Solar grille

A grille pan hangs within the focal region of an angularly adjustable parabolic solar collector and is substantially horizontally disposed in all positions of the collector. An aperture in the collector and a screen mounted on the collector supporting structure are aligned along a line of sight parallel to the collector axis and aid in angularly positioning the collector to efficiently receive and reflect solar radiation.

BACKGROUND OF THE INVENTION 
This invention relates in general to solar cooking apparatus and deals more 
particularly with an improved solar grille. Such a grille is heated solely 
by solar radiation and does not consume combustible fuel to produce 
atmospheric pollutants. The fuel saving economy realized through the 
efficient utilization of solar energy is self evident. Further, such 
cooking apparatus is safe to use in locations where conventional grilles 
using combustible fuels might prove hazardous, as, for example, on a 
wooden porch or on the balcony of a high-rise apartment building. A 
further advantage resides in the relatively short heat-up time required 
before use as compared to grilles using conventional fossil fuels. 
Accordingly, it is the general aim of the present invention to provide an 
improved solar grille which offers all of the aforesaid advantages and 
which may be manufactured and marketed at relatively low cost through the 
utilization, in part, of readily available materials which require few, if 
any, manufacturing operations. 
SUMMARY OF THE INVENTION 
In accordance with the present invention an improved solar grille comprises 
a solar collector or concentrator which has a parabolic reflecting 
surface. A simple mechanical structure supports the collector for selected 
angular positioning relative to the surface of the earth to receive and 
reflect solar radiation. A grille element is supported by a pendulant 
support for gravity biasing to a substantially horizontally disposed 
position within the focal region of the collector in response to selected 
angular positioning of the collector.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Turning now to the drawing, a solar grille embodying the present invention 
and indicated generally by the reference numeral 10 comprises a collector 
indicated generally at 12 which has a parabolic reflecting surface 14. The 
collector 12 is mounted on a supporting structure, designated generally by 
the numeral 16, which supports it for movement to selected angular 
positions relative to the surface of the earth, designated by the letter 
E. A grille assembly indicated generally at 18 includes a generally 
horizontally disposed grille element 20 which is supported by a pendulant 
support to be gravity biased to a generally horizontally disposed position 
within the focal region of the collector 12 in response to movement of the 
collector to the aforementioned selected angular positions. A sighting 
device indicated generally at 21 aids in positioning the collector to 
receive and reflect solar radiation. The solar grille 10 further includes 
an apparatus indicated generally at 22 for adjusting the collector 12 to 
and releasably retaining it in selected angular position relative to the 
earth's surface E, all of which will be hereinafter further described in 
somewhat more detail. 
The collector 12 preferably comprises a thin walled parabolic shell made 
from metal or other suitable material and has a circular central opening 
23 therethrough. The focal length of the parabolic reflecting surface 14 
is preferably equal to approximately one-half the radius of the collector 
shell or bowl as measured at its outer periphery. An annular support disc 
24, which is preferably made from wood, is secured by suitable fasteners 
to the collector 12 generally adjacent its rear surface and in surrounding 
relation to the hole 23. An outrigger or loop 26 is attached to the upper 
portion of the collector 12 near the periphery of the collector shell and 
is stabilized by a cord 28 which is connected between a central portion of 
the outrigger 26 and the periphery of the collector shell. 
The grille element 20 which forms a part of the grille assembly 18 is 
suspended from the outrigger 26 by support elements 30, 30, which may, for 
example, be rigid metal straps. The illustrated grille element 20 
comprises a perforate concave metal pan which has a radius of curvature 
approximately equal to the distance from the center of the outrigger 26 to 
the focal point of the parabolic reflecting surface 14. The bottom surface 
of the grille pan 20 is preferably black for maximum heat absorption. The 
support elements 30, 30 are tied or otherwise suitably secured to the 
outrigger 26 so that the grille pan 20 hangs from the outrigger and may 
freely pivot to a generally horizontally disposed position under the 
influence of gravity. 
The cooking efficiency of the solar grille 10 is enhanced by a reflector 32 
which is mounted on the grille pan 20 and forms a part of the grille 
assembly 18. The reflector 32 is generally vertically disposed and has a 
concave reflecting surface 34 which faces in the direction of the grille 
pan 20 and the parabolic reflecting surface 14. 
Considering now the collector supporting structure 16 in further detail, 
the supporting structure includes an elongated member or rod 36, 
preferably made of wood, connected at one end to the disc 24, 
substantially as shown. A generally L-shaped support bracket 38 connected 
to the rod 36 intermediate its ends by a pivot pin 40 supports the rod for 
pivotal movement about a horizontal axis. An abutment surface 42 at the 
upper end of the support bracket cooperates with the rod 36, as it appears 
in FIG. 2, to limit its angular movement in a clockwise direction. The 
support bracket is, in turn, mounted on a base 44 for pivotal movement 
about a vertical axis relative to the base 44. 
The adjusting and retaining device 22 includes a cylindrical counterweight 
or log 46 which is tied by a cord 48 to an end portion of the rod 36 to 
overbalance the collector 12 and its loaded grille pan 20. The effective 
length of the cord 48 may be adjusted, as necessary, by winding the cord 
onto the log 46 to adjust the angular position of the collector 12 
relative to the surface of the earth E. The log 46 normally rests on a 
supporting surface, as shown in FIG. 2, and retains the collector in a 
selected angular position of adjustment. 
The sighting device 21 includes a relatively small aperture 50, formed in 
the collector shell near its outer peripheral edge, and an alignment piece 
or screen 52 mounted on the rod 36 in spaced relation to the aperture. The 
aperture 50 and screen 52 are aligned along a line of sight which is 
indicated at 54 and generally parallel to the axis of the parabolic 
surface of the collector, the latter axis being designated by the numeral 
56. 
An article to be cooked, such as a piece of meat, for example, is placed on 
the grille pan 20. The collector 12 then pivoted about the vertical axis 
of the support bracket 38 by moving the log and adjusted to an approximate 
angular position facing in the direction of the sun by winding the cord 48 
onto or paying it off the log 46. The pan 20 will remain in a 
substantially horizontally disposed position generally within the focal 
region of the collector 12. 
The sighting device 21 is used to accurately position the collector 12 to 
attain maximum cooking efficiency. When the collector 12 is positioned 
with its axis 56 properly aimed at the sun, the screen 52 will be shaded 
by the collector bowl and an image of the sun will be projected upon the 
screen through the aperture 50.