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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to portable solar cookers and more
particularly to a solar cooker adapted for tracking the sun with the oven
maintained in either a tilted or level position.
2. Description of the Prior Art
Solar cookers having a housing construction with solar energy reflectors
and means for transferring the solar energy to an oven area are known and
have been described in U.S. Pat. Nos. 3,025,851; 3,106,201; 3,156,234;
3,174,476; 3,236,227; 3,236,227 and 4,077,391.
One of the shortcomings of these solar cooking constructions is that they
require tilting of the oven to provide the proper orientation with respect
to the angular attitude of the sun as it moves in its semi-circular path
from east to west. This, of course, presents a problem in cooking foods
which require a level position at all times during the cooking cycle,
e.g., pizza and pot pies.
In U.S. Pat. Nos. 3,938,497 and 4,083,357, solar cooking devices are
described which maintain the oven in a level position while tracking the
sun during the cooking cycle. However, these constructions do not appear
to be very efficient and certainly do not offer a compact, portable unit
which would be inexpensive to construct.
It is, therefore, an object of this invention to provide an efficient and
inexpensive portable solar cooker in which the oven can be maintained at a
level position at all times during the cooking cycle.
SUMMARY OF THE INVENTION
A portable solar cooker is provided with an internally insulated housing
having a front opening and associated door and an oven compartment for
slidably receiving a cooking tray through the front opening. The solar
cooker is adapted either for cooking with the oven compartment in an
angled or tilted position or with the oven compartment maintained in a
level position. Removable brackets are mounted directly on the top of the
housing and receive appropriate sun reflectors when the solar cooker is
adapted for cooking with the cooker tilted to insure maximum collection
and transfer of solar radiation into the oven compartment for cooking
purposes. When it is desired to cook in a level relation, a second set of
brackets are installed on top of the housing to replace the first set and
a pivotal frame and associated telescoping reflector strip assembly are
adjustably mounted thereon. With this assembly installed, the sun
reflectors are removably mounted on a top portion of the reflector strip
assembly frame and are angularly adjustable thereon. The sun reflectors
are positioned by adjusting the telescoping strip assembly so that the
sun's radiation is always most advantageously directed into a
heat-generating area directly above the oven compartment which can remain
level during cooking.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial view illustrating the solar cooker construction
adapted for cooking with the housing and oven compartment in a tilted
position so that the sun reflectors are positioned to most efficiently
trap the sun's radiation.
FIG. 2 is a pictorial view illustrating the solar cooker construction
adapted for cooking with the housing and oven compartment maintained in a
level position and with the telescoping reflector strip assembly installed
and moved into the most efficient position to trap the sun's radiation.
FIG. 3 is a side elevation section view taken substantially along line 3--3
of FIG. 1 illustrating how the sun reflectors are installed on the cooker
housing.
FIG. 4 is a side elevation section view taken substantially along line 4--4
of FIG. 2 illustrating how the telescoping reflector strip assembly is
installed and how the sun reflectors are, in turn, installed on the
telescoping reflector strip assembly.
FIG. 5 is a pictorial view illustrating the portable solar cooker of the
present invention collapsed and ready for storage or transporting to
another location.
FIG. 6 is a pictorial view of the telescoping reflector strip assembly
removed from the cooker.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the drawings, there is illustrated a portable solar
cooker 10 comprising a generally box-like housing 11, support legs 12,
four removably mounted side sun reflectors 13, 15, 17, 19, and four
trapezoidal corner sun reflectors 14, 16, 18 and 20. Support legs 12 are
pivotally mounted to allow cooker 10 to be tilted to a position
substantially normal to the incident solar rays when it is desired to cook
with the cooker 10 in an angled or tilted position and also allows for
legs 12 to be utilized as a handle for carrying purposes when the cooker
is not in use. Pivot/mount knob 25 allows for loosening or tightening upon
legs 12.
Housing 11 is formed by outer walls made from sheet metal, plastic or other
suitable materials. Housing 11 encloses an oven compartment 41 which is
defined by a bottom 42, a heat collector roof 43, side walls 44, 45 (not
shown) and back wall 46. The front side of oven 41 is closed by a door 47
which is designed to fit snugly over the front of oven 41 to form a
substantially airtight seal with the aid of rubber seal 47a. A cooking
tray 48 (shown in dashed lines) slidably fits into oven 41 by means of
door 47. Door 47 pivots about hinge 49 and has a small hole 50 of diameter
sufficient to receive in a sliding fit manner the shaft portion 51 of a
cooking thermometer 52 for external reading of the oven temperature. As
seen in the drawings, the spacing between outer walls 40 and oven
compartment 41 is filled with a suitable insulating material 53 as is the
inside of door 47. A pair of latches 54 and 55 (not shown) secures door 47
when closed.
Referring to FIGS. 3 and 4, a heat generating area 60 is situated directly
above oven compartment 41. As illustrated, oven compartment 41 is
surrounded by insulating material 53. The tops of each piece of insulation
are cut away to receive a sheet of glazing comprising a heat shield 61
made from a substantially clear fiberglass sheet. Heat shield 61 is
appropriately secured to the top of housing 11. Shield 61 overlies heat
generating area 60 which, in the present embodiment, provides an air space
of approximately 0.7874 inches (20 mm) in depth (dimension X) overlying
roof 43 of oven compartment 41. The top surface of roof 43 is painted
black to enhance its ability to absorb solar energy. Briefly stated, solar
energy is trapped under shield 61 and transferred therethrough into heat
generating area 60 and onto the black top surface of heat collecting roof
43 of oven compartment 41 and then is transmitted through roof 43 into
oven compartment 41.
Four removable brackets 26 are secured to the outer edges of the top of
housing 11 by screws 27 passing through holes 28 in brackets 26 and holes
29 (not shown) in the top of housing 11. Brackets 26 are substantially
L-shaped with the base leg portions having holes 28 predeterminably spaced
therein. The vertical leg portions of brackets 26 are outwardly inclined
slightly and have channels 30 made integrally therewith for receiving sun
reflector panels 13, 15, 17, 19, therein. Brackets 26, as previously
mentioned, are removably secured on the top outer edges by screws 27.
Holes 28 in the base leg portions of brackets 26, and holes 29 (not
shown), in the top of housing 11, are designed to align for receiving
screws 27. Sun reflectors 13, 15, 17 and 19 are side panel reflectors and
are slidably received in channels 30 of the vertical leg portions. Once in
channels 30, reflectors 13, 15, 17 and 19 are held snugly in place
therein. Reflectors 13, 15, 17 and 19 have cut-outs or notches 31 located
in the outer lower edges thereof. Cut-outs 31 receive in a sliding fit
manner therein trapezoidal corner light reflector panels 14, 16, 18, and
20. Reflector members 13, 14, 15, 16, 17, 18, 19 and 20 have mating snap
fits 32 located in the outer top edges thereof and which snap together to
hold reflectors 13-20 together as a unit supported by channels 30 of
brackets 26. FIG. 1 illustrates portable cooker 10 set up for use in the
manner just described where housing 11 and oven compartment 41 may be
tilted for cooking without causing any problems with the product being
cooked. Pivot/mount knob 25 is slightly loosened until housing 11 is
positioned in the desired manner at which time pivot mount/knob 25 is
retightened.
To aid in properly positioning portable solar cooker 10 so that as much as
possible of the sun's energy is captured for cooking purposes, alignment
slits 63 are cut into the lower midportions of panels 13, 15, 17, 19
perpendicular to the bottom edges of light reflector panels 13, 15, 17 and
19. As the sun changes its position, pivot/mount knob 25 is loosened
slightly so that housing 11 and oven compartment 41 may be angled or
tilted to the desired position. This proper positioning is accomplished by
initially turning cooker 10 towards the sun and slightly tightening
pivot/mount knob 25. During positioning of cooker 10, as in FIG. 1, slits
63 allow the sun's rays to pass through reflectors 13, 15, 17 and 19 where
the slits are located to form light streaks on the top side edges of
housing 11 as indicated at 64, 65. Cooker 10 is adjusted until the light
streaks are perpendicular to and aligned with the slits. Cooker 10 is then
properly positioned for gathering the sun's energy and cooking within oven
compartment 41. Slits 63 are used in a similar manner with the embodiment
of FIG. 2.
Turning now to a description of FIGS. 2, 4 and 6, solar cooker 10 in these
figures is illustrated as being adapted for cooking with housing 11 and
oven compartment 41 maintained in a level condition. In order to adapt
cooker 10 of FIGS. 1 and 3 to the cooker of FIGS. 2 and 4, brackets 26
must be removed once the sun reflectors 13 through 20 are unsnapped and
removed from brackets 26. Screws 27 are removed to take off brackets 26. A
pair of angle brackets 70 are positioned on the top edge surface of
housing 11 and are secured in place with screws 27 which pass through
holes 71 in brackets 70 and tighten into holes 29 (not shown) in the top
of housing 11. One of the brackets 70 is positioned adjacent the front or
door end of housing 11 and the other of brackets 70 is positioned to the
rear or end opposed to door 47.
A telescoping strip assembly 75 comprised of U-shaped strips of a
reflecting material 89 is now ready for installation on housing 11. A top
frame 76 is hingedly connected to housing 11 at the rear thereof by screws
77 which pass through hinge 78 and fasten into the back wall of housing
11. Hinge 78 is integrally secured on its other side to frame 76. Once
screws 77 are tightened, frame 76 is now pivotally secured to housing 11.
A pair of arms 79, 80 are pivotally secured to frame 76 at a predetermined
location and extend downward from the inside surface of frame 76. A second
set of arms 81, 82 are pivotally secured to a pair of brackets 83, 84.
Arms 81, 82 are pivotally linked to arms 79, 80 by screws 85, 86 and wing
nuts 87 and 88 (not shown). With arms 79, 81 and 80, 82 linked together
respectively by screw 86 and wing-nut 88, brackets 83 and 84 are ready for
securement to the top of housing 11 by screws 27. Once brackets 83, 84 are
secured, top frame 76 can now be raised or lowered while pivoting about
hinge 78. Once top frame 76 is in the desired position, wing-nuts 87, 88
are tightened and in effect locks the arms in a fixed position.
Telescoping reflector strips 89 are pivotally secured at one end to top
frame 76 so that they pivot about pin 90. Reflector strips 89 are formed
so that each fits over the other, see FIG. 6. Strips 89 are linked
together by any suitable means which in this case is illustrated as a pair
of cords 91, 92 integrally secured to each of the reflector strips 89.
When wing-nuts 87, 88 are loosened and top frame 76 raised, strips 89 are
spread from their overlapping position into an open relation as shown in
FIG. 2.
Four brackets 93 are integrally secured to the top edge surfaces of top
frame 76. Brackets 93 are identical in construction to brackets 26 but are
in this case integral with top frame 76. Brackets 93 have vertically
angled leg portions which are outwardly inclined slightly and have
channels 94 made integral therewith for receiving light reflector panels
13, 15, 17 and 19 therein. Once placed in channels 94, reflectors 13, 15,
17, 19 are snugly in place and trapezoidal corner sun reflectors 14, 16,
18, 20 are placed in cutouts 31 located in the outer lower edges of
reflectors 13, 15, 17 and 19. The reflector members 13 through 20 are snap
fit together. Once assembly 75 and reflectors 13 through 20 are completely
installed, then cooker 10 is ready to be properly positioned to receive
the sun's energy for cooking. In this arrangement, cooker 10 is maintained
level and telescoping reflector strips 89 are opened with the raising of
top frame 76. Frame 76 is raised until the sun's rays pass through the
slits in reflectors 13, 17 and the rays fall on the top side edges of
frame 76. Once this is completed, cooker 10 is turned until the sun's rays
also pass through the slits in reflectors 15, 19 and fall on the top side
edges of frame 76. The cooker is now ready for cooking with housing 11
maintained in a level manner. Adjustments can be made throughout the
cooking cycle to maintain the proper orientation of the reflectors with
respect to the angle of maximum solar radiation. This is accomplished by
loosening wing-nuts 87, 88 and properly aligning the sun's rays through
the slits and retightening the wing-nuts.
For purposes of storage or transporting the unit to another location,
cooker 10 is provided with a cover 21. Cover 21 is shaped to fit onto
housing 11 to cover heat shield 61 and protect it from damage. In the
first arrangement in which housing 11 could be tilted for cooking, cover
21 may be installed once reflectors 13 through 20 are removed from
brackets 26. Cover 21 will reside over brackets 26 and snap fit into
appropriate retainer means 22 as buttons 23 on the sides of cover 21 are
received by retainer means 22. In the second arrangement in which housing
11 is maintained level for cooking, cover 21 may be installed once
reflectors 13 through 20 are removed from brackets 93 and telescoping
reflector strip assembly 75 collapsed into a flat position upon the
loosening of wing-nuts 87, 88. A pair of retainer pieces 22 are integrally
secured to the sides of frame 76 and receive buttons 23 on the sides of
cover 21 and, in effect, covers telescoping reflector strip assembly 75
and heat shield 61. Once cover 21 is installed in either arrangement,
support legs 12 are moved together by loosening pivot/mount knobs 25 and
thereby forming a handle once pivot/mount knobs 25 are retightened. FIG. 5
illustrates this position. The reflector plates 13-20, once removed, may
be conveniently stored within cover 21.
The described U-shaped interior light reflecting telescoping type wall has
been found practical in application. In use, it will be seen that such
wall structure establishes a light collecting opening surrounded by the
bottom edges of the reflector plates and provides an extensible and
collapsible wall surrounding the space between such light opening and the
heat shield. Thus, the oven compartment can remain level during cooking
and the plane of the light collecting opening can be adjusted to remain
perpendicular to the light rays as the sun changes position.
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