein: the volume of the
storage compartment is less than 250 cc.
9. The miniature cooler of claim 5 wherein: the power output of the
solar battery is less than 10 W.
10. The miniature cooler of claim 5 and further comprising a belt
for attachment of said cooler, said belt for wearing around the
waist of a person.
11. The miniature cooler of claim 1 and further comprising a belt
for attachment of said cooler, said belt for wearing around the
waist of a person.
Description
FIELD OF INVENTION
[0001] This invention relates to thermoelectric temperature control
devices, used for creating a zone of lowered temperatures for
storing articles with low thermal stability. The invention is most
suitable for storing small articles, mainly drug vials with protein
based drugs, primarily insulin for the diabetic patients or drugs
for out-of-hospital thrombolytic therapy.
DESCRIPTION OF THE PRIOR ART
[0002] Portable coolers that can be comfortably carried by a person
are well known. Typically, such coolers comprise a storage
compartment with thick walls, fabricated of a polystyrene foam with
closed cells and provided with a lid and a carrying handle. For a
limited time this thermally isolated compartment can maintain
constant temperature. To compensate for the heat transfer that does
occur through the walls of the compartment and to maintain a low
temperature in the compartment for longer period of time, a
thermoelectric, or Peltier, device is often employed.
[0003] According to the Peltier effect, an electric current passing
through the junction of two dissimilar materials causes generation
or absorption of heat, with the direction of heat flow depending
upon the direction of the current. The rate of the thermal
effect--the heat flow--is proportional to the magnitude of the
current. By positioning a multitude of such junctions thermally
parallel and electrically in series in a small space a significant
thermal effect can be achieved. Such devices are now commercially
available with junctions of n-type and p-type semiconductors
materials. These devices are operable in a range of DC voltages. A
fan, generally associated with the device, is used to circulate air
from the p-n junctions to the region where the thermal effect is
desirable.
[0004] About 16 million of people in the United States and 120
million people worldwide suffer from diabetes. Life and health of a
significant number of these patients often depends on daily
injections of insulin. Insulin, like many other protein based
drugs, has relatively low thermal stability. The storage of insulin
solution in vials requires low temperature environment, preferably
a temperature range 4-10 degrees Centigrade. At room temperature an
insulin solution can preserve its potency only for a limited period
of time, at most several weeks. When traveling, people with
diabetes experience additional inconvenience associated with lack
of low temperature environment required for the storage of insulin.
In a tropical climate or during a hot day at the beach even short
term exposure of the insulin to elevated temperatures can destroy
its potency and thus jeopardize the health or even life of a
diabetes patient. This is especially true for long vacations during
summer time in the United States or in other countries with hot
climate.
[0005] In U.S. Pat. No. 5,379,594 a portable, hand-held, solar
energy thermoelectric device for the use, storage and
transportation of substances requiring a temperature controlled
environment in a wide ambient temperature range is disclosed. The
storage chest described in the patent has at least 1 cubic foot of
usable volume and consumes about 70 watts of electric power from
generated by a solar energy collector. This thermoelectric chest is
too large to meet the requirements for a drug storing cooler
capable of being carried at all the time with a person.
[0006] In U.S. Pat. No. 4,981,019 a portable food container is
disclosed. It is cooled by a solar powered refrigeration unit and
includes a thermoelectric power unit and heat pipes so that the
container will be cooled even when there is no solar radiation and
will have an even temperature distribution. The intended use of the
cooler is a picnic food container. Once again, this device is too
large to be conveniently carried by a person at all times.
[0007] It is desirable to develop a miniature temperature
controlled device, which could be carried with a person at all time
and would guarantee stability of the insulin or other drug during
several months in hot or tropical climate.
[0008] It is an object of the present invention to provide a
miniature thermoelectric cooler that can be carried with a person
at all time.
[0009] It is another object of the present invention to provide a
cooler with a power supply comprising a solar energy collector
coupled with an electrical rechargeable battery, with an overall
capacity of large enough to power the cooler around the clock
during days and nights at all times.
SUMMARY OF THE INVENTION
[0010] The present invention is a miniature belt-carried cooler
intended for long term storage of small articles, particularly
drugs, at lowered temperatures. The present invention comprises a
thermally isolated storage compartment, a solar power collector
coupled with a rechargeable electric battery and a thermoelectric
unit. The solar energy collector and rechargeable batteries are
secured to the side walls of the storage compartment and serve as a
power supply for the thermoelectric system providing control of the
temperature inside the storage compartment. The thermoelectric
system includes a block of Peltier elements, a programmable control
unit, mounted on the top wall of the storage compartment, and a
temperature sensor placed inside the storage compartment.
[0011] The storage compartment is made of thermally insulating
materials, with its top wall openably connected to the side wall of
the compartment. The storage compartment may include a Dewar flask
for additional thermal insulation of the stored article.
[0012] A solar energy collector generates enough power to cool the
compartment and to recharge the battery at the same time. The
capacitance of the fully charged electric battery is sufficient to
power the thermoelectric system during nights, when solar energy is
not available.
[0013] The hot end of the Peltier unit extends up from the top wall
of the storage compartment, whereas the cold end of the unit
extends down from the top wall inside the storage compartment. The
hot end of the Peltier unit is provided with a radiator, which
serves as a heat sink, dissipating heat to the surrounding air.
[0014] A belt for wearing a cooler in accord with the present
invention at a person's waist may be provided.
[0015] The foregoing objects of the invention will become apparent
to those skilled in the art when the following detailed description
of the invention is read in conjunction with the accompanying
drawings and claims. Throughout the drawings, like numerals refer
to similar or identical parts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of a miniature thermoelectric
cooler in accord with the present invention.
[0017] FIG. 2 is a schematic view of the miniature thermoelectric
cooler shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The present invention comprising a miniature thermoelectric
cooler 10 will be described with reference to FIGS. 1 and 2. Cooler
10 comprises a thermally insulated compartment 12 adapted for
storage of the drug vials or other small articles 14 at lowered
temperatures. The compartment 12 has a bottom wall 16 and side
walls 18 made of a thermally insulating material, such as a closed
cell foam material. A top wall or lid 20 of the compartment is
openably-connected to its side wall 18. Compartment 12 may include
a Dewar or double wall flask 22, made of glass or stainless
steel.
[0019] A thermoelectric unit 24 is shown attached to the lid 20. A
heat sink 26 is attached to the hot or upper end 28 of the
thermoelectric unit 24. Heat sink or radiator 26 protrudes through
an appropriately configured opening 30 in the top wall 12 so as to
be exposed to the ambient environment. That is, the heat 26 sink
serves for cooling of the hot end 28 of the thermoelectric device
by the surrounding air.
[0020] Preferably, the cooler 10 is powered by a renewable energy
resource. By way of example, cooler 10 may include a photovoltaic
collector panel 32 for collecting the solar energy during day time
hours. Panel 32 will provide electric power to charge one or more
electric batteries 34, which provide power to the thermoelectric
cooling system during nights, when the solar energy is unavailable.
Advantageously, the power output of the solar battery 34 may be
less than 10 watts. A programmable control unit 36 may be mounted
on the top wall 20 to provide control of the temperature inside the
storage compartment 12. The temperature inside the storage
compartment may be measured by a temperature sensor 38. The whole
cooler assembly is secured on a waist belt 40, which allows to
comfortably carry the cooler at all time.
[0021] FIG. 2 schematically shows a cross section and electric
circuits of a cooler in accord with the present invention. The
miniature cooler may comprises a compartment 12 having a volume of
100-250 cubic centimeters with the top wall 20 and side walls 18
fabricated of a closed cell polymeric foam, such as polystyrene.
Located interior to the side walls 18 is the Dewar flask 22. The
flask 22 includes a space 42 between the two walls 44 and 46
thereof, which is evacuated to a high level of vacuum. The vacuum
between the walls 44 and 46 reduces the transfer of heat to or from
the cooler 10. Dewar flasks provide excellent thermal insulation
from environment and often are used for storing liquid gases.
[0022] As noted, a thermoelectric unit 24 is secured in the middle
of the top wall 12 with its cold end 48 facing the interior of the
Dewar flask 22 and the hot end 28 attached to the heat sink 26. The
thermoelectric unit 24 consists of two or more elements 50 of
semiconductor material (such as bismuth telluride) that are
connected electrically in series and thermally in parallel. These
thermoelectric elements 50 and their electrical interconnects are
mounted between two ceramic substrates 52 and 54 at their top and
bottom ends 28 and 48 respectively. The substrates 52 and 54 serve
to hold the overall structure together mechanically and to insulate
the individual elements 50 electrically from one another and from
external mounting surfaces. Preferably, the various components of
the cooling elements 50 are integrated in a cylindrical plug (not
shown for purposes of clarity) that fills the neck of the Dewar
flask 22. During operation of the cooler the semiconductor elements
50 actually are moving the heat from the colder end of the
compartment 12 to the upper hotter end 28 and heat sink 26. The
thermoelectric unit 24 is powered by a low voltage direct current
from rechargeable batteries 32 located outside the storage
compartment. A thermocouple 38 or other temperature sensor, placed
inside the storage compartment, measures the temperature to which
stored articles 14 are exposed.
[0023] A signal from the thermocouple 38 comes to the controller 36
and is used for stabilization of the temperature inside the storage
compartment at a preprogrammed level. The controller 36 turns on
and off the thermoelectric unit 24 depending on the temperature
inside the compartment. During the "off" state, the heat exchange
between the inside volume of the container and the environment
outside is minimal. In part this is due the fact that the thermal
convection inside the container 12 is very low, because the
articles 14 at the bottom of the container 12 are colder than the
ceramic substrate 54 above them. When the thermoelectric unit 24 is
on, the plate 54 becomes colder then the bottom of the compartment
and convection heat flow starts pumping heat from the bottom to the
flask to the cold end 48 of the thermoelectric unit 24. The overall
device thus is very efficient in keeping the internal part of the
Dewar flask cold, with very low energy being spent. The operational
state of the cooler is vertical with the heat sink and the hot end
of the thermoelectric unit positioned above the storage
compartment.
[0024] The present invention having thus been described, other
modifications, alterations, or substitutions may now suggest
themselves to those skilled in the art, all of which are within the
spirit and scope of the present invention. For example a miniature
cooler in accord with the present invention may include a universal
electrical adapter which allows the operator to use power from
electric current sources of other direct current voltages or 120
and 220 volts alternating current. In addition, the present
invention could further include a heating mode of operation of the
thermoelectric unit 24 during which the temperature of the insulin
or another drug can be elevated to the body level thus making
injections more comfortable for the patient. It is therefore
intended that the present invention be limited only by the scope of
the attached claims below.
* * * * *