Solar powered portable food container

A portable food container 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.

TECHNICAL FIELD OF THE INVENTION 
The present invention relates to the general art of containers, and to the 
particular field of food containers. 
BACKGROUND OF THE INVENTION 
Many people are finding it desirable to carry food with them as they 
travel. This situation has long existed in connection with picnics, 
lunches and the like, and has engendered a plethora of designs for picnic 
baskets, lunch boxes and the like. However, as more and more people 
travel, there is a need for food containers that can be used on trips and 
while traveling. The just-mentioned picnic baskets and lunch boxes while 
satisfactory for some uses, have drawbacks which inhibit their use in 
conjunction with travel, expecially long transit times. 
Principal among such drawbacks is the limited ability of such food 
containers to keep food cold during long trips. While such containers are 
generally insulated and can include places for ice packs or the like, such 
measures are of limited effectiveness, expecially if the food must be 
stored for several days or even weeks. 
Therefore, the art has included designs for portable refrigeration units. 
While such units are more effective than the above-described picnic 
baskets or lunch boxes, these units also have several drawbacks. For 
example, these units often are of limited effectiveness under certain 
conditions. Another problem is the possibility of having a rather severe 
thermal gradient established within the container whereby one section of 
the container is quite cold while another section is considerably warmer. 
Proper food storage requires, not only cold conditions, but uniform 
temperature in the container. 
Accordingly, there is a need for a food storage container which can 
maintain a proper environment for storing food for great lengths of time, 
and under varied conditions, and which provides a uniform temperature for 
the environment within the container. 
OBJECTS OF THE INVENTION 
It is a main object of the present invention to provide a food storage 
container which can maintain a proper environment for storing food for 
great lengths of time. 
It is another object of the present invention to provide a food storage 
container which can maintain a proper environment for storing food for 
great lengths of time, and under varied conditions. 
It is another object of the present invention to provide a food storage 
container which can maintain a proper environment for storing food for 
great lengths of time, and under varied conditions and which provides a 
uniform temperature for the environment within the container. 
SUMMARY OF THE INVENTION 
These, and other, objects are achieved by a food storage container which 
includes a refrigeration unit that is controlled by solar energy and which 
utilizes solar energy to power such refrigeration unit and which also 
contains heat pipes which distribute heat in the food storage container to 
establish a uniform temperature within that container. The refrigeration 
unit includes a pump for assisting circulation of fluid in the event the 
solar energy unit is not functioning at full speed, and that pump is 
connected to a thermoelectric power generation unit. The power generation 
unit utilizes the solar energy unit to charge a storage battery which 
operates the refrigeration unit when solar energy is not readily 
available, such as at night or if the container is stored in a dark 
enclosure for great lengths of time, such as on a train trip, or the like. 
The container also includes a fan and a thermostat for further ensuring a 
uniform temperature in the container. 
In this manner, the food storage container of the present invention can be 
kept uniformly cold for great lengths of time and under varied conditions, 
including storage in a hot, dark place, such as a baggage car or baggage 
compartment or the like.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
Shown in FIGS. 1 and 2 is a food storage container 10 embodying the present 
invention. The container 10 includes a cooling or refrigeration unit 12 
that is solar powered and a heat distribution unit 14 that ensures an even 
temperature within the container. A power unit 16 is coupled to a solar 
energy collector 18 and powers the refrigeration unit when solar energy is 
not readily available. The container 10 is thus amenable for storing food 
at a low temperature for long periods of time. 
The container 10 includes a case unit 20 which includes an open-topped 
food-containing portion 22 which is formed by a bottom outside wall 24 
having a front outside wall 26, a rear outside wall 28 and end outside 
walls 30 and 32 extending upwardly therefrom to define a receptacle 34 
having an open top 36 through which access to food stored in the container 
may be had. An interior wall 38 is connected to the front and rear outside 
walls and to the bottom wall and is spaced from the end wall 30 to define 
a compartment 40 within the case unit and adjacent to the receptacle 34. 
The container also includes a top portion 42 that has side walls 44 and 46, 
end walls 48 and 50 and a handle 52 attached to the end walls. A carrying 
handle 53 can also be attached to the case unit as shown in FIG. 2. The 
unit can include a release button that is accessible by a thumb while 
gripping the handle 52. The handles can also include padding if desired. A 
pivot means, such as pivot pin 54 in FIG. 1 or piano hinge 56 in FIG. 2 
connects the top portion to the food-containing portion. This pivot means 
permits that top to move between the FIG. 1 closed configuration in which 
the top covers the open top of the food-containing portion to the open 
configuration shown in FIG. 2 in which the food-containing portion is 
uncovered for access thereto. 
The cooling unit 12 of the container is solar powered, but can also be 
powered by a storage battery as a backup power source in the event solar 
energy is not readily available. The cooling unit 12 is shown in FIG. 3, 
and includes a solar energy collector 60 which includes an upper surface 
62 which is exposed to solar radiation, and a bottom surface 64. A space 
66 is provided within the collector and a supporting layer 68 ensures that 
material 70 is held in place against the upper surface 62. 
A conduit 72 fluidically connects the bottom surface 64 to an evaporator 74 
via a duct 76 which is fluidically connected to a condenser 78 located 
inside the receptacle 34 on the rear wall thereof. It is noted that the 
conduit 72 has an accordion folded section 80 defined therein to allow the 
top to open and close. The condenser 78 is fluidically connected to the 
conduit 72 by a duct 82 and a trap 84. The duct 82 also has a foldable 
section 86 defined therein. Refrigerant R, such as freon or the like can 
be used in the system. 
A full dicsussion of the operation of the cooling unit shown in FIGS. 2 and 
3 is contained in U.S. Pat. No. 4,697,433, and the disclosure of that 
patent is incorporated herein by reference. As above mentioned, the 
container 10 is adapted to operated in the absence of solar energy, and 
thus the cooling unit includes a pump 90 fluidically connected to the duct 
82 to force fluid through the system, and a electric heater unit 92 
connected to the solar material 70 to heat such material in the absence of 
solar radiation and thus operate the cooling circuit. The pump and the 
heater are powered by the power source unit 16 that is controlled by a 
thermostat 96 located in the receptacle 34 and senses when the temperature 
in that receptacle is lower than a preset value and turns on the power 
source 16 and the pump 90. Line conductors, such as conductor 98, 
electrically connect the just-mentioned elements together. 
The power source unit 16 is a thermoelectric unit and is best shown in 
FIGS. 4, 5 and 6. FIG. 4 shows the basic power unit which has a heat 
absorbing reservoir 100 situated in the solar power unit and a heat 
rejecting reservoir 102 in heat transferring contact with the condenser 78 
to be at a lower temperature than the reservoir 100. The reservoirs are 
connected together by semiconducting materials A and B so that current i 
flows because of the Seebeck effect. A storage battery 104 is connected to 
the material B and is charged as current flows in the direction indicated 
in FIG. 4, that is during exposure of the container to solar radiation. 
However, if the current is reversed, the device will discharge heat at the 
reservoir 100 and absorb heat at the reservoir 102 and the unit becomes a 
refrigerator as well as a source of power for the pump and the heater as 
well as the other elements of the container 10. The battery is used to 
reverse the current flow, and is operated by a switch 108 connected to the 
thermostat 96. The switch 108 is operated by the thermostat upon such 
thermostat sensing a preset temperature in the container. A full 
discussion of the basic thermoelectric unit is contained in textbooks such 
as "Energy Conversion" by Sheldon S. L. Chang, published by Prentice-Hall 
in 1963, and the disclosure of chapter three (pages 65-106) is 
incorporated herein by reference. In this incorporated material, various 
materials are discussed as being suitable for use on such a 
thermolelectric power unit, and reference is made thereto for such 
discussion. The battery can be a re-chargeable battery such as a 
Niclel-Cadmium battery located in the bottom of the container to be easily 
acessible for replacement, if so desired. 
The power unit used in the container 10 can be either a single-stage 
device, such as shown in FIG. 5, or a cascaded device with four stages 
such as shown in FIG. 6. Each of the stages of the FIG. 6 device produces 
power P which can be used to drive the pump, the heater the thermostat or 
a fan 110 mounted in the unit to ensure that there is a uniform 
temperature in the receptacle by inducing turbulence into that receptacle. 
One of the generators shown in FIG. 6 represents the battery 104. 
To further ensure an even temperature distribution in the receptacle 34 and 
in adeal temperature of about 35.degree. F. for example, the device 10 
further includes a plurality of heat pipes, such as heat pipe 112 mounted 
in the wall of the container to have a heat absorbing end 114 located 
adjacent to the forward wall 26 and a heat rejecting end 116 located 
adjacent to the condenser 78 to reject heat to that condenser. The heat 
pipes also include hollow cylindrical bodies 118 and absorbs heat at end 
114 and releases heat at the end 116 through condensation of vapor. The 
heat pipe will operate in a specific temperature range and will thus tend 
to keep the temperature in the receptacle uniform. 
An alternative form of the container is shown in FIG. 7 as a drink 
container 10'. The container 10' includes a solar collector unit 18' and 
has a cylindrical wall 130 slidably and pivotally connected to a top 132 
by a connection 134. The connection 134 includes a leg 136 having a slot 
138 defined therein and through which a pin 140 fits. 
It is understood that while certain forms of the present invention have 
been illustrated and described herein, it is not to be limited to the 
specific forms or arrangements of parts described and shown.